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Background: The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection causes coronavirus disease-2019 (COVID-19) in some individuals, while the majority remain asymptomatic. Natural killer (NK) cells play an essential role in antiviral defense. NK cell maturation and function are regulated mainly by highly polymorphic killer cell immunoglobulin-like receptors (KIR) and cognate HLA class I ligands. Herein, we tested our hypothesis that the individualized KIR and HLA class I ligand combinations that control NK cell function determine the outcome of SARS-CoV-2 infection. Methods: We characterized KIR and HLA genes in 200 patients hospitalized for COVID-19 and 195 healthy general population controls. Results: The KIR3DL1+HLA-Bw4+ [Odds ratio (OR) = 0.65, p = 0.03] and KIR3DL2+HLA-A3/11+ (OR = 0.6, p = 0.02) combinations were encountered at significantly lower frequency in COVID-19 patients than in the controls. Notably, 40% of the patients lacked both of these KIR+HLA+ combinations compared to 24.6% of the controls (OR = 2.04, p = 0.001). Additionally, activating receptors KIR2DS1+KIR2DS5+ are more frequent in patients with severe COVID-19 than patients with mild disease (OR = 1.8, p = 0.05). Individuals carrying KIR2DS1+KIR2DS5+ genes but missing either KIR3DL1+HLA-Bw4+ combination (OR = 1.73, p = 0.04) or KIR3DL2+HLA-A3/11+ combination (OR = 1.75, p = 0.02) or both KIR3DL1+HLA-Bw4+ and KIR2DL2+HLA-A3/11+ combinations (OR = 1.63, p = 0.03) were more frequent in the COVID-19 cohort compared to controls. Conclusions: The absence of KIR3DL1+HLA-Bw4+ and KIR3DL2+HLA-A3/11+ combinations presumably yields inadequate NK cell maturation and reduces anti-SARS-CoV-2 defense, causing COVID-19. An increased frequency of KIR2DS1+KIR2DS5+ in severe COVID-19 patients suggests vigorous NK cell response triggered via these activating receptors and subsequent production of exuberant inflammatory cytokines responsible for severe COVID-19. Our results demonstrate that specific KIR-HLA combinations that control NK cell maturation and function are underlying immunogenetic variables that determine the dual role of NK cells in mediating beneficial antiviral and detrimental pathologic action. These findings offer a framework for developing potential host genetic biomarkers to distinguish individuals prone to COVID-19.

BackgroundPhase IIb clinical trial with isatuximab (Isa)-lenalidomide (Len)-dexamethasone (Dex) showed an improved progression-free survival (PFS) in patients with relapsed or refractory multiple myeloma (RRMM), but the efficacy varied by patient. Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) cells plays a crucial role in arbitrating antitumor activities of therapeutic-antibodies. We tested if patient-specific genetic makeup known to set NK cell functional threshold influence response to Isa-Len-Dex therapy.MethodsWe characterized 57 patients with RRMM receiving Isa-Len-Dex for polymorphisms of killer-cell immunoglobulin-like receptors (KIR), human leukocyte antigen (HLA) class I, and FCGR3A loci. In vitro ADCC assay, coincubating primary NK cells expressing specific KIR repertoire with multiple myeloma cell lines (MM cells) expressing selected HLA class I ligands, was used to confirm the identified genetic correlatives of clinical response.ResultsPatients with KIR3DL2+ and its cognate-ligand HLA-A3/11+ had superior PFS than patients missing this combination (HR=0.43; p=0.02), while patients carrying KIR2DL1+ and HLA-C2C2+ compared with to patients missing this pair showed short PFS (HR=3.54; p=0.05). Patients with KIR3DL2+ and HLA-A3/11+ plus high-affinity FCGR3A-158V allele showed the most prolonged PFS (HR=0.35; p=0.007). Consistent with these clinical data, mechanistic experiments demonstrated that NK cells expressing KIR3DL2 trigger greater ADCC when MM cells express HLA-A3/11. Inversely, NK cells expressing KIR2DL1 do not kill if MM cells express the HLA-C2C2 ligand. NK cells expressing high-affinity FCGR3A-158VV-induced greater ADCC compared with those with low-affinity FCGR3A-158FF.ConclusionsOur results suggest that KIR3DL2+ and HLA-A3/11+ with FCGR3A-158V markers lead to enhanced Isa-dependent NK-mediated cytolysis against MM cells and results in improved PFS in patients with RRMM treated by Isa-Len-Dex. Moreover, the presence of KIR2DL1+ and HLA-C2C2+ identifies patients who may have a lower response to Isa-Len-Dex therapy linked to a reduced NK-mediated ADCC. These biomarkers could potentially identify, via precision medicine, patients more likely to respond to Isa-Len-Dex immunotherapy.Trial registration numberNCT01749969.

BackgroundGraft-versus-host disease (GVHD) is a complication of allogeneic hematopoietic stem cell transplantation (HSCT). Transplacental maternal engraftment (TME), the presence of maternal T cells in peripheral blood before transplantation, is detectable in a significant proportion of patients with severe combined immunodeficiency (SCID). Although the presence of TME is associated with a decreased risk of rejecting a maternal graft, it is unknown whether TME plays a role in development of GVHD after HSCT.ObjectiveThe purpose of this study was to determine whether the presence of pretransplantation TME is associated with posttransplantation GVHD in patients with SCID.MethodsThis was an institutional retrospective review of 74 patients with SCID undergoing transplantation between 1988 and 2014. The incidence of acute graft-versus-host disease (aGVHD) was compared in patients with versus those without TME. Confounding variables, such as donor type and conditioning regimen, were included in a multivariate regression model.ResultsTME was identified in 35 of 74 children. Post-HSCT aGVHD developed with an incidence of 57.1% versus 17.9% in those without TME (P

The presence of increasing host chimerism or persistent mixed chimerism (MC) after hematopoietic stem cell transplantation for leukemia in children is a predictor of relapse. To reduce the risk of relapse, we prospectively studied post-transplantation chimerism-based immunotherapy (IT) using fast withdrawal of immunosuppression (FWI) and donor lymphocyte infusions (DLI) in children with early post-transplantation MC. Forty-three children with hematologic malignancies at 2 institutions were enrolled prospectively in this study from 2009 until 2012 and were followed for a mean of 42 (SD, 10) months. Twelve patients (28%) were assigned to the observation arm based on the presence of graft-versus-host disease (GVHD) or full donor chimerism (FDC), and 5 (12%) sustained early events and could not undergo intervention. Twenty-six (60%) patients with MC were assigned to IT with FWI, which started at a median of 49 days (range, 35 to 85 days) after transplantation. Fourteen patients proceeded to DLI after FWI. Toxicities of treatment included GVHD, which developed in 19% of patients undergoing intervention, with 1 of 26 (4%) dying from GVHD and 1 (4%) still requiring therapy for chronic GVHD 21 months after DLI. Patients with MC undergoing IT had similar 2-year event-free survival (EFS) (73%; 95% confidence interval (CI), 55% to 91%) compared with patients who achieved FDC spontaneously (83%; 95% CI, 62% to 100%); however, because 50% of all relapses in the IT occurred later than 2 years after transplantation, the EFS declined to 55% (95% CI, 34% to 76%) at 42 (SD, 11) months. There were no late relapses in the observation group. EFS in the entire cohort was 58% (95% CI, 42% to 73%) at 42 (SD, 11) months after transplantation. Evidence of disease before transplantation remained a significant predictor of relapse, whereas development of chronic GVHD was protective against relapse.

Abstract Background Biliary atresia (BA) is a neonatal cholestatic disease of unknown etiology. It is the leading cause of liver transplantation in children. Many similarities exist between BA and graft versus host disease suggesting engraftment of maternal cells during gestation could result in immune responses that lead to BA. The aim of this study was to determine the presence and extent of maternal microchimerism (MM) in the livers of infants with BA. Methods Using fluorescent in situ hybridization (FISH), 11 male BA & 4 male neonatal hepatitis (NH) livers, which served as controls, were analyzed for X and Y-chromosomes. To further investigate MM in BA, 3 patients with BA, and their mothers, were HLA typed. Using immunohistochemical stains, the BA livers were examined for MM. Four additional BA livers underwent analysis by polymerase chain reaction (PCR) for evidence of MM. Results By FISH, 8 BA and 2 NH livers were interpretable. Seven of eight BA specimens showed evidence of MM. The number of maternal cells ranged from 2–4 maternal cells per biopsy slide. Neither NH specimen showed evidence of MM. In addition, immunohistochemical stains confirmed evidence of MM. Using PCR, a range of 1–142 copies of maternal DNA per 25,000 copies of patients DNA was found. Conclusions Maternal microchimerism is present in the livers of patients with BA and may contribute to the pathogenesis of BA.

Chimerism is the unique state when cells from genetically different individuals coexist. Chimerism testing allows measuring the donor and recipient immune cell subsets in recipient blood and bone marrow following stem cell transplantation. Chimerism testing is the standard diagnostic test for monitoring engraftment dynamics and early relapse prediction in the recipient following stem cell transplantation. Chimerism testing is also helpful to detect graft-versus-host disease following liver transplantation. Herein, we describe a step-by-step procedure of an in-house-developed method assessing chimerism levels using fragment length analysis of short tandem repeats., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Chimerism is an unusual state in which a person's body comprises cells from genetically different people. Chimerism testing allows monitoring for the relative proportion of recipient and donor-derived cell subsets in recipient blood and bone marrow. In the bone marrow transplant setting, chimerism testing is the standard diagnostic tool for early detection of graft rejection and the risk of malignant disease relapse. Chimerism testing enables the identification of patients with increased risk for recurrence of the underlying disease. Herein, we describe a step-by-step technical procedure of a novel, commercially available, next-generation sequencing-based chimerism testing method for use in the clinical laboratory., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)