Analysis of KIR2D receptors on peripheral blood lymphocytes from liver graft recipients

KIR2D receptors are killer cell immunoglobulin-like receptors (KIRs) specific for HLA-C epitopes, that are expressed on NK cells as well as on minor peripheral blood T-cell subsets, and are able to control NK and T cells activity. The present work explores NK, and particularly CD8+ T cells expressing KIR2D2L1/S1 (CD158a) or KIR2D2L2/3/S2 (CD158b) receptors in liver graft alloresponse. Flow cytometry was used to analyse peripheral blood mononuclear cells stained with anti-CD158a and anti-CD158b antibodies from 110 liver recipients and 46 healthy controls, previous to and along the first month after transplantation. Pre-transplantation data shows that both CD158a and CD158b molecules can be detected on NK and T cells from all patients and controls, but both KIR2D+NK cells are significantly under-represented in patients respect to controls (P < 0.001), and CD3+CD8+CD158a+ cells decreased particularly in patients suffering from acute rejection (4.03 ± 1.33 cells/μL) compared with controls (7.8 ± 2.4 cells/μL). Following transplantation, KIR2D+CD8+ T-cell repertoires increased through the first month, mainly in recipients with a good graft acceptance. In summary, monitoring of KIR2D+CD8+ T cells, particularly KIR2DL1/S1+CD8+ T cells at pre-transplant, and both KIR2DL1/S1+ and KIR2DL2/3/S2+ T-cell subsets at early post-transplant period, could offer useful information for clinical follow-up of liver grafts.