DIFFERENTIAL EXPRESSION OF THE LFA-1 MOLECULE ON THE HUMAN PERIPHERAL-BLOOD MONONUCLEAR CELL SUBPOPULATIONS

The expression of leukocyte function associated antigen 1 (LFA-1) was studied on human peripheral blood mononuclear cells (PBMNC) by a double immunofluorescence method. Monoclonal antibodies IOT18 (recognizing the β chain, 95 kDa, CD18) and SPVL7 (recognizing the α chain, 180 kDa, CD11a) were used. These antibodies revealed the same heterogeneous distribution of the LFA-1 molecule among peripheral blood mononuclear cells. A bimodal profile characterized the lymphocytes, whereas the monocyte subpopulation presented a unimodal profile. NK cells, including CD16, CD8 dim, expressed the LFA-1 with a high density. B cells expressing the CD19 phenotype showed surface LFA-1 at a low level, whereas it appeared with an intermediate intensity on the T helpers/inducers (CD4 cells). Among the cytotoxic cells (CD8) and the immunoregulatory subpopulations associated with an immunosuppressive response (CD8 + CD11b +, CD8 + Cd11b - and CD8 + leu8 +) or with a contrasuppressive response (Vicia villosa cells), an heterogeneous LFA-1 expression was observed, discriminating the LFA-1 dim and the LFA-1 bright cells. Anti LFA-1 antibodies also allowed us to define three novel subsets among the CD8 cells: the CD8 dim LFA-1 bright, the CD8 bright LFA-1 bright, and the CD8 bright LFA-1 dim cell subpopulations. This heterogeneous distribution of LFA-1 among PBMNC may be associated with different functions of the different cell subsets analyzed in this study. © 1990.