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Chimerism test was evaluated to predict leukemia relapse. Increasing mixed chimerism (IMC), defined as recipient increase ≥0.1% in peripheral blood total cell chimerism, was used as a surrogate of disease activity. Combination of quantitative PCR and short-tandem repeat method was applied to achieve high assay sensitivity. Total of 184 patients received stem cell transplant for acute myeloid leukemia (N = 110), acute lymphocytic leukemia (N = 41), myelodysplastic syndrome (N = 30), and 2389 chimerism tests (median follow-up, 1054 days). Sixty-six patients relapsed, and 118 patients did not. Cumulative incidence of relapse increased after 1 IMC or ≥2 consecutive IMCs (hazard ratios, 9.9 and 44.4, respectively). Predicted percentage relapse by day 30 after IMC was 0% (0 IMC), 10% (1 IMC), and 40% (≥2 IMCs). The last chimerism results before relapse detected IMC in 57 of 66 relapsed patients (sensitivity, 86.4%). Nine patients had no IMC before relapse (false negative) because of rapidly evolving relapse (N = 4) or extramural relapse (N = 5). In 118 patients without relapse, 158 of 1873 tests detected IMC (false positive, 8.4%; specificity, 91.6%). The false-positive rates increased with higher percentage recipient T-cell chimerism levels, indicating T-cell contamination as a cause. Chimerism monitoring predicts relapse. However, caution must be taken for false-positive or false-negative IMCs. T-cell removal can improve chimerism test specificity in patients with mixed T-cell chimerism., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Primary graft failure (PGF) and multi-lineage cytopenia (MLC) increase the risk of nonrelapse mortality in allogeneic hematopoietic cell transplants (HCT). We evaluated the impact of post-transplant cyclophosphamide (PTCy) and splenomegaly on PGF and MLC for hematological malignancies. This study included patients with PTCy (N=84) and conventional graft-vs.-host disease prophylaxis (N=199). The occurrence of splenomegaly varied widely, ranging from 17.1 % (acute myeloid leukemia) to 66.7 % (myeloproliferative neoplasms). Ten patients (N=8 in the PTCy and N=2 in the non- PTCy) developed PGF, and 44 patients developed MLC (both N=22). PTCy and severe splenomegaly (≥20 cm) were risk factors for PGF (odds ratio (OR): 10.40, p<0.01 and 6.74, p=0.01 respectively). Moreover, severe splenomegaly was a risk factor for PGF in PTCy patients (OR: 10.20, p=0.01). PTCy (hazard ratio (HR) 2.09, p=0.02), moderate (≥15, <20 cm, HR 4.36, p<0.01), and severe splenomegaly (HR 3.04, p=0.01) were independent risk factors for MLC. However, in subgroup analysis in PTCy patients, only mild splenomegaly (≥12, <15 cm, HR 4.62, p=0.01) was a risk factor for MLC. We recommend all patients be screened for splenomegaly before HCT, and PTCy is cautioned in those with splenomegaly., Competing Interests: Declaration of Competing Interest All authors declare no conflicts of interest associated with this manuscript., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Bacterial prophylaxis with a fluoroquinolone (FQ) during autologous stem cell transplant (ASCT) is common, although not standardized among transplant centers. The addition of doxycycline (doxy) to FQ prophylaxis was previously linked to reduced neutropenic fever and bacteremia in multiple myeloma (MM) patients undergoing ASCT although several confounders were present. We compared the incidence of neutropenic fever and bacteremia between MM patients variably receiving prophylaxis with FQ alone and FQ-doxy during ASCT., Methods: Systematic retrospective chart review of MM patients who underwent ASCT between January 2016 and December 2021. The primary objective was to determine the effect of bacterial prophylaxis on neutropenic fever and bacteremia within 30 days of ASCT. Multivariable logistic regression for neutropenic fever and univariate logistic regression for bacteremia accounted for differences in subject characteristics between groups., Results: Among 341 subjects, 121 received FQ and 220 received FQ-doxy for prophylaxis. Neutropenic fever developed in 67 (55.4%) and 87 (39.5%) subjects in the FQ and FQ-doxy groups, respectively (p = .005). Bacteremia was infrequent, with 5 (4.1%) and 5 (2.3%) cases developing in the FQ and FQ-doxy groups, respectively (p = .337). Among Gram-negative bacteremia events, 7/7 Escherichia coli strains were FQ-resistant, and 5/7 were ceftriaxone-resistant., Conclusion: The FQ-doxy prophylaxis group had fewer cases of neutropenic fever than the FQ group, however, there was no significant difference in bacteremia. High rates of antibiotic resistance were observed. An updated randomized controlled trial investigating appropriate prophylaxis for ASCT in the context of current oncology standards and changing antimicrobial resistance rates is warranted., (© 2024 The Authors. Transplant Infectious Disease published by Wiley Periodicals LLC.)

Full donor T-cell chimerism (FDTCC) after allogeneic stem cell transplant (allo-SCT) has been associated with improved outcomes in hematologic malignancy. We studied if donor human leukocyte antigen (HLA) mismatch improves achievement of FDTCC because mismatched HLA promotes donor T-cell proliferation where recipient T-cells had been impaired by previous treatment. Patients (N = 138) received allo-SCT with reduced-intensity conditioning (RIC) from 39 HLA mismatched donors (16 unrelated; 23 haploidentical) with post-transplant cyclophosphamide (PTCy) or 99 matched donors (21 siblings; 78 unrelated) with PTCy (N = 18) or non-PTCy (N = 81). Achievement of FDTCC by day 100 was higher with HLA mismatched donors than matched donors (82.1% vs. 27.3%, p < 00,001), which was further improved with 200 cGy total body irradiation (87.9%) or lymphoid (versus myeloid) malignancy (93.8%). Since all mismatched transplants used PTCy, FDTCC was higher with PTCy than non-PTCy (68.4% vs. 25.7%, p < 0.00001), but not in the matched transplant with PTCy (38.9%), negating PTCy as the primary driver. Lymphocyte recovery was delayed with PTCy than without (median on day + 30: 100 vs. 630/µL, p < 0.0001). The benefit of FDTCC was not translated into survival outcomes, especially in myeloid malignancies, possibly due to the insufficient graft-versus-tumor effects from the delayed lymphocyte recovery. Further studies are necessary to improve lymphocyte count recovery in PTCy transplants., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Preclinical data demonstrated that combining an anti-programmed cell death 1 (PD-1) inhibitor with a cyclin-dependent kinase 9 (CDK9) inhibitor provided enhanced antitumor activity with no significant toxicities, suggesting this combination may be a potential therapeutic option. The multicohort, phase 1 KEYNOTE-155 study evaluated the safety and antitumor activity of the PD-1 inhibitor pembrolizumab plus the CDK9 inhibitor dinaciclib in patients with relapsed or refractory (rr) chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL) and multiple myeloma (MM). Patients enrolled were ≥18 years of age with a confirmed diagnosis of CLL, DLBCL, or MM. The study included 2 phases: a dose-evaluation phase to determine dose-limiting toxicities and a signal-detection phase. Patients received pembrolizumab 200 mg every 3 weeks plus dinaciclib 7 mg/m2 on day 1 and 10 mg/m2 on day 8 of cycle 1 and 14 mg/m2 on days 1 and 8 of cycles 2 and later. Primary endpoint was safety, and a key secondary endpoint was objective response rate (ORR). Seventy-two patients were enrolled and received ≥1 dose of study treatment (CLL, n = 17; DLBCL, n = 38; MM, n = 17). Pembrolizumab plus dinaciclib was generally well tolerated and produced no unexpected toxicities. The ORRs were 29.4% (5/17, rrCLL), 21.1% (8/38, rrDLBCL), and 0% (0/17, rrMM), respectively. At data cutoff, all 72 patients had discontinued treatment, 38 (52.8%) because of progressive disease. These findings demonstrate activity with combination pembrolizumab plus dinaciclib and suggest that a careful and comprehensive approach to explore anti-PD-1 and CDK9 inhibitor combinations is warranted. This trial was registered at www.clinicaltrials.gov as NCT02684617., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Acute myeloid leukemia (AML) relapse after allogeneic stem cell transplant (alloSCT) remains a major therapeutic challenge. While patients with longer remission after initial alloSCT are recommended to receive cell therapy (CT) such as 2 nd alloSCT or donor lymphocyte infusion (DLI), survival for patients who relapse within 6 months of alloSCT has been dismal. We evaluated the outcomes of AML relapse after alloSCT to assess the impact of different treatments on long-term survival. One hundred and seventy-two patients with AML underwent alloSCT at the Penn State Cancer Institute from January 2014 to August 2019. Sixty-nine patients relapsed (median age, 60 years; range, 10-75). Of these, 4 patients underwent 2 nd alloSCT, and 26 received DLI. One-year overall survival (OS) in all cases was 20.3% (95% CI: 11.8-30.4%). Patients with ECOG performance status (PS) 0-2 at relapse showed a better 1-year OS than those with PS 3-4. Median OS for patients who received chemotherapy only or chemotherapy with CT was 74 or 173.5 days, respectively (p < 0.001). Relapsed patients receiving conventional re-induction chemotherapy were categorized as the high-intensity chemotherapy (H) group, while those receiving treatments such as hypomethylating agents or targeted agents were categorized as the low-intensity chemotherapy (L) group. The H group showed a better 1-year OS compared with the L group. Patients who received H + CT showed a better 1-year OS of 52.9% than the other 3 groups (p < 0.001). Even for patients with post-alloSCT remission duration of less than 6 months, the statistical significance was preserved. Factors including age, donor source at 1 st alloSCT, time to relapse, blast counts, PS at relapse, and treatment type after post-alloSCT relapse were used for a multivariate analysis, and matched or mismatched related donor and H + CT after alloSCT were identified as independent factors associated with OS. These findings support the use of H + CT as the treatment option of choice for AML patients who relapse after alloSCT when feasible., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Chimerism testing by short tandem repeats (STRs) is used to monitor engraftment after allogeneic hematopoietic stem cell transplantation (HSCT). Generally, STR alleles are stable and transferred from parent to child or from donor to recipient. However, 3 cases did not follow this norm. Additional work-up with help from forensic literature solved these mysteries. In case 1, the patient received HSCT from his son. The son shared STR alleles in 22/23 loci except Penta E, which was explained by repeat expansion in the son. In case 2, the patient had been in remission for 14 years after HSCT for lymphoma and developed repeat expansion in CSF1PO in granulocytes. In case 3, a pre-HSCT patient demonstrated 3 alleles, with 2 peaks taller than the third, in the FGA locus (chromosome 4). A combination of a triallelic variant and leukemia-associated trisomy 4 explained the finding. STR number variants are rare and clinically inconsequential but can overlap malignancy-associated, clinically significant changes., (© American Society for Clinical Pathology 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

High-dose cytarabine (HiDAC) consolidation for acute myeloid leukemia (AML) induces transient profound myelosuppression and potential morbidity/mortality. PrE0901 was a phase I multi-center trial evaluating the safety/toxicity of eltrombopag in AML patients receiving HiDAC consolidation. We used a standard 3 + 3 design employing a unique dose-escalation/de-escalation strategy. One hundred four patients were screened, 54 declined participation, 35 were deemed medically ineligible, and 14 were treated on study. Three patients were treated in cohorts 1-4 and two were treated in cohort 5. Eltrombopag + HiDAC was well-tolerated and no dose-limiting toxicities were observed. Median time to platelet recovery of all patients treated was 22.5 (range 16-43) days. Observationally, eltrombopag 150 mg once daily starting on day 3 of consolidation demonstrated the fastest and most consistent platelet recovery (median 19 days). Further investigation is needed to define the optimal role, dose, and schedule of eltrombopag in the treatment of chemotherapy associated myelosuppression.

We analyzed late fatal infections (LFIs) in allogeneic stem cell transplantation (HCT) recipients reported to the Center for International Blood and Marrow Transplant Research. We analyzed the incidence, infection types, and risk factors contributing to LFI in 10,336 adult and 5088 pediatric subjects surviving for ≥2 years after first HCT without relapse. Among 2245 adult and 377 pediatric patients who died, infections were a primary or contributory cause of death in 687 (31%) and 110 (29%), respectively. At 12 years post-HCT, the cumulative incidence of LFIs was 6.4% (95% confidence interval [CI], 5.8% to 7.0%) in adults, compared with 1.8% (95% CI, 1.4% to 2.3%) in pediatric subjects; P < .001). In adults, the 2 most significant risks for developing LFI were increasing age (20 to 39, 40 to 54, and ≥55 years versus 18 to 19 years) with hazard ratios (HRs) of 3.12 (95% CI, 1.33 to 7.32), 3.86 (95% CI, 1.66 to 8.95), and 5.49 (95% CI, 2.32 to 12.99) and a history of chronic graft-versus-host disease GVHD (cGVHD) with ongoing immunosuppression at 2 years post-HCT compared with no history of GVHD with (HR, 3.87; 95% CI, 2.59 to 5.78). In pediatric subjects, the 3 most significant risks for developing LFI were a history of cGVHD with ongoing immunosuppression (HR, 9.49; 95% CI, 4.39 to 20.51) or without ongoing immunosuppression (HR, 2.7; 95% CI, 1.05 to 7.43) at 2 years post-HCT compared with no history of GVHD, diagnosis of inherited abnormalities of erythrocyte function compared with diagnosis of acute myelogenous leukemia (HR, 2.30; 95% CI, 1.19 to 4.42), and age >10 years (HR, 1.92; 95% CI, 1.15 to 3.2). This study emphasizes the importance of continued vigilance for late infections after HCT and institution of support strategies aimed at decreasing the risk of cGVHD., (Copyright © 2018. Published by Elsevier Inc.)

We recently conducted a randomized double-blind study in which we demonstrated that moderate/severe chronic graft-versus-host disease (cGVHD) but not cGVHD-free survival was reduced in patients receiving anti-T lymphocyte globulin (ATLG) versus placebo. In a companion study we performed immunophenotypic analysis to determine the impact of ATLG on immune reconstitution (IR) and to correlate IR with clinical outcomes. The randomized study (n = 254) included patients (aged 18 to 65 years) who underwent myeloablative transplants for acute myeloid leukemia, myelodysplastic syndrome, or acute lymphoblastic leukemia from HLA-matched unrelated donors. Ninety-one patients consented for the companion IR study (ATLG = 44, placebo = 47). Blood samples were collected on days 30, 100, 180, and 360 after hematopoietic cell transplantation (HCT), and multiparameter flow cytometry was performed in a blinded fashion. Reconstitution of CD3 + and CD4 + T cells was delayed up to 6 months post-HCT in the ATLG arm, whereas absolute regulatory T cell (Treg) (CD4 + 25 + 127-) numbers were lower only in the first 100 days. Analysis of the CD4 + Treg and conventional T cells (Tconv) (CD4 + 25 - 127 + ) compartments showed a profound absence of naive Tregs and Tconv in the first 100 days post-HCT, with very slow recovery for 1 year. B cell and natural killer cell recovery were similar in each arm. Higher absolute counts of CD3 + , CD4 + , CD8 + T, Tregs, and Tconv were associated with improved overall survival, progression-free survival, and nonrelapse mortality but not moderate/severe cGVHD. Although ATLG delays CD3 + and CD4 + T cell recovery post-transplant, it has a relative Treg sparing effect after the early post-HCT period, with possible implications for protection from cGVHD. ATLG severely compromises the generation of naive CD4 + cells (Treg and Tconv), potentially affecting the diversity of the TCR repertoire and T cell responses against malignancy and infection., (Copyright © 2018 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Purpose Several open-label randomized studies have suggested that in vivo T-cell depletion with anti-T-lymphocyte globulin (ATLG; formerly antithymocyte globulin-Fresenius) reduces chronic graft-versus-host disease (cGVHD) without compromising survival. We report a prospective, double-blind phase III trial to investigate the effect of ATLG (Neovii Biotech, Lexington, MA) on cGVHD-free survival. Patients and Methods Two hundred fifty-four patients 18 to 65 years of age with acute leukemia or myelodysplastic syndrome who underwent myeloablative HLA-matched unrelated hematopoietic cell transplantation (HCT) were randomly assigned one to one to placebo (n =128 placebo) or ATLG (n = 126) treatment at 27 sites. Patients received either ATLG or placebo 20 mg/kg per day on days -3, -2, -1 in addition to tacrolimus and methotrexate as GVHD prophylaxis. The primary study end point was moderate-severe cGVHD-free survival. Results Despite a reduction in grade 2 to 4 acute GVHD (23% v 40%; P = .004) and moderate-severe cGVHD (12% v 33%; P < .001) in ATLG recipients, no difference in moderate-severe cGVHD-free survival between ATLG and placebo was found (2-year estimate: 48% v 44%, respectively; P = .47). Both progression-free survival (PFS) and overall survival (OS) were lower with ATLG (2-year estimate: 47% v 65% [ P = .04] and 59% v 74% [ P = .034], respectively). Multivariable analysis confirmed that ATLG was associated with inferior PFS (hazard ratio, 1.55; 95% CI, 1.05 to 2.28; P = .026) and OS (hazard ratio, 1.74; 95% CI, 1.12 to 2.71; P = .01). Conclusion In this prospective, randomized, double-blind trial of ATLG in unrelated myeloablative HCT, the incorporation of ATLG did not improve moderate-severe cGVHD-free survival. Moderate-severe cGVHD was significantly lower with ATLG, but PFS and OS also were lower. Additional analyses are needed to understand the appropriate role for ATLG in HCT.

Complement is one of the most important parts of the innate immune system. Some bacteria can gain resistance against the bactericidal action of complement by decorating their outer cell surface with lipopolysaccharides (LPSs) containing a very long O-antigen or with specific outer membrane proteins. Additionally, the presence of sialic acid in the LPS molecules can provide a level of protection for bacteria, likening them to human cells, a phenomenon known as molecular mimicry. Salmonella O48, which contains sialic acid in the O-antigen, is the major cause of reptile-associated salmonellosis, a worldwide public health problem. In this study, we tested the effect of prolonged exposure to human serum on strains from Salmonella serogroup O48, specifically on the O-antigen length. After multiple passages in serum, three out of four tested strains became resistant to serum action. The gas-liquid chromatography/tandem mass spectrometry analysis showed that, for most of the strains, the average length of the LPS O-antigen increased. Thus, we have discovered a link between the resistance of bacterial cells to serum and the elongation of the LPS O-antigen., Competing Interests: The authors declare no conflicts of interest.

Prognosis of leukemia relapse post allogeneic stem cell transplantation (alloSCT) is poor and effective new treatments are urgently needed. T cells are pivotal in eradicating leukemia through a graft versus leukemia (GVL) effect and leukemia relapse is considered a failure of GVL. T-cell exhaustion is a state of T-cell dysfunction mediated by inhibitory molecules including programmed cell death protein 1 (PD-1) and T-cell immunoglobulin domain and mucin domain 3 (TIM-3). To evaluate whether T-cell exhaustion and inhibitory pathways are involved in leukemia relapse post alloSCT, we performed phenotypic and functional studies on T cells from peripheral blood of acute myeloid leukemia patients receiving alloSCT. Here we report that PD-1(hi)TIM-3(+) cells are strongly associated with leukemia relapse post transplantation. Consistent with exhaustion, PD-1(hi)TIM-3(+) T cells are functionally deficient manifested by reduced production of interleukin 2 (IL-2), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). In addition, these cells demonstrate a phenotype consistent with exhausted antigen-experienced T cells by losing TN and TEMRA subsets. Importantly, increase of PD-1(hi)TIM-3(+) cells occurs before clinical diagnosis of leukemia relapse, suggesting their predictive value. Results of our study provide an early diagnostic approach and a therapeutic target for leukemia relapse post transplantation.

Background: Clofarabine, a second-generation nucleoside analogue, was studied in combination with etoposide and mitoxantrone in acute leukemia., Patients and Methods: In the phase I portion of this study clofarabine was given 20 or 25 mg/m(2) daily for 5 days (Days 2-6) with etoposide 100 mg/m(2) from day 1 to 5 and mitoxantrone 8 mg/m(2) from day 1 to 3. The dose-limiting toxicity was myelosuppression, and dose level 1, with clofarabine 20 mg/m(2) daily for 5 days was identified as the phase 2 dose. In total, 22 patients with relapsed or refractory acute myeloid leukemia (n = 18) and acute lymphocytic leukemia (n = 4) were treated., Results: Five of 22 patients (23%) achieved complete response (CR), and 3 (13%) achieved CR with incomplete platelet recovery; an overall response rate of 36%. Median overall survival was 167 days (range, 22-1327 days). For 2 patients this regimen represented an effective bridge to allogeneic stem cell transplantation., Conclusion: Clofarabine in combination with etoposide and mitoxantrone is tolerable and shows significant activity in relapsed and refractory acute leukemia in adults., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: The early diagnosis of the nephrotoxic effect of xenobiotics and drugs is still an unsolved problem. Recent studies suggest a correlation between the nephrotoxic activity of xenobiotics and increased concentration of amino acids in urine. The presented study was focused on the application of GLC-MS method for amino acids profiling in human urine as a noninvasive method for monitoring of kidney condition and tubular injury level., Material and Methods: The analytic method is based on the conversion of the amino acids present in the sample to tert-butyldimethylsilyl (TBDMS) derivatives and their analysis by gas-liquid chromatography-mass spectrometry (GLC-MS). The procedure of urine sample preparation for chromatographic analysis was optimized., Results: The presence of 12 amino acids in most of the tested healthy human urine samples was detected. The significant differences in the levels of particular amino acids between patients with tubular injury and healthy controls were found, especially for lysine, valine, serine, alanine and leucine (on average 30.0, 7.5, 3.6, 2.9 and 0.5 fold respectively)., Conclusions: We found that this approach based on GLC-MS detection can be used in nephrotoxicity studies for urine amino acids monitoring in exposure to xenobiotics and drugs.

There is little data comparing the activity and toxicity of donor lymphocyte therapy with granulocyte (G)-CSF-mobilized cells (G-donor lymphocyte infusion (DLI)) with the conventionally collected DLI (C-DLI) after allogeneic blood or marrow transplantation. We retrospectively evaluated 67 patients to compare the efficacy and toxicity of GCSF-mobilized DLI with C-DLI in the treatment of relapse of malignant disease or poor donor engraftment post transplant. We assessed clinical outcomes that may represent the immunological outcome of DLI. The median OS was 210 days (range 3-2436 days), 291 days (range 17-1491 days) in the G-DLI group (15 patients) and 207.5 days (range 3-2436 days) in the C-DLI group (52 patients). The median PFS time was 72 days (range 8-1491 days) in the G-DLI group vs 82 days (range 1-2436 days) in the C-DLI group. Rates of post DLI GVHD and improvement in donor engraftment were similar in the G-DLI and C-DLI groups. We conclude that G-DLI appears to have similar therapeutic activity to that seen with C-DLI, and where such cells are available they may be substituted for conventional donor lymphocytes.

Tumour progression is continuously driven by a sequence of genetic events. The presence of mutant or activated Ras proteins represents an interesting paradigm for the investigation of oncogene-dependent induction of tumour angiogenesis. These genes are widely distributed in human cancers. Previously we have shown that cells harbouring mutant H-Ras release soluble unidentified factor(s) associated with lowered expression of an angiogenesis inhibitor - Thrombospondin-1 - (TSP-1) in adjacent normal tissue. In this study, we have addressed the question as to whether or not introduction of the H-ras oncogene leads to increased production of sphingosine. To assess the amount of sphingosine in conditioned media, we developed a technique based on sphingolipid isolation and GC-MSMS detection of specific silylated sphingosine derivatives. Cells harbouring mutant H-Ras, release significant amounts of sphingosine in contrast to normal isogenic cells or premalignant cells. Increased concentration of sphingosine in conditioned media was correlated with their ability to down-regulate the expression of TSP-1. Moreover, medium collected in the presence of U0126, an inhibitor of MAPK kinase (MEK), contained undetectable amounts of sphingosine and had no ability to down-regulate TSP-1 expression. Overall, our studies suggest a H-Ras-dependent mechanism of changing the equilibrium of angiogenic factors in favour of induction of angiogenesis, where a central role is played by sphingosine, a low molecular entity. This represents an example of how a mechanism of translating genetic changes within transformed cells could be amplified into a much larger effect involving the tumour parenchyma and stroma, and this could greatly in turn accelerate local tumour growth and metastasis., (© 2012 The Authors. International Journal of Experimental Pathology © 2012 International Journal of Experimental Pathology.)

High-dose melphalan is considered the current standard of care among the preparative regimens used in peripheral blood autologous SCT (ASCT) for multiple myeloma (MM). We report the results of a single ASCT in 79 MM patients using the BU/CY conditioning regimen, with BU 1 mg/kg p.o. or 0.8 mg/kg i.v. every 6 h x 16 doses, and CY 60 mg/kg per day i.v. for 2 days. ASCT was carried out in first (62%) or subsequent remission/refractory disease (38%). For an overall RR of 86%, 48 and 20 patients achieved PR and CR, respectively. At a median follow-up of 41 months (range 2-132 months), the estimated median OS and PFS were 45 months (95% confidence interval (CI)=38-92) and 20 months (95% CI=15-25), respectively. The BU/CY regimen was well tolerated, and transplant-related mortality was 4%. Clinical outcomes of the BU/CY regimen are not superior to those obtained in historical controls with high-dose melphalan followed by a single ASCT. Therefore, considering even the greater complexity of administration of the BU/CY regimen compared with that of single-agent melphalan, we believe the latter should remain the conditioning regimen of choice for ASCT in MM.

Bone marrow cells have the capacity to contribute to distant organs. We show that marrow also contributes to epithelial neoplasias of the small bowel, colon, and lung, but not the skin. In particular, epithelial neoplasias found in patients after hematopoietic cell transplantations demonstrate that human marrow incorporates into neoplasias by adopting the phenotype of the surrounding neoplastic environment. To more rigorously evaluate marrow contribution to epithelial cancer, we employed mouse models of intestinal and lung neoplasias, which revealed specifically that the hematopoietic stem cell and its progeny incorporate within cancer. Furthermore, this marrow involvement in epithelial cancer does not appear to occur by induction of stable fusion. Whereas previous claims have been made that marrow can serve as a direct source of epithelial neoplasia, our results indicate a more cautionary note, that marrow contributes to cancer as a means of developmental mimicry. Disclosure of Potential Conflicts of Interest is found at the end of this article.

Non-myeloablative conditioning has extended the use of allogeneic haematopoietic transplant to many previously ineligible patients. We added the immunosuppressive and antitumour agent sirolimus (rapamycin) to an established transplant regimen of fludarabine 25 mg/m(2) days -7 through -3 and cyclophosphamide 1000 mg/m(2) days -7 and -6, with tacrolimus and methotrexate immunoprophyllaxis. A total of 23 patients with acute myelogenous leukaemia (AML) were treated, with a median age of 59 years (range: 28-72) at transplant. Only seven patients in total were in complete remission prior to transplantation. Nine patients were in chemotherapy-refractory progression and seven were primarily refractory to induction therapy. Six patients received matched sibling, 11 unrelated donor, 1-5/6 matched and five haploidentical (haplo - three of six or four of six matched) transplants. The haplo-recipients also received antithymocyte globulin, all patients engrafted. Only two, both recipients of haploidentical cells, have died from transplant-related causes. Twelve of 23 patients survived at 198-1162-d post-transplant (median 578). Four of 12 survivors relapsed at 83, 88, 243 and 508 d and three were in remission after chemotherapy and donor lymphocyte infusion. Although follow up is short, this data suggests that non-myeloablative haematopoietic cell transplantation with sirolimus (rapamycin)-based immunosuppression may provide disease control over several years in some patients with advanced and poor prognosis AML.

Relapse after high-dose chemotherapy is the main cause of therapeutic failure in patients with metastatic breast cancer. Adoptive immunotherapy with interleukin-2 (IL-2) plus activated natural killer cells may eliminate residual disease without excessive toxicity. The authors sought to determine if immunotherapy immediately after transplantation would affect engraftment and the toxicity associated with transplantation. Fifteen consecutive patients with metastatic breast cancer were allocated to three cohorts. Cohort 1 (five patients) received high-dose cyclophosphamide, thiotepa, and carboplatin (CTCb) followed by peripheral blood stem cell infusion and granulocyte colony-stimulating factor at 10 micrograms/kg. Cohort 2 (five patients) received in addition rhIL-2 (2 x 10(6) IU/m2/day) for 4 days intravenously via continuous infusion after peripheral blood stem cell infusion. In cohort 3 (five patients), peripheral blood stem cell transplant was followed by infusion of autologous activated NK cells and rhIL-2 (2 x 10(6) IU/m2/day) for 4 days (via continuous intravenous infusion). Generation of activated NK cells was possible in all patients in cohort 3. All patients has successful engraftment. Median time to absolute neutrophil count more than 0.5 x 10(9)/L was 8 days (range, 8 to 11 days) in cohort 1, 9 days (range, 7 to 11 days) in cohort 2, and 9 days (range, 8 to 9 days) in cohort 3. Median time until the platelet count was more than 20 x 10(9)/L was 14 days (range, 9 to 22 days) in cohort 1, 11 days (range, 6 to 14 days) in cohort 2, and 12 days (range, 11 to 21 days) in cohort 3. All patients developed neutropenic fevers, but the overall toxicity associated with the infusion of IL-2 (cohort 2) or IL-2 plus activated NK cells (cohort 3) did not differ from that observed in cohort 1. Complete responses were achieved in one patient in cohort 1, in two patients in cohort 2, and in one patient in cohort 3. In conclusion, post-transplant adoptive immunotherapy with activated NK cells plus IL-2 is feasible, well tolerated, and does not adversely affect engraftment.

This case is presented to challenge the reader to formulate a differential diagnosis for a patient who visits the dentist with spontaneous, continuous gingival bleeding. When this situation occurs, it is serious and requires immediate attention and a specific treatment plan to arrive at the underlying diagnosis and control the bleeding. The signs and symptoms of a patient with gingival bleeding are presented for diagnosis; the history and management are detailed, and may be useful in diagnosing and treating similar patients.

Factors influencing mobilization and engraftment of PBSC were analyzed in 38 patients with metastatic breast cancer who were undergoing PBSC transplantation. None of these patients had had previous chemotherapy for metastatic disease. PBSC were mobilized with cyclophosphamide (CY) and G-CSF (n = 21) or CY and etoposide (CY-etoposide) and G-CSF (n = 17). All received cyclophosphamide 6000 mg/m2, thiotepa 500 mg/m2, and carboplatin 800 mg/m2 (CTCb) as preparative regimen. PBSC infusion was followed by G-CSF at 5 microg/kg in 30 patients or 10 microg/kg in 8 patients. A median number of 27 x 10(6) CD34+ cells/kg was obtained with a median of four aphereses. Previous chemotherapy, radiation therapy, marrow disease, time from previous chemotherapy to mobilization, and type of mobilization regimen did not have a statistically significant effect on collection efficiency (CE). CE was defined as the total number of CD34+ collected/number of collections. Engraftment was rapid, with patients reaching a neutrophil count of 0.5 x 10(9)/L a median of 9 days (range 7-23) and a platelet count of 20 x 10(9)/L a median of 12 days (range 8-28) after transplantation. Shorter times to platelet recovery were associated with a higher number of CD34+ cells infused (p = 0.012), CY mobilization (p = 0.033), and a lower number of prior chemotherapy cycles (p = 0.022). When the number of CD34+ cells was included in the proportional hazard model, no other variables were found to be significant predictors of platelet engraftment. Time to neutrophil recovery was negatively associated with the dose of G-CSF used after transplantation (p = 0.036) CD34 cell dose is an important predictor of engraftment kinetics. A posttransplant dose of G-CSF improves neutrophil recovery. For patients with metastatic breast cancer and no previous chemotherapy for metastatic disease, we have no evidence for a difference between CY and CY-Etoposide as the mobilization regimen.

A 67 year old male developed a therapy related myelodysplastic process culminating in acute myeloid leukemia 16 years following initial treatment for a large cell lymphoma. A second relapse of this leukemia showed 12% blasts including numerous giant blasts. The presence of giant blasts suggested the possibility of relapsed malignant lymphoma, however, flow cytometry and immunohistochemistry identified them as myeloid and chromosomal analysis revealed a near-tetraploid cell line. No evidence of lymphoma was seen. Although remission was induced with chemotherapy he subsequently relapsed with marrow and/or CNS involvement and was maintained on palliative therapy until he developed sepsis and died, 13 months following the observation of tetraploidy and 33 months following the onset of acute leukemia.

A multistep HDC regimen was designed as first-line chemotherapy for MBC. Twenty-four patients with MBC and no previous chemotherapy for metastatic disease were treated with high-dose cyclophosphamide (5000 mg/m2), and etoposide (1000 mg/m2) (CyVP16), followed by granulocyte colony-stimulating factor (G-CSF). Peripheral blood stem cells (PBSCs) were collected. Subsequently patients received cyclophosphamide (6000 mg/m2), thiotepa (500 mg/m2) and carboplatin (800 mg/m2) (CTCb) with hematopoietic rescue. Upon recovery from hematopoietic and gastrointestinal toxicity three cycles of doxorubicin (50 mg/m2) and taxol (150 mg/m2) were delivered. After CyVP16 42% of patients developed neutropenic fevers. There was one documented episode of bacteremia. Patients received CTCb 32 days after starting CyVP16. After CTCb the median number of days to ANC >5 x 10(9)/l was 10 and to a platelet count >20 x 10(9)/l was 14. Neutropenic fevers developed in 16 patients. There were no hemorrhagic episodes. A total of 69 cycles of doxorubicin and taxol were delivered (87% of planned). The median time from PBSC infusion to the first cycle was 38 days. The median time to the second cycle was 27 days and to the last cycle was 24 days. One patient developed congestive heart failure. Two episodes of neutropenic fevers were observed. No toxicity-related deaths were observed. Grafts are stable at 6 months post transplantation. This multistep regimen is feasible with acceptable toxicity.

Transplantation of marrow from unrelated donors is associated with an increased incidence and severity of graft-versus-host disease (GVHD). In an attempt to minimize GVHD without compromising engraftment, unrelated donor marrow was depleted of lymphocytes by counterflow centrifugal elutriation (CCE), and a fixed dose of 0.5 x 10(6) CD3+ T cells/kg, as measured in real time by flow cytometry, was added back to the graft. Patients received cyclosporine (CYA) and corticosteroids for GVHD prophylaxis and to facilitate engraftment. In the first cohort (study I), 7 patients received busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) (CY) and one patient received CY (200 mg/kg) + 1260 cGy fractionated TBI. Of 6 who were evaluable for both engraftment and rejection, 4 rejected their graft. The study was terminated, and the protocol was modified (study II) by the addition of antithymocyte globulin (ATG) to the pre-BMT and post-BMT therapy. Twelve patients received CY + TBI as above plus ATG given pre-BMT and post-BMT. Ten of twelve who received ATG engrafted. Twelve patients from studies I and II were evaluable for acute GVHD. Two developed grade I acute GVHD. Two patients developed grade II acute GVHD, 2 patients developed grade III GVHD, and 1 patient developed grade IV acute GVHD. Two of three cases of acute GVHD (> grade II) occurred later than day 100 after BMT concomitant with reduction of immunosuppressive therapy. The rate of engraftment was significantly higher in study II (p = .054). In numbers of CD34+ cells infused, numbers of CFU-GM infused, and numbers of nucleated cells did not correlate with engraftment. We conclude that (a) in contrast to the results seen in recipients of marrow from HLA-matched sibling donors, the depletion of unrelated donor marrow of all but 0.5 x 10(6) CD34+ cells/kg together with CYA + corticosteroids was not sufficient to facilitate engraftment. The use of a more immunosuppressive regimen containing TBI and ATG appeared to improve engraftment. (b) The reduction of the graft T cell dose to 0.5 x 10(6) CD34+ cells/kg resulted in a higher incidence of acute GVHD than that seen in recipients of marrow from genotypically identical donors whose marrow was similarly processed.

A 32-year-old male received an allogeneic peripheral blood stem cell transplant (alloPBSCT) for myelodysplasia from his one HLA-A antigen mismatched brother. He is alive with trilineage engraftment and without active GVHD 200 days after transplant. In July 1986 he underwent orthotopic cardiac transplantation for viral cardiomyopathy and has received continuous immunosuppressive therapy. A post-transplant lymphoproliferative disorder with Hodgkin-like histopathology was diagnosed in August 1993 and was successfully treated with four cycles of MOPP chemotherapy. Due to persistent pancytopenia he underwent a bone marrow aspiration and biopsy in May 1996 which revealed monosomy 7 and morphologic changes compatible with myelodysplasia. This is the first report of a cardiac transplant recipient receiving an allogeneic hematopoietic stem cell transplant.

The combination of busulfan and cyclophosphamide has seldom been employed as a conditioning regimen for patients with lymphoma. Twenty patients with relapsed or refractory lymphoma were treated with busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) (BU/CY) followed by peripheral blood stem cell rescue in 19 patients or autologous bone marrow in one patient. There were 12 females and eight males, with a median age of 48 years (range 30-65). Four patients had Hodgkin's disease, and 16 patients had non-Hodgkin's lymphoma. Disease status at the time of BU/CY was: first relapse in 10 patients (four patients with chemosensitive disease and six patients with chemoresistant disease), primary refractory disease in six patients, and more advanced disease in four patients. Excessive treatment-related toxicity was not noted. There were no cases of interstitial pneumonitis, but three cases of veno-occlusive disease occurred. At 2 years, the estimated overall survival and event-free survival are 50% and 33%. We concluded that BU/CY seems to have sufficient antilymphoma activity, is devoid of excessive toxicity and warrants further investigation in this patient population.

High-dose chemotherapy is associated with a high complete response rate and possibly some survival advantage in patients with metastatic breast cancer. We designed a clinical trial consisting of a two-step high-dose chemotherapy regimen followed by posttransplantation doxorubicin as the first chemotherapy treatment for metastatic disease. Twenty-one patients with metastatic breast cancer and no previous chemotherapy for metastatic disease were treated with high-dose cyclophosphamide (Cy; 5000 mg/m2), followed by granulocyte colony-stimulating factor. Peripheral blood stem cells were collected. Subsequently, patients received Cy (6000 mg/m2), thiotepa (500 mg/m2), and carboplatin (800 mg/m2) (CTCb) with hematopoietic rescue. Upon recovery of hematopoietic and gastrointestinal toxicity, three cycles of doxorubicin (Dox; 60 mg/m2) were delivered. After Cy, nine patients (45%) developed neutropenic fevers. There were no episodes of bacteremia. Patients received CTCb 37 days after starting Cy and had a hospital stay of 19 days. After CTCb, the median number of days to an absolute neutrophil count >5 x 10(9)/liter was 8, and the median number of days to a platelet count >20 x 10(9)/liter was 9. Neutropenic fevers occurred in 12 patients. There were no hemorrhagic complications. Fifty-five of the 63 planned courses of Dox were delivered. The median time from peripheral blood stem cell infusion to the first Dox cycle was 38 days. The median time to the second Dox cycle was 28 days, and to the last cycle was 30 days. Three episodes of neutropenic fevers were observed. Two patients developed herpes zoster. This regimen is feasible, with acceptable toxicity.

We evaluated early and late hematopoietic reconstitution in 27 patients with advanced lymphoma, Hodgkin's disease, and breast or ovarian cancer after treatment using high-dose/myeloablative conditioning regimens and autologous peripheral blood stem cell PBSC) transplantation. Eighteen patients (67%) received G-CSF 5 micrograms/kg/day following chemotherapy and nine (33%) were mobilized using G-CSF alone. Each patient had 7 x 10(8) mononuclear cells (MNC) per kg collected. G-CSF was administered post-PBSC infusion. While all patients showed prompt granulocyte recovery by day 14, platelet recovery failed to occur in our (15%) heavily pretreated patients with non-Hodgkin's lymphoma. Retrospective analysis in 17 patients revealed that the infused number of CD34 surface antigen-positive cells correlated with time to granulocyte (r = 0.59, P = 0.012) and platelet (r = 0.58, P = 0.021) recovery. Patients receiving the higher numbers of CD34+ cells had consistently better hematologic parameters at 11 times examined. At 180 days post-transplant, the median Hb level was 124 g/l vs 88 g/l (P = 0.004); platelet count was 202 x 10(9)/l vs 25 x 10(9)/l (P = 0.004); and neutrophil count was 3100 x 10(6)/l vs 1400 x 10(6)/l (P = 0.15). Hemoglobin strongly correlated with the CD34+ cell dose at 360 days (r = 0.90, P = 0.01). We conclude that graft CD34+ cell content appears to be an indicator of the quality of late as well as early hematopoietic function.

Human herpesvirus 6 activity (HHV-6) was studied in 15 allogeneic and 11 autologous marrow transplantation patients. After transplantation, HHV-6 was isolated from the peripheral blood mononuclear cells of 12 of 26 patients (6 allogeneic and 6 autologous). All isolates were variant B. Eleven of 26 and 12 of 19 patients showed salivary shedding of HHV-6 DNA before and after transplantation, respectively. The antibody titer increased in 7 of 26 patients. Thus, 23 of 26 patients showed evidence of active HHV-6 infection either by virus isolation, salivary shedding, or increases in antibody titers. The fraction of saliva specimens positive in 19 patients was negatively associated with their antibody titers (P= .005). The proportion of cultures positive increased after transplantation (P = .007). Sinusitis was associated with HHV-6 isolation in autologous recipients (P= .002). In allogeneic patients, active human cytomegalovirus infection was associated with HHV-6 isolation (P = .04). No association was observed between HHV-6 infection and GVHD, pneumonia, delay in engraftment, or marrow suppression. Of the 120 clinical events analyzed in 26 patients, HHV-6 was defined as a probable cause of 16 events in 9 patients based on the propinquity of HHV-6 activity and the clinical event plus the absence of other identified causes of the event.

This study was designed to establish the toxicity and response rates o observed with a combination of high-dose cyclophosphamide, carboplatin, and etoposide with stem cell rescue in patients with breast carcinoma. Eligibility criteria included metastatic or locally advanced breast carcinoma ; aged < or equal to 60 years; performance status Eastern Cooperative Oncology Group (ECOG) 0-1; and creatinine clearance > or equal to 65 ml/min. Chemotherapy consisted of cyclophosphamide 25 mg/kg i.v. X 4 days, etoposide 400 mg/m(2) i.v. X 4 days, and carboplatin 375 mg/m(2) X 4 days. Bone marrow or peripheral blood stem cells were reinfused 48 h after completion of chemotherapy. Seventeen patients were treated in this study. The major toxicity was gastrointestinal (grades I and II). Fevers associated with neutropenia were observed in all the patients, but no episodes of bacteremia were documented. Hematopoietic toxicities were acceptable. No toxic deaths were observed. Six patients had chemotherapy-sensitive disease at time of transplant, nine had refractory disease, and two were untested. A response rate of 62% with 18% complete response (CR) was achieved. Two patients are free of disease at +7 and +9 months after transplantation. The combination of high-dose cyclophosphamide, carboplatin, and etoposide is well tolerated with a response rate comparable to previously reported high-dose chemotherapy regimens. However, in a poor prognostic risk group, namely patients with chemoinsensitive disease, this therapeutic approach seems to be of no advantage over standard chemotherapy.

Between July 1991 and January 1994, 52 patients with hematologic malignancies underwent BMT using BU/CY2 as conditioning regimen. Median patient age was 38 years. Eleven patients underwent autologous BMT, 22 HLA-identical allogeneic BMT, and 19 patients underwent a MUD or an allogeneic mismatched BMT. GVHD prophylaxis was with cyclosporine/methylprednisone in 26 patients; T cell depletion was used in 15 patients. VOD was observed in 7.5% of patients, IP in 12%, seizures in 4%. The overall incidence of grade II-IV acute GVHD was 35%. Delayed platelet engraftment was observed in seven of 11 patients who underwent autologous BMT. Graft failure was seen in seven of 19 (37%) patients who underwent MUD or allogeneic mismatched BMT. Six of the seven patients received T cell depletion as GVHD prophylaxis. BU/CY2 transplantation from an unrelated or family-mismatched donor with T cell depletion is associated with a high incidence of graft failure.

Hematopoietic effects of human Herpesvirus-6 (HHV-6) infection following bone marrow transplantation (BMT) include delayed engraftment and early myelosuppression. Variant A has not been isolated after BMT. A case of graft failure is reported following an HLA-identical BMT for chronic myelogenous leukemia (CML) in chronic phase. Evaluation of bone marrow during the period of graft failure revealed variants A and B of HHV-6 by culture, immunofluorescence, polymerase chain reaction (PCR), and immunohistochemistry. Evidence for other cases of graft failure, including cytomegalovirus (CMV), could not be found. A hypothesis is proposed that late graft failure in this case was due to variant A of HHV-6.

Relapse after high-dose chemotherapy supported by peripheral blood stem cell transplantation (HDC-PBSCT) is the main cause of therapeutic failure in patients with lymphoma and breast cancer. Adoptive immunotherapy with activated natural killer (A-NK) cells and interleukin 2 might eliminate surviving residual tumor without adding to toxicity. Eleven patients with relapsed lymphoma and one with metastatic breast cancer were entered on a pilot clinical trial of HDC-PBSCT followed on day 2 after transplant by infusion of cultured autologous A-NK cells. Simultaneously, recombinant human interleukin 2 (rhIL-2) was initiated as a 4-day continuous i.v. infusion at 2 x 10(6) IU/m2/day, referred to as high-dose rhIL-2. Therapy with high-dose rhIL-2 was followed by a 90-day continuous i. v. infusion at 3 x 10(5) IU/m2/day, referred to as low-dose rhIL-2. All patients engrafted and nine completed treatment. Posttransplant days to a neutrophil count of 500/microliter and to a platelet count of 50,000/microliter were similar to comparable patients treated with HDC-PBSCT alone. Generation of A-NK cells for therapy was feasible in all patients except the three patients with Hodgkin's disease, whose cells did not proliferate in culture. Overall toxicity associated with early posttransplant transfer of A-NK cells and interleukin 2 did not differ from that observed with peripheral blood stem cell transplantation alone in comparable patients. There was early amplification of natural killer cell activity in the peripheral blood of four patients that appeared to result from the transfused A-NK cells. Adoptive transfer of A-NK cells and rhIL-2 during the pancytopenic phase after HDC-PBSCT was feasible and well tolerated, did not adversely affect engraftment, and resulted in amplified natural killer activity in the peripheral blood during the immediate posttransplantation period.

While cadaveric vertebral bodies (VB) have long been proposed as a suitable source of bone marrow (BM) for transplantation (BMT), they have rarely been used for this purpose. We have infused VB BM immediately following whole organ (WO) transplantation to augment donor cell chimerism. We quantified the hematopoietic progenitor cell (HPC) content of VB BM as well as BM obtained from the iliac crests (IC) of normal allogenic donors (ALLO) and from patients with malignancy undergoing autologous marrow harvest (AUTO). Patients undergoing WO/BM transplantation also had AUTO BM harvested in the event that subsequent lymphohematopoietic reconstitution was required. Twenty-four VB BM, 24 IC BM-ALLO, 31 IC AUTO, and 24 IC WO-AUTO were harvested. VB BM was tested 12 to 72 hr after procurement and infused after completion of WO grafting. IC BM was tested and then used or cryopreserved immediately. HPC were quantified by clonal assay measuring CFU-GM, BFU-E, and CFU-GEMM, and by flow cytometry for CD34+ progenitor cells. On an average, 9 VB were processed during each harvest, and despite an extended processing time the number of viable nucleated cells obtained was significantly higher than that from IC. Furthermore, by HPC content, VB BM was equivalent to IC BM, which is routinely used for BMT. We conclude that VB BM is a clinically valuable source of BM for allogeneic transplantation.

Human umbilical cord blood (CB) is a rich source of hematopoietic stem cells for both research and stem cell transplantation. In clinical studies, it appears that recovery from myeloablative therapy using CB requires significantly fewer cells than a typical allogeneic marrow transplant. This suggests that CB may be enriched for early hematopoietic progenitors. The present studies were undertaken to determine the presence of CD34+ cells in CB with the phenotypic characteristics of multipotential stem cells. In 22 CB harvests, the average percentage of CD34+ cells was 1.33 +/- 0.21% (SE), a value similar to that in adult normal bone marrows (BM). However, the distribution of CD34+ cells was distinctly different from either BM or granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell harvests. CB contained a defined population of brightly staining CD34+ cells with low side scatter. These CD34 (bright) cells comprised a mean of 14.5 +/- 2.5% of the CB CD34+ cells, whereas < 1% of BM CD34+ cells has been shown to be CD34- bright. Eighty-five to ninety percent were negative for three antigens expressed at an early stage of stem cell maturation: CD38, HLA-DR and LFA-1. Fifty-five percent of these CD34 (bright) cells did not express the CD45RA isoform, an additional marker of immaturity. The antigen-bright cells also lacked lineage-specific antigens including CD33, CD56, CD19, CD10 and CD7 as well as CD71. Approximately 46% were Thy-1+, and 40% expressed c-kit receptors. These data suggest that, by phenotypic criteria, CB may be a particularly enriched source of primitive hematopoietic precursors.

We report the occurrence of reversible cyclosporine-induced cortical blindness in three allogeneic bone marrow transplant recipients. Possible mechanisms involved in this rare complication, as well as the associated radiographic and pathologic findings, are discussed.