Difference in the expression of Fas/Fas-ligand and the lymphocyte subset reconstitution according to the occurrence of acute GVHD

Acute graft-versus-host disease (aGVHD) remains a major barrier to a wider application of allogeneic bone marrow transplantation (BMT), Although this complication is mainly dependent on donor-derived T lymphocytes, very little information is available concerning the mechanism of lethality, In this study, we investigated both the expression of Fas/Fas-ligand (FasL) and lymphocyte subset reconstitution in patients who underwent HLA-matched related allogeneic BMT (n = 16) and normal donors (n = 10), and several distinct features were observed, First, the reconstitutions of CD3(+) and CD56(+) cells were different between the aGVHD(+) and aGVHD(-) group, In particular, the percentage of CD3(-)CD56(+) cells was significantly decreased in patients with aGVHD (P < 0.01), Second, the expansion of CD8(+) (P = 0.01) and CD8(+) CD28(-) T cells (P = 0.03) was a characteristic finding in patients with aGVHD, Finally, we found that the percentages of Fas(+)CD8(+), Fas(+)HLA-DR+ and FasL(+) CD8(+) cells were significantly increased, Fas antigen was highly coexpressed on most of the lymphocyte subsets, especially on CD8(+) cells (P < 0.01), and also, significantly higher coexpression of Fast on CD8(+) cells was found in patients with aGVHD (P < 0.01), In summary, an increase in the percentage of CD8(+) cells which express Fas and its ligand in patients with aGVHD after BMT points to a possible role for the Fas/FasL pathway in the effector phase of aGVHD.