Expression of HLA-C-specific natural killer cell receptors (CD158a and CD158b) on peripheral blood mononuclear cells after allogeneic bone marrow transplantation

Abstract

We investigated the expression of natural killer cell receptors (NKRs) for HLA-C on peripheral blood mononuclear cells (PBMCs) in 23 allogeneic bone marrow transplantation (allo-BMT) patients to analyse the role of NKRs in alloresponse concerning graft-versus-host disease (GVHD). CD158a expression was low and there was little change in the expression after allo-BMT. Also, there was no difference in the proportion of CD158a+/CD3- after allo-BMT. In contrast, the proportion of CD158b+/CD3- cells, mainly NK cells, increased in the early stage (< 2 months) after allo-BMT and then gradually decreased (3.3 ± 2.6% before BMT vs. 15.4 ± 8.6% in the early stage after BMT, 8.5 ± 4.9% during the period 3-6 months after BMT and 7.0 ± 3.0% >6 months after BMT; P< 0.05). However, CD158b expression on CD3+ T cells increased 3 months after allo-BMT (1.1 ± 1.1% before BMT vs. 5.1 ± 7.7% during the period 3-6 months after BMT and 3.0 ±2.4% > 6 months after BMT, P < 0.05). The highest percentages of CD158 expression in patients without chronic GVHD (cGVHD) and those with cGVHD were compared. The percentage of CD158b+/CD3+ cells and also that of CD158b+/CD8+ cells were significantly increased in patients with cGVHD compared with those in patients without cGVHD (2.6 ± 2.0% vs. 8.0 ± 11.2% and 2.3 ± 1.5% vs. 8.3 ± 11.7% respectively; P < 0.05). The exact clinical relevance of these CD158b- expressing cells is not clear. However, there is an interesting possibility that CD158b-expressing cells play some role in the regulation of GVHD after allo-BMT.