Inhibition of platelet function by GSTM1-null human peripheral lymphocytes exposed to benzo(a)pyrene-induced challenge

Recent epidemiological studies proposed that the glutathione S-transferase (GST) M1-null genotype may contribute to diseases associated with oxidative stress. The genetic polymorphism exhibited by theGSTM1 may be an important factor in risk toward oxidant chemicals. In this study, we investigated the effect ofGSTM1-null genotype in lymphocyte and oxidative stress-dependent inhibition of platelet aggregation. To determine whether GSTM1 deficiency is a genetic determinant of cell toxicity toward oxidant chemicals, lymphocytes were incubatedin vitro with low levels of benzo(a)pyrene (BaP), cumene hydroperoxide (CumOOH), ortrans-stilbene oxide that do not decrease cell viability, and were assessed for oxidative damage and for the lymphocyte-dependent inhibition of platelet response. Malondialdehyde and carbonyl levels, and the oxidation ofcis-parinaric acid, were used as biomarkers of oxidative stress in lymphocytes. Following stimulation by BaP or CumOOH, when peroxidation-dependent changes in these parameters were compared between theGSTM1-null genotype and the positive genotype, no significant differences were found between the two genotypes. On the other hand, preincubation of the lymphocytes with BaP or CumOOH attenuated their inhibitory action on ADP-induced platelet aggregation. However, our results indicate that lymphocytes of individuals with theGSTM1-null genotype have greater inhibitory activity on platelet function after exposure to BaP, but not CumOOH, although they are not more susceptible toin vitro oxidative stress. This revised version was published online in July 2006 with corrections to the Cover Date.