Preferential binding of monocytes and Leu 2+ T lymphocytes to interferon-gamma treated cultured skin endothelial cells and keratinocytes.

Recombinant gamma interferon (r-IFN-gamma) increases the adherence of peripheral blood mononuclear leukocytes (PBMLs) to cultured keratinocytes and cutaneous microvascular endothelial cells (MECs). To determine which specific type of PBMLs bound to these r-IFN-gamma treated cells, we performed immunophenotyping on the adherent PBMLs. The adherent PBMLs were detached from the r-IFN-gamma treated keratinocytes and MECs by adding EDTA, and collected by cytocentrifugation, followed by immunocytochemical staining using a panel of monoclonal antibodies. Our results reveal that the relative adherent population of PBMLs was composed of approximately 60%-70% monocytes and 18%-24% Leu 2+ T lymphocytes (T-cytotoxic/suppressor) which preferentially bound to r-IFN-gamma treated keratinocytes and MECs. There was some lesser binding by Leu 3 + lymphocytes (T-helper/inducer); approximately 8%, and no binding of B lymphocytes. Since r-IFN-gamma also induced HLA-DR expression in keratinocytes and MECs, these in vitro data suggest that r-IFN-gamma may play an important role in the immunobiology of diverse skin diseases such as graft vs host disease, lichen planus, and other inflammatory dermatoses, because the keratinocytes express HLA-DR and the predominant T-cell subset in the epidermis is Leu 2 + (over the Leu 3 + T cell) in all of these conditions. These results represent a direct attempt to explain in situ immunophenotypic mononuclear leukocyte subset distribution patterns by using r-IFN-gamma and purified cultured cells such as keratinocytes and MECs. We propose that IFN-gamma, by both increasing the adherence of PBMLs, and promoting selective binding of monocytes and Leu 2 + T lymphocytes to both keratinocytes and MECs, may be important in regulating PBML localization and recirculation in the skin.