Immunological studies on Nippostrongylus brasiliensis infection in the rat: The role of local anaphylaxis

Abstract

The role of local anaphylaxis in the immune expulsion of adult Nippostrongylus brasiliensis from the intestine of the rat has been investigated. The intravenous injection of the dye, Evans Blue, into rats harboring an infection of adult N. brasiliensis demonstrated areas of increased capillary permeability in the sites occupied by the worms. Anaphylactic reactions were produced when an extract of adult N. brasiliensis was injected into rats rendered immune either by previous infection or by serum transfer. The manifestations of this reaction in the gut were clearly seen when Evans Blue was injected intravenously along with the antigen. Neither the antihistamine substance, mepyramine maleate, nor the anti-5-hydroxy-tryptamine drug, lysergic acid, could abolish the anaphylactic reaction described above. Both compounds were also without effect on the self-cure reaction. The compound promethazine hydrochloride which has a more prolonged antihistaminic effect than mepyramine maleate did have some modifying influence on the self-cure reaction. A cortisone derivative, betamethasone, when administered from the 9th day of the infection was able to prevent the characteristic self-cure of an N. brasiliensis infection. This compound also prevented the anaphylactic reaction when adult antigen was injected into an immune rat. The results are discussed in relation to the mechanism of the self-cure reaction.