Alteration of in vitro immunoglobulin secretion by amosite asbestos.

We investigated the in vitro effects of amosite asbestos on immunoglobulin (Ig) secretion by human peripheral blood mononuclear leukocytes (MNL). Concentrations of 100 to 300 micrograms/ml of amosite asbestos reduced the number of Ig-secreting cells recovered from 6-day cultures of unstimulated MNL or MNL stimulated with Epstein Barr virus. By contrast, the Ig secretory response to pokeweed mitogen was enhanced by 10 to 100 micrograms/ml concentrations of amosite asbestos; however, amosite asbestos no longer enhanced the response to pokeweed mitogen when MNL were first partially depleted of monocytes (to less than 2%) esterase-positive cells remaining). These results indicate that amosite asbestos has multiple effects on the cells involved in Ig secretion: 1) amosite asbestos inhibits unstimulated B cell function; 2) amosite asbestos inhibits the function of B cells stimulated with the direct B cell activator Epstein Barr virus; and 3) amosite asbestos may alter regulator monocyte function allowing enhanced Ig secretion in the presence of monocyte-dependent B cell triggers such as pokeweed mitogen.