Proof-of-Principle for Immune Control of Global HIV-1 Reactivation In Vivo.

BACKGROUND: Emerging data relating to human immunodeficiency virus type 1 (HIV-1) cure suggest that vaccination to stimulate the host immune response, particularly cytotoxic cells, may be critical to clearing of reactivated HIV-1-infected cells. However, evidence for this approach in humans is lacking, and parameters required for a vaccine are unknown because opportunities to study HIV-1 reactivation are rare. METHODS: We present observations from a HIV-1 elite controller, not treated with combination antiretroviral therapy, who experienced viral reactivation following treatment for myeloma with melphalan and autologous stem cell transplantation. Mathematical modeling was performed using a standard viral dynamic model. Enzyme-linked immunospot, intracellular cytokine staining, and tetramer staining were performed on peripheral blood mononuclear cells; in vitro CD8 T-cell-mediated control of virion production by autologous CD4 T cells was quantified; and neutralizing antibody titers were measured. RESULTS: Viral rebound was measured at 28,000 copies/mL on day 13 post-transplant before rapid decay to <50 copies/mL in 2 distinct phases with t1/2 of 0.71 days and 4.1 days. These kinetics were consistent with an expansion of cytotoxic effector cells and killing of productively infected CD4 T cells. Following transplantation, innate immune cells, including natural killer cells, recovered with virus rebound. However, most striking was the expansion of highly functional HIV-1-specific cytotoxic CD8 T cells, at numbers consistent with those applied in modeling, as virus control was regained. CONCLUSIONS: These observations provide evidence that the human immune response is capable of controlling coordinated global HIV-1 reactivation, remarkably with potency equivalent to combination antiretroviral therapy. These data will inform design of vaccines for use in HIV-1 curative interventions.

Interactions of NK cell receptor KIR3DL1*004 with chaperones and conformation-specific antibody reveal a functional folded state as well as predominant intracellular retention.

Variable interaction between the Bw4 epitope of HLA-B and the polymorphic KIR3DL1/S1 system of inhibitory and activating NK cell receptors diversifies the development, repertoire formation, and response of human NK cells. KIR3DL1*004, a common KIR3DL1 allotype, in combination with Bw4(+) HLA-B, slows progression of HIV infection to AIDS. Analysis in this study of KIR3DL1*004 membrane traffic in NK cells shows this allotype is largely misfolded but stably retained in the endoplasmic reticulum, where it binds to the chaperone calreticulin and does not induce the unfolded protein response. A small fraction of KIR3DL1*004 folds correctly and leaves the endoplasmic reticulum to be expressed on the surface of primary NK and transfected NKL cells, in a form that can be triggered to inhibit NK cell activation and secretion of IFN-γ. Consistent with this small proportion of correctly folded molecules, trace amounts of MHC class I coimmunoprecipitated with KIR3DL1*004. There was no indication of any extensive intracellular interaction between unfolded KIR3DL1*004 and cognate Bw4(+) HLA-B. A similarly limited interaction of Bw4 with KIR3DL1*002, when both were expressed by the same cell, was observed despite the efficient folding of KIR3DL1*002 and its abundance on the NK cell surface. Several positions of polymorphism modulate KIR3DL1 abundance at the cell surface, differences that do not necessarily correlate with the potency of allotype function. In this context, our results suggest the possibility that the effect of Bw4(+) HLA-B and KIR3DL1*004 in slowing progression to AIDS is mediated by interaction of Bw4(+) HLA-B with the small fraction of cell surface KIR3DL1*004.

Presence of donor-encoded centromeric KIR B content increases the risk of infectious mortality in recipients of myeloablative, T-cell deplete, HLA-matched HCT to treat AML.

The reported influence of donor Killer-cell Immunoglobulin-like Receptor (KIR) genes on the outcomes of haematopoietic cell transplantation (HCT) are contradictory, in part due to diversity of disease, donor sources, era and conditioning regimens within and between different studies. Here, we describe the results of a retrospective clinical analysis establishing the effect of donor KIR motifs on the outcomes of 119 HLA-matched, unrelated donor HCT for adult acute myeloid leukaemia (AML) using myeloablative conditioning (MAC) in a predominantly T-cell deplete (TCD) cohort. We observed that HCT involving donors with at least one KIR B haplotype were more likely to result in non-relapse mortality (NRM) than HCT involving donors with two KIR A haplotypes (p = 0.019). Upon separation of KIR haplotypes into their centromeric (Cen) and telomeric (Tel) motif structures, we demonstrated that the Cen-B motif was largely responsible for this effect (p = 0.001). When the cause of NRM was investigated further, infection was the dominant cause of death (p = 0.006). No evidence correlating donor KIR B haplotype with relapse risk was observed. The results from this analysis confirm previous findings in the unrelated, TCD, MAC transplant setting and imply a protective role for donor-encoded Cen-A motifs against infection in allogeneic HCT recipients.

The elucidation of KIR2DL4 gene polymorphism.

The killer cell immunoglobulin-like receptors (KIRs) on NK cells recognize defined groups of HLA class I alleles. By this mechanism the NK cells fulfil a significant role in the first line of defense against infectious agents and cancer. For the treatment of leukaemia this NK cell allorecognition is of great importance. Still, an appropriate effect against the leukaemic cells requires sufficient expression of both KIR and HLA proteins. KIR gene polymorphism influence membrane expression of the KIR protein. We addressed KIR2DL4 gene polymorphism by a newly developed DNA and cDNA based direct sequencing based typing (SBT) and cloning approach. A panel of 44 individuals revealed a variety of KIR2DL4 alleles. Three new alleles have been identified, among those one allele showed alternatively spliced products. In conclusion, this approach is applicable for routine KIR2DL4 allele typing and enables the characterisation of new KIR2DL4 alleles.

Activating KIRs exert a crucial role on relapse and overall survival after HLA-identical sibling transplantation.

Recognition of HLA-C molecules by killer cell immunoglobulin-like receptors (KIRs) is an important mechanism in the regulation of natural killer (NK) cell activity. Eradication of residual leukaemic cells by alloreactive donor NK cells after haematopoietic stem cell transplantation (HSCT) fulfils a crucial role in the control of relapse. This retrospective study evaluates 83 patients and their related donors. All individuals were typed at low-resolution level to determine their HLA repertoire. KIR genotyping data were obtained by the use of sequence-specific oligonucleotide (SSO) analysis. All data were combined with patient and donor characteristics and post-transplant clinical data. A higher overall survival was seen when KIR2DS1 in the donor was mismatched with the HLA-C group 2 ligand in the patient (p=0.03). The number of activating KIRs either in the patient or in the donor was significantly correlated with the occurrence of relapse (p=0.003 and p=0.02, respectively). In addition, the presence of KIR2DS5 in the patient alone or in both the patient and donor was significantly correlated with the occurrence of relapse (p=0.004 and p=0.005, respectively). In conclusion, significant correlations were found for activating KIRs with overall survival and relapse.

Patients benefit from the addition of KIR repertoire data to the donor selection procedure for unrelated haematopoietic stem cell transplantation.

Killer cell immunoglobulin-like receptors (KIRs) expressed on donor natural killer (NK) cells are important for induction of NK cell alloreactivity in haematopoietic stem cell transplantation (HSCT). Current criteria in the selection procedure of an unrelated donor do not account for this potential NK alloresponse. In this study the KIR gene repertoire of 21 HSCT patients and all their potential, unrelated donors (N=64) has been identified by the sequence-specific priming (SSP) procedure. KIR genotype characteristics are correlated with HLA and clinical data. These data show that for 16 cases an HLA compatible alternative donor was available. Among those 16 were 8 donors with a favourable predicted NK alloreactivity directed against the leukaemic cells. In conclusion, it is feasible and clinically relevant to add the KIR repertoire to the unrelated donor selection procedure.

Natural killer cells and killer-cell immunoglobulin-like receptor polymorphisms: their role in hematopoietic stem cell transplantation.

Natural killer (NK) cells are important effector cells in the early control of infected, malignant, and "nonself" cells. Various receptor families are involved in enabling NK cells to detect and efficiently eliminate these target cells. The killer-cell immunoglobulin-like receptor (KIR) family is a set of receptors that are very polymorphic with regard to gene content, expression level, and expression pattern. KIRs are responsible for the induction of a NK cell alloreactive response through their interaction with HLA class I molecules. The role of NK cells in hematopoietic stem cell transplantation (HSCT) has been studied for many years, and induction of antileukemic responses by donor NK cells has been reported. Conflicting data still exist on the exact circumstances in which the KIR repertoire affects and influences clinical outcome after HSCT. More large-scale studies are needed on well-defined cohorts to unravel the mechanism of action of the NK cell-mediated alloresponse in an HSCT setting.

The killer immunoglobulin-like receptor (KIR) group A haplotype is associated with bronchiolitis obliterans syndrome after lung transplantation.

BACKGROUND: The development of bronchiolitis obliterans syndrome (BOS) after lung transplantation is associated with viral infections. Natural killer (NK) cells are involved in the lysis of viral infected cells, and their activation is largely controlled by activating and inhibitory killer immunoglobulin-like receptors (KIRs). We hypothesized that KIR ligand incompatibility and recipients' individual KIRs could influence the development of BOS and the incidence of cytomegalovirus reactivation after lung transplantation. METHODS: The KIR gene contents were determined in 48 patients who received a lung transplant, and human leukocyte antigen (HLA)-Cw and HLA-Bw4 typing was performed on their respective donors. RESULTS: BOS developed in 7 patients and cytomegalovirus reactivation occurred in 16. BOS developed in 5 of 19 patients homozygous for KIR haplotype A compared with 2 of 27 patients with KIR haplotype AB and B (homozygous; p = 0.03; log-rank test). In none of the patients with BOS was the activating KIR2DS5 gene detected, whereas it was present in 35% of patients without BOS (p = 0.04; log-rank test). No correlation was found between KIR gene content and cytomegalovirus reactivation. CONCLUSION: Our results suggest that the lack of activating KIRs may play an important role in the development of BOS but not in the control of cytomegalovirus reactivation after lung transplantation.