Asbestos-induced Alterations of Human Lymphoid Cell Mitogenic Responses

Using mitogenic assays, we have investigated the short term effects of two asbestos (amosite and chrysotile) fibers on lymphocyte functions in vitro. These oppositely charged fibers produced different alterations in mitogenesis. The blastogenic responses of concanavalin-A (Con-A) and pokeweed mitogen stimulated human peripheral blood mononuclear cells (PBMN) were significantly increased by the inclusion of 6 micrograms of chrysotile to the culture media. Amosite fibers proved to be inhibitory in all tests. When PBMN were depleted of monocytes, asbestos-related alterations of Con-A responsiveness were unchanged among the remaining cells. However, the addition of chrysotile to phytohemagglutinin (PHA) cultures resulted in a significant increase of the mitogenic response. When PBMN were enriched for T lymphocytes, and again cultured with the mitogens and fibers, the Con-A response still displayed impressive enhancement with chrysotile. In contrast to an intact PBMN population, PHA-induced blastogenesis among these T-enriched lymphocytes was significantly elevated. These experiments demonstrate that asbestos can induce significant changes in the functional integrity of PBMN following a relatively short exposure time in culture.