Effect of dithiocarbamate pesticide zineb and its commercial formulation, azzurro. II. micronucleus induction in immunophenotyped human lymphocytes.

The frequency of micronuclei was measured in human peripheral B-lymphocytes and some T-lymphocyte subpopulations exposed in vitro to 1.0-100.0 microg/ml of the dithiocarbamate pesticide zineb and its commercial formulation azzurro. The peripheral mononuclear lymphocytes were stimulated in vitro with phytohemagglutinin after pesticide treatment and B-lymphocytes and the various T-lymphocyte subsets were classified by the MAC (morphology, antibody, chromosomes) method, which allows the immunological identification of different cell lineages. An increased frequency of micronuclei in CD20(+) (P < 0.01), CD3(+) (P < 0.01), and CD8(+) lymphocytes (P < 0.01) was observed only when 25.0 microg/ml of zineb and azzurro were employed. The frequency of micronuclei in treated CD8(+) cells did not differ from treated CD20(+) lymphocytes (P > 0.05). Lower concentrations of pesticides did not increase the frequency of micronuclei from that observed in control cultures. Furthermore, for both zineb and azzurro cytotoxicity was observed at doses higher than 50.0 microg/ml. Significant increases in the proportion of CD20(+) (P < 0.01) and CD8(+) cells (P < 0.01) among mitotic and interphasic lymphocytes from both zineb- and azzurro-treated cultures were observed only when a concentration of 25.0 microg/ml was employed. In contrast, significant decreases in the proportion of CD3(+) (P < 0.01) and CD4(+) cells (P < 0.01) were found for both mitotic and interphasic lymphocytes from zineb- and azzurro-treated cultures. The MAC methodology revealed that among the different lymphocyte subpopulations analyzed (CD20, CD3, CD4, and CD8), the induction of micronuclei by zineb and its commercial formulation azzurro was restricted to CD20(+) B-cells and T-suppressor/cytotoxic CD8(+) lymphocytes. Copyright 2002 Wiley-Liss, Inc.