HUMAN CD4+CD45RA+LYMPHOCYTES-T CAN BE STIMULATED BY CROCIDOLITE, ANTHOPHYLLITE AND AMOSITE ASBESTOS INVITRO

Crocidolite, anthophyllite and amosite asbestos stimulate T lymphocyte subsets. Cell surface CD4 or CD45RA expression in peripheral blood mononuclear cells (PBMC) was downregulated temporarily after incubation with asbestos in vitro. The percentage of CD4+ CD45RA+ cells significantly decreased 12 h after incubation with asbestos, suggesting activation of the cells. An early increase in the intracellular Ca++ level was also indicative of activation. An elevated Ca++ level was observed after incubation in both PBMC and purified T cell fractions.