Protection of young rats from acute Trypanosoma cruzi infection by interferon-gamma given to their mothers during pregnancy.

We investigated whether administration of interferon-gamma (IFN-gamma) to pregnant rats, infected or not with Trypanosoma cruzi, was likely to protect their offspring from trypanosomal infection. Upon mating with syngeneic sires, four groups of 70-day-old female 1 rats were subjected to one of the following procedures: treatment with recombinant rat (Rr)IFN-gamma 50,000 IU/rat five times/week for three weeks; infection with 1 x 10(6) trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-gamma treatment as given to the former group; the same protocol but IFN-gamma injections being replaced by injection with physiologic saline. Offspring were nursed by their mothers until weaning and then infected with a similar dose of T. cruzi. Pregnant rats showed no exacerbated infection but a self-resolving mild disease, regardless of whether or not they had received IFN-gamma. Maternal infection with T. cruzi and/or IFN-gamma treatment did not affect gestational outcome. Offspring born to both groups of IFN-gamma-treated mothers were almost fully protected from acute infection, and showed higher levels of anti-T. cruzi IgG antibodies when compared with young born to their respective IFN-gamma-untreated mothers. Measurements of IFN-gamma serum activities indicated that ameliorated acute disease in offspring whose mothers were given IFN-gamma during gestation, was not associated with increased levels of endogenously produced IFN-gamma.