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Natural killer (NK) cells play key roles in immune surveillance against tumors and viral infection. NK cells distinguish abnormal cells from healthy cells by cell–cell interaction with cell surface proteins and then attack target cells via multiple mechanisms. In addition, extracellular vesicles (EVs) derived from NK cells (NK-EVs), including exosomes, possess cytotoxic capacity against tumor cells, but their characteristics and regulation by cytokines remain unknown. Here, we report that EVs derived from human NK-92 cells stimulated with IL-15 + IL-21 show enhanced cytotoxic capacity against tumor cells. Major cytolytic granules, granzyme B and granzyme H, are enriched by IL-15 + IL-21 stimulation in NK-EVs; however, knockout experiments reveal those cytolytic granules are independent of enhanced cytotoxic capacity. To find out the key molecules, mass spectrometry analyses were performed with different cytokine conditions, no cytokine, IL-15, IL-21, or IL-15 + IL-21. We then found that CD226 (DNAM-1) on NK-EVs is enriched by IL-15 + IL-21 stimulation and that blocking antibodies against CD226 reduced the cytolytic activity of NK-EVs. We also show NK-EVs are taken up by target cells via macropinocytosis. Collectively, our findings elucidate the novel properties of NK-EVs and the mechanism of their incorporation into target cells.

Background: Circulating natural killer cells (NK cells) are enriched in the central nervous system in atheriosclerotic cerebral small vessel disease (aCSVD) rat models, but their resulting effects and underlying mechanism remain to be investigated.Methods: A total of 32 patients with aCSVD and 28 healthy control patients were recruited for this study. According to white matter hyperintensity (WMH) burden, which is closely related to the severity of aCSVD, 20 participants were divided into two groups: burden of 0-1 (n=10) and burden of 2-3 (n=10). All participants participated in proteomics analysis of their cytotoxic NK cells and serum, and 3 participated in proteomics analysis of their cerebrospinal fluid (CSF). In vitro BBB models and a co-culture system with primary human neurons were utilized to verify the pathogenic behaviours of cytotoxic NK cells.Results: In aCSVD patients with a high WMH burden, integrin β2 (ITGB2), cathepsin D (CTSD) and granzyme H (GZMH) were highly expressed in cytotoxic NK cells. ITGB2 interacted with intercellular adhesion molecule 1 (ICAM1) in vascular endothelial cells and promoted the adhesion of cytotoxic NK cells in vitro. Moreover, inhibition of CTSD reduced the destruction of type IV collagen (COL4A) in the extracellular matrix of the BBB and the leakiness of the BBB in vitro and in vivo, indicating that synthetic CTSD in cytotoxic NK cells participates in BBB damage. After passing through the leaky BBB, GZMH disruption on demyelinated nerve fibres was reversed by cotreatment with the inhibitor 3,4-DCIC, suggesting that cytotoxic NK cell-released GZMH is crucial for the disruption of demyelinated nerve fibres during WMH in aCSVD.Conclusions: Cytotoxic NK cells contribute to the CTSD-induced damage to the BBB and GZMH-induced disruption of demyelinated nerve fibres during WMH in aCSVD. Our work highlights the important role of cytotoxic NK cells in the disruption of nerve fibres in patients with aCSVD with a high WMH burden for the first time.

Objective To evaluates the effect of food intake on 92 oncological biomarkers to evaluate whether the timing of blood sampling could be relevant. Twenty-two healthy subjects were investigated. A total of 92 biomarkers were measured before a standardised meal as well as 30 and 120 min afterwards with the Proseek Multiplex Oncology II kit. Results The levels of 6 biomarkers decreased significantly (P Trial registration National Library of Medicine trial registration number NCT01027507 (retrospectively registered on December 8, 2009)

BackgroundAnti-programmed death (PD)-1 therapy has recently been used in recurrent or metastatic (R/M) nasopharyngeal carcinoma (NPC). The long-term survival and its biomarkers responding to anti-PD-1 treatment in patients with R/M NPC remain unclear.MethodsPatients with R/M NPC were enrolled between March 2016 and January 2018 from two phase I clinical trials. The median follow-up period was 24.7 months. Eligible patients progressed on standard chemotherapy had measurable disease by Response Evaluation Criteria in Solid Tumor V.1.1. Non-obligatory contemporaneous tumor samples were collected for whole-exome sequencing. The primary outcome was objective response rate (ORR). Duration of response (DOR), progression-free survival (PFS), and overall survival (OS) were secondary outcomes assessed in all patients.ResultsAmong 124 evaluable patients, anti-PD-1 therapy achieved an ORR of 29.8% and a durable clinical benefit rate of 60.5%. The median OS (mOS) was 17.1 months (95% CI 14.2 to 24.7), median PFS (mPFS) was 3.8 months (95% CI 3.4 to 6.0), and median DOR was 9.5 months. Significant OS benefit from treatment was observed in patients without liver metastasis (23.8 vs 13.3 months, p=0.006). Copy number deletion in genes encoding granzyme B or granzyme H (GZMB/H) was associated with poor treatment outcome (mPFS altered vs wildtype: 1.7 vs 3.6 months, p=0.03; mOS altered vs wildtype: 10.1 vs 18 months, p=0.012).ConclusionsAnti-PD-1 treatment provided promising clinical benefit in pretreated patients with R/M NPC. Copy number loss in either GZMB or GZMH genes was associated with reduced survival.

Background Pharmacological blockade of the PD-1:PD-L1 interaction with monoclonal antibodies (mAbs) has shown durable clinical responses and overall survival benefit in a variety of malignancies.1 2 Importantly, the most meaningful responses have been associated with enhancement of the antitumor effector functions of T cells as evidenced by increased peripheral T-cell proliferation, infiltration of T cells in tumors, together with increased expression of key interferon-γ (IFNγ) pathway genes, including CXCL9, CXCL10, and granzyme B in both biopsy and peripheral blood samples.3 4 To date, available therapies targeting this pathway are mAbs, but the potential advantages of a small molecule, orally administered, direct antagonist of PD-1:PD-L1 binding have led to the development of INCB086550. INCB086550 is being evaluated in a phase 1 study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics in patients with solid tumors. This preliminary report describes peripheral pharmacodynamic activity. Methods Peripheral blood was collected at baseline and at multiple time points posttreatment from 16 patients treated with INCB086550 QD (100, 200 mg) or BID (200, 400 mg). Pharmacodynamic assessments included binding of drug to PD-L1 and secretion of cytokines, IL-2 and IFN-γ with ex vivo restimulation. Measurement of downstream pharmacodynamic effects included evaluation of immune activation markers on peripheral blood cells by flow cytometry and measurement of a panel of interferon-related cytokines in plasma. Results Following INCB086550 treatment, the ex vivo stimulation of whole blood from patients showed a dose-related reduction of up to 85% in free PD-L1 on cells after 2 hours and increases as high as 3-fold of interleukin-2 secretion after 6 hours. Increases in the proliferation of circulating T cells, as measured by Ki-67, were dose-related and as high as 2.5-fold posttreatment. Plasma concentrations of CXCL9 and CXCL10 increased following INCB086550 treatment by 1.3- and 1.4-fold, respectively. A dose-related 1.2-fold increase in the plasma concentration of soluble target (PD-L1) and a 3.4-fold increase in IFN-γ was also observed posttreatment. Other proteins related to T-cell function, including but not limited to granzyme B, granzyme H, and LAG3, also increased following drug treatment. Conclusions These results indicate that oral administration of INCB086550 provides dose-related pharmacodynamic T-cell activation similar to data reported for PD-(L)1 mAbs and evidence that INCB086550 is biologically active in blocking PD-1:PD-L1 interactions, leading to T-cell proliferation and activation in patients. This trial continues to evaluate the intratumoral pharmacodynamic activity, safety, and efficacy of INCB086550. Ethics Approval The study was approved by institutional review boards or independent ethics committees of participating institutions. References Freeman GJ, Long AJ, Iwai Y, et al. Engagement of the PD-1 immunoinhibitory receptor by a novel B7 family member leads to negative regulation of lymphocyte activation. J Exp Med. 2000;192:1027–1034. Keir ME, Butte MJ, Freeman GJ, Sharpe AH. PD-1 and its ligands in tolerance and immunity. Annu Rev Immunol 2008;26:677–704. Tumeh PC, Harview CL, Yearley JH, et al. PD-1 blockade induces responses by inhibiting adaptive immune resistance. Nature 2014;515:568–571. Herbst RS, Soria JC, Kowanetz, M, et al.. Predictive correlates of response to the anti-PD-L1 antibody MPDL3280A in cancer patients. Nature. 2014;515:563–567.

NK cells lacking CD56 (CD56neg ) were first identified in chronic HIV-1 infection. However, CD56neg NK cells also exist in healthy individuals, albeit in significantly lower numbers. Here, we provide an extensive proteomic characterisation of human CD56neg peripheral blood NK cells of healthy donors and compare them to their CD56dim and CD56bright counterparts. Unbiased large-scale surface receptor profiling clustered CD56neg cells as part of the main NK cell compartment and indicated an overall CD56dim -like phenotype. Total proteome analyses of CD56neg NK cells further confirmed their similarity with CD56dim NK cells, and revealed a complete cytolytic inventory with high levels of perforin and granzyme H and M. In the present study, twelve proteins discriminated CD56neg NK cells from CD56dim NK cells with nine up-regulated and three down-regulated proteins in the CD56neg NK cell population. Those proteins were functionally related to lytic granule composition and transport, interaction with the extracellular matrix, DNA transcription or repair, and proliferation. Corroborating these results, CD56neg NK cells showed modest cytotoxicity, degranulation, and IFN-ɣ secretion as compared to CD56dim NK cells. In conclusion, CD56neg NK cells constitute functionally competent cells sharing many features of bona fide CD56dim NK cells in healthy individuals, but with some distinct characteristics.

Granzymes are serine proteases synthesized by CTL and NK cells. Five granzyme genes (GzmA, -B, -H, -K, -M) are present in humans, which are located at three different chromosomal loci. Being serine proteases, the binding pocket constitutes a catalytic triad (i.e., His59, Asp103 and Ser197). Granzymes are released into target (cancerous and virally infected) cells by a specialized process known as granule exocytosis pathway. After internalization, these proteases initiate apoptosis. Granzymes are also involved in other non-apoptotic immune associated roles like ECM remodeling, cytokine modulation, killing of pathogens through generation of phagosomes. Their intracellular activity is regulated by specialized inhibitors knows as SERPINs. However, if these proteases are secreted in excess into the extracellular environment, their regulation becomes important as otherwise they start self-damage to the tissues thereby worsening the disease conditions. Efforts are being made to identify potential inhibitors for regulation of these proteases in an extracellular environment. Physiological and synthetic inhibitors have been reported against some members however there is no known inhibitor against extracellular human GzmH. Thus, in the current study, we investigated small molecule databases for the identification of potential molecules having the ability to inhibit GzmH by combined molecular simulations, which can ultimately be used as a potential therapeutic agent.

Background Breast Cancer (BC) is the most common cancer in Iranian women, meanwhile the Iranian patients are relatively young. Granzyme H (GZMH) is a functional cytotoxic serine protease of NK cell granules, which expands the cell death-inducing repertoire of innate immune system. GZMH is constitutively and highly expressed in human NK cells, in order to possess chymotrypsin-like (chymase) enzymatic activity. The purpose of this study was to determine GZMH level, in BC and healthy women. Methods 30 breast cancer patients, and 30 control women in premenopausal status, have participated in this study. GZMH, Estrogen levels, and ER, PR have been measured in cancer and healthy women subsequently, as using ELISA, Radioimmunoassay, and Immunohistochemistry methods. Results Mean GZMH value was lower in BC than healthy women (p

Granzymes are structurally related serine proteases involved in cell death and immunity. To date four out of five human granzymes have assigned orthologs in mice; however for granzyme H, no murine ortholog has been suggested and its role in cytotoxicity remains controversial. Here, we demonstrate that, as is the case for granzyme C, human granzyme H is an inefficient cytotoxin that together with their similar pattern of GrB divergence and functional similarity strongly hint to their orthologous relationship. Besides analyzing the substrate specificity profile of granzyme H by substrate phage display, substrate cleavage susceptibility of human granzyme H and mouse granzyme C was assessed on a proteome-wide level. The extended specificity profiles of granzymes C and H (i.e. beyond cleavage positions P4-P4′) match those previously observed for granzyme B. We demonstrate conservation of these extended specificity profiles among various granzymes as granzyme B cleavage susceptibility of an otherwise granzyme H/C specific cleavage site can simply be conferred by altering the P1-residue to aspartate, the preferred P1-residue of granzyme B. Our results thus indicate a conserved, but hitherto underappreciated specificity-determining role of extended protease-substrate contacts in steering cleavage susceptibility.

Natural killer and T cell-mediated cytotoxicity is important for the elimination of viruses and transformed cells. The granule lytic pathway utilizes perforin and granzymes to induce cell death, while receptor-mediated lytic pathways rely on molecules such as FasL. Pro-apoptotic activities of Granzyme B (GrB) and Fas are well-established, and many of their cellular targets have been identified. However, humans express additional related granzymes - GrA, GrM, GrK, and GrH. Neither the cytotoxic potential of GrH, nor the mechanism by which GrH may induce target cell death is currently understood. We proposed that GrH would have pro-apoptotic activity that would be distinct from that of GrB and FasL, which could be relevant when Fas/FasL or GrB activity or death pathways were impaired. Our results, using a purified recombinant form of GrH, revealed that GrH induced cell death via a Bcl-2-sensitive mitochondrial pathway without direct processing of Bid. Additionally, neither the apoptosome nor caspase-3 was essential to the induction of GrH-mediated cell death. However, GrH did directly process DFF45, potentially leading to DNA damage. Our findings support the idea that multiple, non-redundant death pathways may be initiated by cytotoxic cells to counteract various immune evasion strategies.

Peripheral NK/T-cell lymphoma (PTCL) is a heterogeneous group of uncommon hematologic malignancies with aggressive clinical course and unfavorable prognosis. Extranodal NK/T-cell lymphoma, nasal type (NKTCL) is the most common extranodal entity worldwide, with heterogeneous geographic distribution, and it is characterized by its association with EBV, a nasal or less often extranasal presentation and aggressive behavior. Recent works using array-based technologies have provided novel insights into the pathogenesis and discovered new biomarkers with diagnostic and therapeutic implications in NKTCL. Gene expression profiling identified that most of the NKTCL are derived from activated natural killer cells with distinctively high expression of granzyme H compared to other PTCLs, which might serve as a new diagnostic biomarker. Frequent deletions and promoter methylations in PRDM1 , ATG5 , AIM1 , FOXO3 , HACE1 mapping to 6q21-q25, suggest their roles as potential tumor suppressors. The deregulation of oncogenic pathways (PDGF, JAK-STAT, AKT) provides a rationale for developing targeted therapies in the future.

The granzyme/perforin pathway is a major mechanism for cytotoxic lymphocytes to eliminate virus-infected and tumor cells. The balance between activation and inhibition of the proteolytic cascade must be tightly controlled to avoid self damage. Granzyme H (GzmH) is constitutively expressed in NK cells and induces target cell death; however, how GzmH activity is regulated remains elusive. We reported earlier the crystal structures of inactive D102N-GzmH alone and in complex with its synthetic substrate and inhibitor, as well as defined the mechanisms of substrate recognition and enzymatic activation. In this study, we identified SERPINB1 as a potent intracellular inhibitor for GzmH. Upon cleavage of the reactive center loop at Phe343, SERPINB1 forms an SDS-stable covalent complex with GzmH. SERPINB1 overexpression suppresses GzmH- or LAK cell–mediated cytotoxicity. We determined the crystal structures of active GzmH and SERPINB1 (LM-DD mutant) in the native conformation to 3.0- and 2.9-Å resolution, respectively. Molecular modeling reveals the possible conformational changes in GzmH for the suicide inhibition. Our findings provide new insights into the inhibitory mechanism of SERPINB1 against human GzmH.

The granule exocytosis pathway of cytotoxic lymphocytes plays critical roles in eradication of intracellular viruses. However, how hepatitis B virus (HBV) is cleared has not been defined. To clarify immune mechanisms underlying inhibition of the HBV replication, the relationship between granzyme H (GzmH) and HBV clearance was investigated. In this study, we found that the granule exocytosis pathway can inhibit HBV replication without induction of cytolysis of the infected cells. GzmH is essential for HBV eradication. The HBx protein (HBx), required for the replication of HBV, is cleaved at Met79 by GzmH. GzmH inhibitor can abolish GzmH- and lymphokine-activated killer cell-mediated HBx degradation and HBV clearance. An HBx-deficient HBV is resistant to GzmH- and lymphokine-activated killer cell-mediated viral clearance. Adoptive transfer of GzmH-overexpressing NK cells into HBV carrier mice facilitates in vivo HBV eradication. Importantly, low GzmH expression in cytotoxic lymphocytes of individuals is susceptible to HBV infection and hepatocellular carcinoma. These results indicate that GzmH might be detected as a potential parameter for diagnosis of HBV infection and hepatocellular carcinoma.

The granule exocytosis pathway of cytotoxic lymphocytes (Tc and NK cells) is critical for control of tumor development and viral infections. Granule-associated perforin and granzymes are key components in Tc cell-mediated function(s). On the basis of studies that showed granzymes A, B, C, K and M, to induce apoptosis in vitro, all granzymes were thought to also induce cell death in vivo. This review summarizes our present understanding of the biological processes elicited by purified granzyme A and granzyme as well as the processes induced by the more physiologically relevant cytotoxic cells secreting these proteases. The combined evidence supports the concept that the granule secretion pathway is not mono-specific but rather poly-functional including induction of pro-inflammatory cytokines, besides their widely appreciated apoptotic properties.

Tumor regressions have been observed in a small proportion of melanoma patients vaccinated with a MAGE-A3 peptide presented by HLA-A1, administered as peptide, ALVAC canarypox virus containing a MAGE-A3 minigene, or peptide-pulsed dendritic cells (DC). There was a correlation between tumor regression and the detection of anti–MAGE-3.A1 CTL responses. These responses were monoclonal and often of a very low magnitude after vaccination with peptide or ALVAC, and usually polyclonal and of a higher magnitude after DC vaccination. These results suggested that, at least in some patients, surprisingly few anti–MAGE-3.A1 T-cells could initiate a tumor regression process. To understand the role of these T cells, we carried out a functional analysis of anti–MAGE-3.A1 CTL clones derived from vaccinated patients who displayed tumor regression. The functional avidities of these CTL clones, evaluated in lysis assays, were surprisingly low, suggesting that high avidity was not part of the putative capability of these CTL to trigger tumor rejection. Most anti–MAGE-3.A1 CTL clones obtained after DC vaccination, but not after peptide or ALVAC vaccination, produced interleukin 10. Transcript profiling confirmed these results and indicated that approximately 20 genes, including CD40L, prostaglandin D2 synthase, granzyme K, and granzyme H, were highly differentially expressed between the anti–MAGE-3.A1 CTL clones derived from patients vaccinated with either peptide-ALVAC or peptide-pulsed DC. These results indicate that the modality of vaccination with a tumor-specific antigen influences the differentiation pathway of the antivaccine CD8 T-cells, which may have an effect on their capacity to trigger a tumor rejection response. [Cancer Res 2008;68(10):3931–40]

This study investigated radioresistance mechanisms in the doxorubicin-resistant acute myelogenous leukemia (AML)-2/DX100. AML-2/DX100 also showed resistance to radiation. AML-2/DX100 characterized by down-regulated catalase expression was supersensitive to exogenous hydrogen peroxide whereas they increased defense mechanisms against endogenous reactive oxygen species (ROS) as compared with AML-2/WT. In AML-2/WT, radiation increased Bax expression and its translocation to mitochondria but had little effect on translocation of Bcl-2 and consequently induced the release of cytochrome c from the mitochondria with the subsequent caspase-3 activation. On the contrary, in AML-2/DX100, radiation neither increased Bax expression nor its translocation to mitochondria while it increased Bcl-2 translocation to mitochondria. A specific p38 MAPK inhibitor SB203580 increased radioresistance in AML-2/WT but little in AML-2/DX100. It inhibited radiation-induced Bax translocation in AML-2/WT but not in AML-2/DX100, indicating that p38 MAPK is working after irradiation in AML-2/WT but not in AML-2/DX100. Electrophoretic mobility shift assay and Western blot analysis revealed that NF-kappaB in AML-2/DX100 was more activated with degradation of cytosolic IkappaBalpha than was that of AML-2/WT. cDNA microarray showed that Bfl-1/A1 and granzyme H in AML-2/DX100 were highly up-regulated (6.21-fold) and down-regulated (6.49-fold), respectively, as compared with each of AML-2/WT, which were confirmed by RT-PCR assay. Taken together, these results indicate that radioresistance mechanisms of AML-2/DX100 could be related to alterations in ROS-scavenging activity, in mitochondrial translocation of Bax and Bcl-2, and in expression of pro-apoptotic (granzyme H) and anti-apoptotic (Bfl-1/A1) genes. It has been shown that balance of p38 MAPK and NF-kappaB signals is a determinant in radiosensitivity of AML-2/WT and AML-2/DX100.

SummaryThe mechanism of target cell lysis in cytotoxic lymphocyte-mediated death is not well understood, and the role of granzymes in this process is unclear. Chemical functional probes were thus prepared for the major granzymes A and B to deconvolute their role in natural killer cell-mediated lysis of target cells. These biotinylated and substrate specificity-based diphenyl phosphonates allowed facile evaluation of selectivity through activity-based profiling in cell lysates and intact cells. Both inhibitors were found to be extremely selective in vitro and in cells. Use of these inhibitors in cell-based assays revealed granzyme A to be a minor effector and granzyme B to be a major effector of target cell lysis by natural killer cells. These studies indicate that the proapoptotic granzyme B functions also as a pronecrotic effector of target cell death.

Background: Many of the functions attributed to mast cells depend on the various pro-inflammatory mediators that are secreted upon mast cell activation. These include a panel of mast cell-specific proteases. In addition, recent studies have indicated that murine mast cells also express granzyme D, a protease previously thought to be confined to cytotoxic lymphocytes. Here, we address the human relevance of the latter findings by investigating whether human mast cells express granzyme H, the granzyme that may represent the functional counterpart to murine granzyme D. Methods: Cord blood-derived mast cells, LAD2 cells and skin mast cells in situ were evaluated for their expression of granzymes using quantitative PCR, Western blot analysis and immunostaining. Mast cells were activated by either calcium ionophore stimulation or IgE receptor cross-linking. Results: Cord blood-derived mast cells and LAD2 cells were shown to express granzyme H and B mRNA, while granzyme A, K and M expression was undetectable. Mast cell activation by either calcium ionophore or IgE receptor cross-linking caused down-regulated expression of granzyme H. In contrast, granzyme B expression was up-regulated by the same stimuli. Granzyme H expression was also confirmed at the protein level, as shown by both Western blot analysis and confocal microscopy. Further, we show that granzyme H is expressed by human skin mast cells in situ. Conclusions: The present findings implicate granzyme H as a novel protease expressed by human mast cells and support earlier findings obtained in natural killer cells suggesting that granzymes B and H are reciprocally regulated.

Mast cell proteinases are important inflammatory mediators in man and other species, but until now there has been no investigation of the nature of equine mast cell proteinases. These studies describe the purification and characterisation of two proteolytic components from equine mastocytoma tissue, detected using chromogenic substrates for trypsin and chymotrypsin. Following chromatographic purification, the trypsin-like component was found to be equine mast cell tryptase by N-terminal amino acid sequencing, showing a close similarity with human tryptase-beta (85% identity over 20 residues). It also had similar subunit molecular size (34-36kDa by SDS-PAGE) and substantially similar cleavage specificity to human tryptase-beta with the substrates tested. A 32kDa chymotrypsin-like component was also purified from mastocytoma extract, and termed equine mast cell proteinase-1 (eqMCP-1). The N-terminal amino acid sequence of eqMCP-1 was very similar to human granzyme H (95% over 19 residues). Rabbit antisera directed against tryptase and eqMCP-1 both detected equine mast cells by immunohistochemistry, and will be of use in future clinical studies of the relevance of mast cell proteinases in equine allergic disease.

Human granzyme H is a neutral serine protease that is expressed predominantly in the lymphokine-activated killer (LAK)/natural killer (NK) compartment of the immune system. The gene that encodes this granzyme is located between the granzyme B and cathepsin G genes on human chromosome 14q11.2. Although the murine orthologue of human granzyme H has not yet been identified, murine granzymes C, D, E, F, and G also lie between the murine granzyme B and cathepsin G genes on murine chromosome 14; murine granzymes C, D, and F are also highly expressed in LAK cells, but minimally in cytotoxic T lymphocytes (CTL). We therefore tested whether the 5′ flanking region of human granzyme H contains the cis-acting DNA sequences necessary to target a reporter gene to the LAK/NK compartment of transgenic mice. A 1.2-kb fragment of 5′ flanking human granzyme H sequence was linked to an SV40 large T-antigen (TAg) reporter gene and used to create six transgenic founder lines. SV40 TAg was specifically expressed in the LAK cells of these mice, but not in resting T or NK cells, in CTL, or in any other tissues. Most mice eventually developed a fatal illness characterized by massive hepatosplenomegaly and disseminated organ infiltration by large malignant lymphocytes. Cell lines derived from splenic tumors were TAg+ and NK1.1+ large granular lymphocytes and displayed variable expression of CD3, CD8, and CD16. Although these cell lines contained perforin and expressed granzymes A, B, C, D, and F, they did not exhibit direct cytotoxicity. Collectively, these results suggest that the 5′ flanking sequences of the human granzyme H gene target expression to an NK/T progenitor compartment and to activated NK (LAK) cells. Mice and humans may therefore share a regulatory “program” for the transcription of NK/LAK specific granzyme genes.

Methods In the current work, we examined NK cell (NKG2A+ CD3-) responses to SIV vaginal challenge in vaginal and cervical mucosa using IHC and ISH. Results NK cells are maintained at a low baseline level in the genital tissue of naive animals. In the first week post infection, a small number of NK cells (up to 1500 cells/cm sq) infiltrated into genital mucosa. The initial recruiting signal didn’t require viral replication as shown by equal NK influx in animals challenged with either WT or AT-2 inactivated viruses. The majority of infiltrating NK cells was Granzyme H+ and 40-60% was IFN-gamma+. However, viral inoculation also enhanced the expression of HLA-E in genital tissues, generating an inhibitory environment to NK functionality. In addition, mucosal NK cells appeared to be IL2Rbeta negative, indicating impaired IL-2 and IL15 signaling. Therefore, the initial influx of NK cells was not able to eliminate early viral infection at genital mucosa. Surprisingly, in the second week, the number of mucosal NK cells rapidly decreased, which is inversely associated with the number of infected cells in genital tissues and is consistent with an increase in the level of sera IP10 and IL18. Interestingly, at the end of the fourth week (the VL set point), the number of NK cells in genital mucosa was partially recovered, probably because of less viral replication due to CD4 depletion and a reduction of sera IP10 and IL18. Conclusion In this study, we found that densities of cervical NK cells are inversely correlated with those of infected cells in animals at Day 5-10 post infection (n=7, p=0.0187).

The apicomplexan protozoon Eimeria coecicola is an infectious agent of intestinal coccidiosis in rabbits, causing severe injuries in the appendix as the final target, but also in the liver though not being a target. Here, we investigated the effect of E. coecicola on the spleen of the rabbit Oryctolagus cuniculus with respect to structure and gene expression using 2-color Agilent whole rabbit genome oligo-microarray technology in combination with quantitative PCR. At maximal fecal output of E. coecicola oocyts on day 7 p.i., the spleen did not contain any parasites, but displayed moderate inflammatory changes evidenced as fused white pulp areas, diffuse appearance of the marginal zones, and increased number of macrophages in the red pulp, eventually resulting in an increased histological score. The infections induced 36 genes to be up-regulated and 156 genes to be down-regulated, among which were 139 genes encoding diverse regions of antibodies. The highest upregulated genes were those encoding granzyme H (10-fold), lim1 (10-fold), xanthine dehydrogenase (9-fold), whereas the downregulated genes could be majorly assigned to the immune response, as e.g. the genes encoding the macrophage cationic peptide-2 (5-fold). Quantitative PCR of genes encoding GZMH, XDH, HSD17B1, SULT3A1, SAA, BPI, MCP-2, and GST exhibited the same transcriptional level as that detected by microarray analysis. The E. coecicola -induced changes in gene expression of the spleen were totally different to those found previously in appendix and liver. Only the granzyme H gene became upregulated in all three organs. Our data indicate that the spleen, though not a final target of E. coecicola , responds to E. coecicola infections, suggesting that the spleen may be part of an orchestrated host defense against E. coecicola critically involving GZMH-expressing NK-cells.

Microarray studies have provided insight into the pathogenesis of systemic JIA and have opened new avenues for therapy. Data on the pathogenesis of the enthesitis-related arthritis (ERA) category of JIA are limited, thus we studied the expression profile of ERA patients' peripheral blood and SF mononuclear cells (PBMCs and SFMCs, respectively). PBMCs from healthy subjects were used as controls.RNA from PBMCs of ERA patients (n=17) and healthy controls (n=8) and seven ERA SFMCs were converted to labelled cRNA and hybridized to Illumina Human WG-6_v3_BeadChip chips. Expression profiles were analysed using GeneSpring software. Selected genes of interest were validated by real-time PCR.There was no significant difference in PBMC gene expression of ERA and control groups. However, there was a significant difference between expression profiles of SFMCs and PBMCs of patients with ERA, with 131 genes being overexpressed and 216 being underexpressed in SFMCs. Among genes involved with immune function, cluster of differentiation (CD)1b, CD1d, MHC class II alpha and beta chain, and soluble CD163 were overexpressed, whereas genes related to NK cell function, namely, Granzyme H, killer cell lectin-like receptor subfamily F member 1, killer cell immunoglobulin-like receptor, three domains, long cytoplasmic tail (KIR3DL3), natural killer group 7 (NKG7) and other genes like CD244, CD248 and Fas apoptotic inhibitory molecule 3 (FAIM3) were underexpressed.ERA SFMCs had a distinct gene expression profile from PBMCs and had higher expression of genes associated with antigen presentation, scavenger function, chemotaxis and proteases, whereas genes involved in NK cell function, cell adhesion and inhibitors of apoptosis were underexpressed.

Human granzyme H (GzmH) is constitutively expressed in human NK cells that have important roles in innate immune responses against tumors and viruses. GzmH is a chymotrypsin-like serine protease. Its substrate preference and its mechanism of substrate recognition are poorly understood. To provide structural insights into the substrate recognition mechanisms for GzmH, we solved the crystal structures of a D102N-GzmH mutant alone and in complex with a decapeptide substrate and an inhibitor to 2.2 Å, 2.4 Å, and 2.7 Å, respectively. The Thr189, Gly216, and Gly226 specificity triad in the S1 pocket of GzmH defines its preference for bulky, aromatic residues (Tyr and Phe) at the P1 position. Notably, we discovered that an unusual RKR motif (Arg39-Lys40-Arg41), conserved only in GzmH, helps define the S3′ and S4′ binding regions, indicating the preference for acidic residues at the P3′ and P4′ sites. Disruption of the RKR motif or the acidic P3′ and P4′ residues in the substrate abolished the proteolytic activity of GzmH. We designed a tetrapeptide chloromethylketone inhibitor, Ac-PTSY-chloromethylketone, which can selectively and efficiently block the enzymatic and cytotoxic activity of GzmH, providing a useful tool for further studies on the function of GzmH.

Human T-lymphotropic virus 1 (HTLV-1) can cause HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The objective of this study was to gain insight into the pathogenesis of HAM/TSP by focusing on the CD8(+) T-cell response. Twenty-three HTLV-1-seronegative controls (SC), 29 asymptomatic HTLV-1 carriers (AC) and 48 patients with HAM/TSP were enrolled in the study. We evaluated the production of interferon-gamma (IFN-gamma) in peripheral blood mononuclear cells stimulated with Tax overlapping peptides, the expression of genes related to the CD8(+) cytotoxic T-cell response, the frequency of CD4(+) Foxp3(+) cells and of dendritic cells, and the HTLV-1 provirus load (PVL). The frequency of cells producing IFN-gamma in response to Tax 161-233, but not to Tax 11-19, discriminated patients with HAM/TSP from AC. The increased pro-inflammatory response observed in patients with HAM/TSP was shared by AC with a high PVL, who also exhibited lower levels of granzyme H mRNA in unstimulated CD8(+) T cells than AC with a low PVL. Patients with HAM/TSP showed higher frequencies of CD4(+) Foxp3(+) cells and lower frequencies of plasmacytoid dendritic cells (pDC) than AC. Our findings are consistent with a model in which HTLV-1, along with the host genetic background, drives quantitative and qualitative changes in pDC and CD4(+) Foxp3(+) cells that lead to a predominance of inflammatory responses over lytic responses in the CD8(+) T-cell response of individuals predisposed to develop HAM/TSP.

Among the molecules proposed to be involved in cytotoxic T lymphocyte (CTL), natural killer (NK) and lymphokine activated killer (LAK) cell-mediated lysis are the granzymes, a family of serine proteases stored in the cytoplasmic granules of CTLs, NK and LAK cells. In addition to the granzymes A and B, a third member of this family has been cloned in man and designated granzyme H. We present the complete gene sequence including the 5' promoter region and demonstrate that the granzyme H sequence represents a functional gene expressed in activated T cells. Granzyme H shows the highest degree (greater than 54%) of amino acid sequence homology with granzyme B and cathepsin G and, like these genes, consists of five exons separated by introns at equivalent positions. The evolutionary history of granzyme H has been analyzed by reconstructing an evolutionary tree for granzyme sequences. We provide evidence that interlocus recombination between the ancestral genes of granzyme B and granzyme H occurred about 21 million years ago, leading to a replacement of exon 3, intron 3 and part of exon 4 in human granzyme H by human granzyme B sequences. Our results suggest that the ancestral gene of granzyme H is more closely related to cathepsin G and granzyme B than to the murine granzymes C to G. Thus, granzyme H does not represent a human counterpart of the known murine granzymes A to G. It diverged from cathepsin G before mammalian radiation and should, therefore, exist in other mammalian lineages as well.

Granzymes are key components of the cytotoxic arm of the immune response, which play critical roles in eliminating host cells infected by intracellular pathogens and transformed cells. Although the induction of cell death is likely a central process underlying the function of these enzymes, little is known about whether granzymes use additional mechanisms to exert their antipathogen activity. This study identifies La, a phosphoprotein involved in multiple roles in cellular and viral RNA metabolism, as the first nonapoptotic substrate of granzyme H (gzmH), a cytotoxic granule protease that is constitutively expressed by NK cells. Cleavage of La by gzmH occurs at Phe-364 (P(1) site) and generates a COOH-terminal truncated form of La that loses nuclear localization and decreases HCV (hepatitis C virus)-internal ribosome entry site (IRES)-mediated translational activity. The ability of gzmH to cleave host proteins involved in essential viral functions provides a novel mechanism by which granzymes can mediate direct antiviral activities.

Natural killer (NK) cells are the effectors of innate immunity to act as the first line of defense against viruses and tumors. Granzyme H (GzmH) is predicted to evolve from GzmB and constitutively expressed at a high level in human NK cells. It indicates GzmH plays a pivotal role in NK cell mediated cytolysis. However GzmH is defined as an orphan granzyme and its function has less been defined. Here we demonstrate GzmH can induce rapid apoptosis of target cells, which is dependent on caspase activation and mitochondrial damage. GzmH-induced death is characterized by phophatidylserine externalization, nuclear condensation, DNA fragmentation, caspase activation and cytochrome c release that are hallmarks of typical apoptosis. GzmH can directly cleave ICAD to unleash CAD for DNA fragmentation. Moreover, GzmH directly processes Bid to produce the active form tBid leading to cytochrome c release. Therefore, GzmH may play an essential role in caspase-dependent pathogen clearance in the innate immunity that may complement the proapoptotic function of GzmB in human NK cells.

Granzyme H (GzmH) belongs to a family of 5 human serine proteases that are expressed by cytotoxic immune effector cells. Although GzmH is most closely related to the caspase-activating granzyme B (GzmB), neither a natural substrate nor a role in immune defense reactions has been demonstrated for this orphan granzyme. In rodents, multiple related genes exist, but none of these can be regarded as functional homologs. Here we show that host cells are efficiently killed by GzmH after perforin and streptolysin O–mediated delivery into the cytosol. Dying cells show typical hallmarks of programmed cell death, such as mitochondrial depolarization, reactive oxygen species (ROS) generation, DNA degradation, and chromatin condensation. Contrary to GzmB, cell death by GzmH does not involve the activation of executioner caspases, the cleavage of Bid or inhibitor of caspase-activated DNase (ICAD), or the release of cytochrome c. The high expression levels of GzmH in naive natural killer (NK) cells and its potent killing ability strongly support the role of the protease in triggering an alternative cell-death pathway in innate immunity.

Granzymes are key components of the immune response that play important roles in eliminating host cells infected by intracellular pathogens. Several granzymes are potent inducers of cell death. However, whether granzymes use additional mechanisms to exert their antipathogen activity remains elusive. Here, we show that in adenovirus-infected cells in which granzyme B (gzmB) and downstream apoptosis pathways are inhibited, granzyme H (gzmH), an orphan granzyme without known function, directly cleaves the adenovirus DNA-binding protein (DBP), a viral component absolutely required for viral DNA replication. We directly addressed the functional consequences of the cleavage of the DBP by gzmH through the generation of a virus that encodes a gzmH-resistant DBP. This virus demonstrated that gzmH directly induces an important decay in viral DNA replication. Interestingly, gzmH also cleaves the adenovirus 100K assembly protein, a major inhibitor of gzmB, and relieves gzmB inhibition. These results provide the first evidence that granzymes can mediate antiviral activity through direct cleavage of viral substrates, and further suggest that different granzymes have synergistic functions to outflank viral defenses that block host antiviral activities.

We analyzed the expression of granzyme H in human blood leukocytes, using a novel monoclonal antibody raised against recombinant granzyme H. 33-kDa granzyme H was easily detected in unfractionated peripheral blood mononuclear cells, due to its high constitutive expression in CD3(-)CD56(+) natural killer (NK) cells, whereas granzyme B was less abundant. The NK lymphoma cell lines, YT and Lopez, also expressed high granzyme H levels. Unstimulated CD4(+) and particularly CD8(+) T cells expressed far lower levels of granzyme H than NK cells, and various agents that classically induce T cell activation, proliferation, and enhanced granzyme B expression failed to induce granzyme H expression in T cells. Also, granzyme H was not detected in NK T cells, monocytes, or neutrophils. There was a good correlation between mRNA and protein expression in cells that synthesize both granzymes B and H, suggesting that gzmH gene transcription is regulated similarly to gzmB. Overall, our data indicate that although the gzmB and gzmH genes are tightly linked, expression of the proteins is quite discordant in T and NK cells. The finding that granzyme H is frequently more abundant than granzyme B in NK cells is consistent with a role for granzyme H in complementing the pro-apoptotic function of granzyme B in human NK cells.

Although the functions of granzymes A and B have been defined, the functions of the other highly expressed granzymes (Gzms) of murine cytotoxic lymphocytes (C, D, and F) have not yet been evaluated. In this report, we describe the ability of murine GzmC (which is most closely related to human granzyme H) to cause cell death. The induction of death requires its protease activity and is characterized by the rapid externalization of phosphatidylserine, nuclear condensation and collapse, and single-stranded DNA nicking. The kinetics of these events are similar to those caused by granzyme B, and its potency (defined on a molar basis) is also equivalent. The induction of death did not involve the activation of caspases, the cleavage of BID, or the activation of the CAD nuclease. However, granzyme C did cause rapid mitochondrial swelling and depolarization in intact cells or in isolated mitochondria, and this mitochondrial damage was not prevented by cyclosporin A pretreatment. These results suggest that granzyme C rapidly induces target cell death by attacking nuclear and mitochondrial targets and that these targets are distinct from those used by granzyme B to cause classical apoptosis.

Serine proteases (granzymes) contained within the cytoplasmic granules of cytotoxic T cells and natural killer cells play a variety of roles including the induction of target cell apoptosis, breakdown of extracellular matrix proteins and induction of cytokine secretion by bystander leukocytes. Different granzymes display proteolytic specificities that mimic the activities of trypsin or chymotrypsin, or may cleave substrates at acidic ("Asp-ase") or at long unbranched amino acids such as Met ("Met-ase"). Here, we report that recombinant granzyme H has chymotrypsin-like (chymase) activity, the first report of a human granzyme with this proteolytic specificity. Recombinant 32-kDa granzyme H expressed in the baculovirus vector pBacPAK8 was secreted from Sf21 cells and recovered by Ni-affinity chromatography, using a poly-His tag encoded at the predicted carboxyl terminus of full-length granzyme H cDNA. The granzyme H efficiently cleaved Suc-Phe-Leu-Phe-SBzl (v = 185 nM/s at [S] = 0.217 mM) and also hydrolyzed Boc-Ala-Ala-X-SBzl (X = Phe, Tyr, Met, Nle, or Nva) with slower rates but had little tryptase or Asp-ase activity. Enzymatic activity was inhibited completely by 0.1 mM 3,4-dichloroisocoumarin and 84% by 1.0 mM phenylmethylsulfonyl fluoride. Fluoresceinated granzyme H was internalized in a temperature-dependent manner by Jurkat cells into endosome-like vesicles, suggesting that it can bind to cell surface receptors similar to those that bind granzyme B. This suggests a hitherto unsuspected intracellular function for granzyme H.

For the first time, human granzyme H is shown to directly induce death in tumor target cells, changing its status from orphan to killer. Cytotoxic lymphocytes are innate (natural killer [NK] cells) and adaptive (T cells) effector cells that play an important role in host defense against infection

Enzymatically active granule-associated serine protease ("granzyme") B has been purified from human NK cell lysates, using novel granzyme B-specific monoclonal antibodies. Two antibodies, designated 2C5 and 1D10, were produced following immunization of BALB/c mice with a nineteen amino acid peptide synthesized according to the sequence deduced from a granzyme B cDNA clone. Of several peptide-reactive culture supernatants that resulted from cell fusion of splenocytes with NS-1 myeloma cells, clones 2C5 (IgG2a) and 1D10 (IgG1) produced antibodies which detected a approximately 32kDa molecule in human NK cell lysates by Western blotting. This reactive species was detectable in lysates of IL-2-stimulated peripheral blood mononuclear cells, the human NK leukemia cell line YT, the rat NK leukemia cell line RNK-16, but not in the mouse cytotoxic T cell line CTLL-R8 or a variety of non-cytolytic hemopoietic tumor cell lines. The specificity of reactivity with granzyme B was demonstrated by the reaction of the monoclonal antibody with active granzyme in the lysate of COS-7 cells transfected with human granzyme B cDNA, but not with granzyme H expressed in an identical fashion. Western blotting on Percoll-fractionated IL-2 activated human peripheral blood lymphocyte lysates and YT demonstrated reactivity of the monoclonal antibody with a approximately 32kDa species only in those fractions with granzyme A (BLT esterase) and B (Asp-ase) activities. Moreover, 2C5/1D10 antibodies coupled to Protein A-sepharose beads immunoprecipitated enzymatically active granzyme B from YT cell lysates. Scale up of this procedure should yield a means of purifying the large quantities of natural or recombinant granzyme B required to study the function of this granzyme in cellular cytotoxicity.

Human NK cells can be generated in vitro from CD34+Lin− bone marrow (BM) cells in long term cultures supplemented with stem cell factor (SCF or c-kit ligand), Interleukin-1α (IL-1α), Interleukin-2 (IL-2) or Interleukin-7 (IL-7). However, only IL-2 differentiated cells show cytotoxicity against the NK-sensitive K562 cell line. The cytotoxic activity defect seen in IL-7 differentiated NK cells could be due in part to the: a) lack of expression of adhesion molecules essential for the formation of the effector:target conjugates or/and b) lack of perforin and granzymes mRNA and enzymatic activity. In previous studies our results shown that these cells express low levels of the adhesion molecules CD11a and CD18 when compared with IL-2 differentiated NK cells. The addition for one week of IL-2 or Interleukin-15 (IL-15) to IL-7 differentiated NK cells induced an increase in the expression of CD11a and CD18 to similar levels seen in IL-2 differentiated NK cells. This increase seems to be related with their increase inthe cytolytic activity suggesting that these cell surface markers are important for cell killing. NK cells have cytotoxic granules containing effector molecules like perforin and granzymes which are able to trigger pathways leading to DNA fragmentation and apoptosis on target cells. IL-7 differentiated NK cells express perforin and Granzyme A (GA) mRNA but not Hu-Met-1mRNA. We also detected by RT-PCR the expression of Granzyme B (GB) and Granzyme H (GH) mRNA in these cells. These results suggest that the defect seen in the cytotoxic activity in not due to lack of perforin or granzyme mRNA expression.

Cytotoxic lymphocytes, which include CD4+ and CD8+ T cells as well as NK cells, use the granule exocytosis pathway to kill virus-infected and tumor cells. Previous studies have characterized the expression of many genes in this pathway (e.g. perforin, granzyme A, granzyme B, etc.), although no reagent has been developed to measure granzyme C protein at the single-cell level. The murine granzyme C gene, orthologous to human granzyme H, lies 24.2Kb directly downstream from granzyme B in the granzyme B gene cluster. Recombinant granzyme C rapidly induces target cell death in a manner distinct from granzyme A- or B-induced death. To further understand the regulation and function of murine granzyme C, we developed a granzyme C-specific monoclonal antibody and used flow cytometry to examine the expression of granzyme C in resting and activated murine cytotoxic lymphocyte compartments. Naive CD4+ and CD8+ T cells express little or no granzyme C (0.1 + 0.1% of cells are positive). After activation of splenocytes with plate-bound CD3 and CD28 agonistic antibodies for 4 days, a small percentage of CD4+ (2.3 + 1.0% positive) and CD8+ (6.6 + 0.3% positive) T cells express granzyme C. However, only 24 hours later, almost all CD4+ (96.7 + 2.7%) and CD8+ (98.7 + 1.4%) T cells express granzyme C. Granzyme B co-staining revealed that granzyme B is detectable in both CD4+ and CD8+ T cells at least 48 hours before granzyme C is expressed. Furthermore, we employed a fully mismatched GVHD mouse model in order to examine T cell expression of granzymes B and C in vivo; similarly, granzyme B expression preceded granzyme C by at least 48 hours. In addition, CD4+Foxp3+ regulatory T cells also expressed granzyme C in this model. Murine NK cell granzyme C mRNA expression was assessed using Affymetrix microarrays (MOE430v2) at rest and following IL-15 activation. Resting NK cells express minimal granzyme C mRNA (mean gzmC probe set signal intensity + SD [n=3]): 356 + 202, which increased after IL-15 activation as follows: 4,180 + 1,106 (day 1), 60,788 + 8,455 (day 2), 167,448 + 26,398 (day 4), and 178,451+14,037 (day 6). Utilizing our granzyme C-specific mAb, we showed that very few resting murine NK cells express granzyme C protein (2.3 + 0.4% positive). Consistent with the mRNA data, the percentage of granzyme C-expressing NK cells was substantially increased after 3 days of IL-15 activation (88.8 + 5.2% positive). In contrast, granzyme B mRNA levels are high in resting NK cells (41,208 + 2,534), and increase only incrementally with IL-15 treatment (Fehniger et al., Immunity 2007 Jun;26(6):798–811). Granzyme B protein expression is controlled at a post-transcriptional level in NK cells, whereas granzyme C expression is transcriptionally regulated. Taken together, our findings show that the mouse granzyme B and C genes, despite being only 24.2Kb apart, are activated in cytotoxic lymphocytes with different kinetics; moreover, granzyme B and C protein abundance is controlled by completely different mechanisms in NK cells. These data suggest that the granzyme genes are differentially regulated in lymphocyte compartments, and that this regulation may be relevant for how cytotoxic lymphocytes function.

Previous studies have suggested that expanded T-cell clones are found in the blood of 59% of patients with multiple myeloma. These expanded T-cell clones are associated with prolonged overall survival and thus it has been suggested that they may have anti-tumor activity. We have previously reported similar T-cell clones exist in the peripheral blood of patients with Waldenstrom’s Macroglobulinemia (WM) by using flow cytometry to determine the T cell receptor (TCR) Vβ repertoire. Expanded T-cell clones were detected in 9 of 15 (60%) patient samples. Of the nine patients with TCR Vβ clones, four patients had multiple clones. The TCR Vβ clones were not identical, representing a variety of families across the TCR Vβ repertoire. We have previously found that while the TCRVβ+CD8+CD57 negative subset represents polyclonal populations, the CD57 positive subset represents either monoclonal or biclonal populations. By comparing the genetic profiling of these two subsets from a statistically significant gene list, two genes have been found to be highly upregulated in the CD57 negative polyclonal subset. These two genes are i.) SESN3, a member in the Sorting Nexin (SNX) protein family which is implicated in regulating membrane traffic capable of interaction with phosphatidylinositol-3-phosphate (10.4 fold, p=0.0241); ii.) Epstein-Barr virus induced gene 2 (lymphocyte-specific G protein-coupled receptor) EBI2 (7.4 fold, p=0.0207): This finding is in contrast to previous report that EBI2 is expressed in B-lymphocyte cell lines and in lymphoid tissues but not in T-lymphocyte cell lines or peripheral blood T lymphocytes. For the CD57 positive clonal T cell expansions, consistent with our previous reports, CD28 expression was found to be down regulated by 2.6 fold. There are two genes found to be highly upregulated. They are i.) Granzyme B (4.3 fold, p=0.0337) also called Cytotoxic T-lymphocyte proteinase 2. This enzyme is necessary for target cell lysis in cell-mediated immune responses through caspase-dependent apoptosis; ii.) Granzyme H, also called Cytotoxic T-lymphocyte proteinase and probably necessary for target cell lysis in cell-mediated immune responses. In summary, we have shown that CD57 positive clonal T cell populations exist in some patients with WM. Importantly, microarray results have indicated some genes and proteins that may related to better patients survival as previously demonstrated in patients with Multiple Myeloma.

Granzymes are highly specific proteases stored in secretory granule in T-cells and NK-cells. Five different granzymes are known in human (A, B, H, K and M). A and B are the best studied and both can induce apotosis when delivered to target cells. The role for granzyme H, K and M are principally unknown. We have studied the expression of granzymes in subsets of T-cells and NK-cells both in fresh circulating cells and cultured cells stimulated with IL-2, IL-15 and OKT3/antiCD28. Protein expression (biosynthesis/immunoprecipitation) and mRNA level (RT-PCR) was studied in parallel. This report focus on Granzyme A and K which are close relatives, both tryptases located 70 kb apart on chromosome 5. Granzyme A have the highest expression in NK-cells were granzyme K are barely detected. Granzyme K on the other hand have a particular high expression in CD8+ T cells. Stimulation with IL-2 or IL-15 give a strong upregulation of both enzymes in NK-cells. Stimulation of CD8+ T cells gives mainly upregulation of granzyme A. Fresh CD4+ T cells show very weak synthesis of granzymes but treatment with IL-2 or IL-15 give a clear upregulation of both granzyme A and K. T-cells (both CD4+ and CD8+) are highly responsive to stimulation with OKT3/anti CD28 producing granzyme B but not A and K. This rather discordant pattern of expression for granzyme A and K talks in favour of different modes of regulation and most likely different functions. A striking difference between granzyme A and K concern the propensity for granzyme A to be secreted into the culture medium after stimulation while this is not the case for granzyme K. The secreted form of granzyme A has a molecular weight slightly higher than the intracellular form indicating the presence of a proform. Secretion of granzymes to the extracellular medium is probably not only an in vitro phenomena since both granzyme A and B can be detected in serum from healthy individuals in picomolar concentrations. Moreover, significant elevation of granzyme levels in serum can bee seen in different diseases with activation of cellular immunity and in T- and NK-cells malignancies. We have previously reported that proforms of certain serine proteases including the five human granzymes have a downregulating activity on myeloid proliferation, a mechanism probably implicated in certain forms of neutropenia. We propose that secreted granzymes (especially A, B and H) constitute a part of T regulatory function working both locally at the site of inflammation and distantly via the circulation.

The granzyme/perforin pathway is a central pathway for lymphocyte-mediated killing in both the innate and adaptive immune systems. This pathway is important in a variety of host defenses, including viral clearance and tumor cell killing, and its dysregulation results in several human and rodent diseases. To date, the majority of reports in this field have concentrated on the functions of granzymes A and B. Recent reports, however, suggest that the non-A/non-B 'orphan' granzymes found in both humans and mice are potentially significant. Although the functions of these orphan granzymes have yet to be fully established, initial data suggests their importance in both immune and nonimmune cells.