Phenotype and function of T lymphocytes infiltrating the skin during graft-versus-host disease following allogeneic bone marrow transplantation

Seven lymphocyte populations were expanded from skin samples of patients with acute or chronic GVHD following allogeneic genotypically identical BMT. After amplification without in vitro antigenic stimulation or addition of mitogens, 5 of the 7 cell lines showed a large majority of mature CD4⁺ T cells (in contrast to published immunopathological data). One cell line showed an equal number of CD4⁺ and CD8⁺ cells, and another a predominance of CD4⁺ cells along with a large number of cells with a phenotype suggestive of non—MHC-restricted CTLs. After in vitro antigenic stimulation, various cytotoxicity patterns were seen: specific antihost cytotoxicity was seen in half the cell lines, NK activity was seen in 5 of the 7 lines, and a strong LAK activity was seen in 1 of the 7 cell lines. These results point to a diversity of cytotoxic effectors involved locally in GVHD and emphasize the need for further study of these local events. The cell lines established now constitute basic functional material for the in vitro study of cellular and humoral interactions at the site of GVHD lesions.