In vitro effects of triphenyltin acetate (TPTA) on mouse lymphocyte proliferation

Organotin compounds (OTs) are used worldwide in industry and in agricultural practice. In Italy, the OT mostly used is the fungicide triphenyltin acetate (TPTA), although in past years it has been submitted to revision for occupational and environmental grounds. In the present study, the possible effect of the fungicide on cell proliferation has been investigated, using [(3)H]thymidine incorporation radiometric assay. Mouse thymocytes in primary culture were stimulated for 24 h with T- and B-cell mitogens (concanavalin A, CON A and phytohemagglutinin, PHA or pokeweed mitogen, PWM, respectively). Cultures were then exposed 24 h to 0, 1 and 8 microM TPTA. At the end of incubation, cells were pulsed with methyl-[(3)H]thymidine and harvested for total radioactivity counts after a further 24 h of incubation. An overall dose-dependent significant (P<0.05) reduction of proliferative response was observed with all mitogens tested. Interestingly, CON A proved to be more sensitive (P<0.05) to the TPTA toxic effect compared with PWM and PHA. TPTA is cytotoxic to mouse thymocytes in primary culture, particularly towards the mature lymphocytes (CD4(+) and CD8(+)). The present results support the hypothesis of a TPTA-induced decrease of lymphoproliferative response to T- and B-cell mitogens, previously observed with other OTs.