Activation-induced cell death in human peripheral blood lymphocytes after stimulation with silicate in vitro.
- T Aikoh
- A Tomokuni
- T Matsukii
- F Hyodoh
- H Ueki
- T Otsuki
- A Ueki
Affiliations: Department of Hygiene, Kawasaki Medical School, Kurashiki 701-01, Japan.
- Published online on: June 1, 1998 https://doi.org/10.3892/ijo.12.6.1355
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Silica and related substances such as silicate have been proven to possess "adjuvant effects". We have previously reported a finding of polyclonal human T cell activation induced by silicate as a superantigen in vitro. In this study, we observed activation-induced cell death in human lymphocytes after stimulation with chrysotile, a kind of silicate. Apoptotic cells were detected flow cytometrically using the TUNEL assay, and the maximum appearance of TUNEL positive cells occurred on day 4 of incubation. Simultaneously the manifestation of small-sized cells in the specimens increased implying apoptosis. Fas expression on lymphocytes increased to day 3 of incubation with chrysotile, and then spontaneously decreased on day 4 when remarkable apoptosis could be detected. Based on these results it is conceivable that activation-induced cell death occurred through Fas-Fas ligand interaction in lymphocytes after stimulation with silicate in a concentration with which no acute cytotoxicity has been detected. Whether and how the repeated apoptosis in definite clones of lymphocytes causes the induction of sFas synthesis need clarification.