THE LYMPHOCYTIC INFILTRATE IN ACUTE CUTANEOUS ALLOGENEIC GRAFT-VERSUS-HOST REACTIONS LACKS EVIDENCE FOR PHENOTYPIC RESTRICTION IN DONOR-DERIVED CELLS

The lymphocytic subtypes effecting allogeneic graft-versus-host diseas e (GVHD) are unknown. We studied 35 skin biopsy specimens from 19 wome n transplanted with bone marrow from men for patterns and time course of infiltration of the skin by Y chromosome-bearing lymphocytes using in situ hybridization. Immunophenotypic analysis was performed on seri al sections. Significant numbers of donor cells were first observed by day 13 after bone marrow transplantation (BMT), although a few cells were noted at earlier time points. The quantity of donor lymphocytes i n the dermis correlated with the diagnosis of GVHD. For specimens with grade 1 features, only rare cells bore the Y chromosome, whereas the majority of lymphocytes in grade 2 tissues, whether heavily inflamed o r not, contained the Y chromosome. These lymphocytes were predominantl y CD4+ with fewer CD8+ and CD56+ cells in the dermis and epidermis. No concentration of a specific subtype in the epidermal compartment was observed. These data do not support the observation that a cutaneous g raft-versus-host reaction (GVHR) is mediated primarily by CD8+ lymphoc ytes. Several effector cell populations may mediate a cutaneous GVHR w ith further variation over time and in BMTs between different individu als. (C) Munksgaard 1998.