The genetic predisposition of natural killer cell to BK virus-associated nephropathy in renal transplant patients.

BK virus (BKV) infection represents a serious complication in renal transplant patients resulting in BKV-associated nephropathy and subsequent allograft loss. Natural killer cells are crucial in the antiviral immune response; however, an understanding of the role of natural killer cells in protection against BKV is limited. To elucidate whether killer-cell immunoglobulin-like receptors and their interaction between donor-/recipient-related ligands have a role in BKV infection, we performed genotyping analysis in 48 kidney transplant recipients with a history of severe BKV infection/BKV-associated nephropathy and 110 recipients with stable renal function and no BKV reactivation. Of interest, we found that telomeric gene content motif was significantly associated with severe course of BKV infection/BKV-associated nephropathy and detected significantly higher percentage of patients with BKV-associated nephropathy carrying low numbers of activating receptors compared with the control group. Detailed analysis of each single receptor revealed significantly lower frequencies of the activating receptor KIR3DS1 in patients with BKV infection/nephropathy as compared with the controls. Thus, our study supports protective effects of activating receptors in BKV infection and suggest natural killer-cell-related genetic predisposition to the development of BKV-associated nephropathy.

Novel markers in zero-hour kidney biopsies indicate graft quality and clinical outcome.

BACKGROUND: In renal transplantation, allograft biopsies provide valuable diagnostic information indicating adverse allograft outcome posttransplantation. To uncover novel candidate markers characteristic of subtle inflammation and immune activation present during the intraoperative period, we investigated messenger RNA (mRNA) gene expression profiles in renal zero biopsies. METHODS: Transcription profiles from deceased donors (n=63) and living donors (n=26) were investigated for inflammation-associated markers in zero-hour biopsies by real-time reverse-transcriptase polymerase chain reaction. RESULTS: We observed a significant induction of the chemokine receptor 7 ligands [C-C motif] ligand 19/21 in the deceased donor group (P<0.001). Additionally, along with the induction of the activation marker CD69 (P<0.01), we further detected significant elevated mRNA levels of the inducible immunoproteasome subunits PSMB8, PSMB9, and PSMB10 (P<0.001, respectively). Candidate markers were further tested for posttransplantation clinical outcomes showing the potential to predict the development of delayed graft function, acute rejection, and renal function after 6 months. For instance, by combining mRNA gene expression profiles with clinical patient data, the analysis revealed high sensitivity (95%) and specificity (84%, area under the curve=0.93) for the prediction of acute rejection. CONCLUSIONS: Zero-hour biopsies of renal allografts may provide useful information on subclinical pathological changes in the grafted kidney. The identification of CCL19/21 or PSMB8/9/10 makes these molecules particularly suitable as potential candidate targets for therapeutic interventions.

Targeting of natural killer cells by rabbit antithymocyte globulin and campath-1H: similar effects independent of specificity.

T cell depleting strategies are an integral part of immunosuppressive regimens widely used in the hematological and solid organ transplant setting. Although it is known to induce lymphocytopenia, little is known about the effects of the polyclonal rabbit antithymocyte globulin (rATG) or the monoclonal anti-CD52 antibody alemtuzumab on Natural Killer (NK) cells in detail. Here, we demonstrate that induction therapy with rATG following kidney/pancreas transplantation results in a rapid depletion of NK cells. Treatment of NK cells with rATG and alemtuzumab in vitro leads to impairment of cytotoxicity and induction of apoptosis even at a 10-fold lower concentration (0.1 microg/ml) compared with T and B cells. By generating Fc-parts of rATG and alemtuzumab we illustrate that their ligation to FcgammaRIII (CD16) is sufficient for the significant induction of degranulation, apoptosis and inflammatory cytokine release (FasL, TNFalpha and IFNgamma) exclusively in CD3(-)CD56(dim) NK cells whereas application of rATG and alemtuzumab F(ab) fragments abolishes these effects. These findings are of general importance as our data suggest that NK cells are also mediators of the clinically relevant cytokine release syndrome and that their targeting by therapeutic antibodies should be considered as they are functionally relevant for the effective clearance of opportunistic viral infections and anti-tumor activity posttransplantation.

KIR/HLA ligand incompatibility in kidney transplantation.

BACKGROUND: The polymorphic family of killer-cell immunoglobulin-like receptors (KIRs) consists of activating and inhibitory receptors expressed by natural killer (NK) cells and effector T cells that recognize human leukocyte antigen (HLA) class I ligands. It has been suggested that KIR/HLA incompatibility exerts beneficial effects in hematopoietic stem cell transplantation. METHODS: To elucidate whether certain receptor-ligand combinations between recipient KIR and donor HLA antigens lead to enhanced alloreactivity of NK cells associated with acute rejection (aRx) after kidney transplantation, we analyzed the entirety of matches/mismatches between KIR genes and known HLA ligands for aRx patients (n=105) compared to patients with stable renal function (n=119). RESULTS: Whereas HLA-C ligand incompatibility between donor and recipient has no influence on aRx, grafts derived from donors homozygous for HLA-C group 2 alleles seem to demonstrate a better outcome (P=0.052). Additionally, a higher number of inhibitory receptors in the recipient's genotype (P=0.042), a significant higher number of matches for the receptors KIR2DL2/DS2 (P=0.004), as well as a higher number of mismatches for KIR2DL3 (P=0.014) could be observed for patients with stable renal function. CONCLUSION: Our data illustrate that certain KIR/HLA class I ligand combinations between donor and recipient might influence graft short-term outcome after renal transplantation.