The Suppressed Induction of Human Mature Cytotoxic T Lymphocytes Caused by Asbestos Is Not due to Interleukin-2 Insufficiency

We previously reported that exposure to chrysotile b (cb) asbestos suppressed the induction of mature cytotoxic t lymphocytes (ctls) during mixed lymphocyte reaction assays (mlrs) with a decrease in the proliferation of immature ctls. however,the mechanism responsible for the effect of asbestos fibers on the differentiation of ctls remains unclear. since interleukin-2 (il-2) is a regulator of t lymphocyte proliferation,we examined the effect of il-2 addition on suppressed ctl differentiation in cb-exposed cultures using flow cytometry (fcm). when il-2 was added at 1 ng/ml on the second day of mlrs,the asbestos-caused decreases in the proliferation and percentages of cd25+ and cd45ro+ cells in cd8+ lymphocytes were not recovered by il-2 addition,although the decrease in percentage of granzyme b+ cells was partially recovered. cd8+ lymphocytes from the il-2-treated culture with asbestos showed the same degree of cytotoxicity as those in cultures without il-2 or asbestos. these findings indicate that il-2 insufficiency is not the main cause for the suppressed induction of ctls by asbestos exposure,although they suggest a potential for the improvement of such suppressed ctl functions. secretory factors other than il-2 in addition to membrane-bound stimulatory molecules may play a role in asbestos-caused suppressed ctl differentiation. � 2016 naoko kumagai-takei et al.