Transplacental effects of IgG generated against soluble 53 kDa protein on the splenic lymph system of rat progeny exposed to carcinogen: rate of apoptosis, proliferation of lymphocytes and expression of Fas and Fas ligand proteins

Background. We have previously shown that vaccination with IgG generated ag ainst the soluble 53 kDa (s53) protein modified the splenic response to car cinogens. Here we studied whether such immunization could affect the spleni c lymphatic system of the offspring. Methods. Offspring of normal female rats or of rats immunized with anti-s53 IgG were exposed to a carcinogen (dimethyl-benz(a)antracene). After 4 mont hs, their spleens were resected and evaluated immunohistochemically for lym phocyte proliferation, apoptosis and apoptosis-related proteins (Fas and Fa s ligand), in tumor-free and tumor-bearing animals. Results. Spleens of progeny of unvaccinated rats had a significant decrease in the areas of follicles, germinal centers and the mantle layer after exp osure to carcinogens, while maternal vaccination resulted in a significant expansion of the progeny's splenic follicles and germinal centers, the zone s of B cell proliferation. The area of periarterial lymph sheaths (PALS) ex panded in these offspring, reflecting activation of the T-zone. Maternal va ccination also resulted in a significant rise of Fas ligand-positive lympho cytes in the follicles and PALS of their tumor-free offspring. Tumorigenesi s stimulated the Fas activity of B and T cells in the spleens, and this was much enhanced by maternal vaccination. Conclusions. Maternal vaccination before pregnancy results in altered morph ological and functional attributes of the splenic immune system of the offs pring. This increased immunoreactivity could reduce the risk of tumors in p rogeny of vaccinated mothers.