Experimental disseminated strongyloidiasis in Erythrocebus patas. II. Immunology.

Parasite-specific humoral and cellular immune responses were evaluated in seven Erythrocebus patas monkeys experimentally infected with a Southeast Asian strain of Strongyloides stercoralis. Most animals developed high titers of anti-larval surface IgG antibody (as evaluated by the indirect immunofluorescence test), and all animals tested developed specific IgE antibody (as shown by the in vitro histamine release test). Modest lymphoproliferative responses to S. stercoralis antigens were demonstrated in most animals during the early phase of the infection (days 20-40), but disappeared later. Steroid treatment (prednisone, 12.5 mg/kg on alternate days) was given to three animals, but did not appear to significantly affect the immune parameters tested. The degree of the immune responses to S. stercoralis larval antigens did not correlate well with the course of the infection, and several animals died of disseminated disease in spite of demonstrable humoral and cellular responses to these antigens. We suggest therefore that other factors, such as local intestinal immune and nonimmune mechanisms may be of importance in protection against disseminated strongyloidiasis.