DETECTION OF INTRACELLULAR LIPOCORTIN-1 IN HUMAN-LEUKOCYTE SUBSETS

Lipocortin 1, a putative mediator of the antiinflammatory actions of g lucocorticoids, is present intracellularly in a variety of tissues inc luding human peripheral blood leukocytes. We investigated the presence of lipocortin 1 in human leukocyte subsets using permeabilization flo w cytometry. Constitutive lipocortin 1 was detected in U937 myelomonoc ytic leukemia cells, and lipocortin 1 was increased by treatment with PMA or PMA + IFN-gamma (P < 0.05) but not by dexamethasone. Lipocortin 1 was present in all leukocyte subsets except B lymphocytes (CD19/20( +), P < 0.001). Lipocortin 1 content was maximal in monocytes and poly morphonuclear neutrophils and least in lymphocytes (P < 0.001). Monocy te lipocortin 1 was strongly associated with surface expression of CD1 4 and HLA-DR. Among non-B lymphocytes, a range of lipocortin 1 fluores cence was observed. Lipocortin 1 fluorescence was greatest in natural killer cells (CD56+, P < 0.001) and CD57(+) cells, but T cell subset m arkers did not otherwise discriminate variations in lipocortin 1. Indu ction of lymphocyte proliferation by PHA, anti-CD3, Con A, superantige n, and SAC was not associated with significant shifts in lipocortin 1 content. Dexamethasone (10(-10)-10(-6) M) did not induce increases in PB leukocyte lipocortin 1. We conclude that lipocortin 1 content in hu man leukocytes varies significantly among phenotypic subsets. This has significance for the investigation of inflammatory disease where cert ain cell types predominate. (C) 1995 academic Press, Inc.