Effects of in vitro asbestos exposure on natural killer and antibody-dependent cellular cytotoxicity

Human peripheral blood lymphocytes (PBL) were exposed in vitro to asbestos fibers. Antibody-dependent cellular cytotoxicity (ADCC) activity and natural killer (NK) activity were examined by a chromium-51 release assay. There was a statistically significant enhancement of ADCC and NK activity by chrysotile and crocidolite fibers when cultured together with PBL for a period of 42 hr in medium containing a concentration of at least 2.5% fetal calf serum (P less than 0.05). Isolation of large granular lymphocytes to measure NK activity, however, showed the opposite effect when exposed to asbestos fibers (P less than 0.05). Our results indicate that asbestos fibers can directly affect lymphoid cytotoxic responses in vitro and may provide clues to immunopathogenic mechanisms for the occurrence of neoplasms in vivo.