Mononuclear cell subpopulations in the skin defined by monoclonal antibodies after HLA-identical sibling marrow transplantation

Mononuclear cell subpopulations present in the skin of 36 recipients of HLA-identical sibling marrow transplants were defined by immunoperoxidase using a battery of monoclonal antibodies to cell surface differentiation antigens. The T4-positive (T4+) (helper-inducer T cells), T8+ (cytotoxic-suppressor T cells) and the T6+ (Langerhans cells) decreased in number early post transplant and returned towards normal numbers from day 42 onwards. There was no evidence that either the T4+ or the T8+ subset was involved in cell-to-cell contact damage in acute graft-versus-host disease (GVHD). The paucity of lymphoid cell infiltration of the epidermis in acute GVHD suggested the possibility of a soluble factor being responsible for basal layer damage. In patients with chronic GVHD there was no evidence of T4+ lymphocyte involvement, but T8+ lymphocytes were present in increased numbers, suggesting a role for the T8+ population in the skin lesions of chronic GVHD, or possibly a reflection of the pattern of T4+ and T8+ cell reconstitution in the blood post-transplant. Finally, our study provided no evidence that BI+ (B cells), Leu 7+ (natural killer cells), OKMI+ (histiocytes) or OKT1O+ cells were involved in cell-to-cell contact damage in either acute or chronic GVHD.