Mast cells in severely T-cell depleted rats and the response to infestation with Nippostrongylus brasiliensis.

The effect of severe T-cell depletion on mucosal mast cells of the small intestine and on connective tissue mast cells has been studied in adult thymectomized, irradiated, bone marrow reconstituted (B) rats. Under normal conditions, intestinal mucosal mast cell numbers do not differ significantly between B rats, normal age matched rats and non-thymectomized irradiated controls. Connective tissue mast cells are significantly fewer in the tongues of B rats than in normal rats, but the difference is atributable to an effect of irradiation. Infestation with Nippostrongylus brasiliensis produced approximately equal increases in mucosal mast cells in non-thymectomized irradiation controls and in normal rats. In B rats there was no increase in mucosal mast cells following infestation. B rats failed to expel the parasites normally. Failure of mast cell proliferation was not due to the effects of the persisting worm burden. Antihelminthic treatment at the time of worm expulsion by normal rats did not reveal a hitherto masked mast cell response in B rats. Nippostrongylus infestation did not reveal evidence of thymus-dependency of connective tissue mast cells. As in athymic nude mice, mucosal mast cells in the rat have been shown to be T-cell dependent during the proliferation that follows infestation with an intestinal nematode parasite.