Immunological consequences of intestinal helminth infections. Humoral responses to ovalbumin.

Humoral responses to ovalbumin (OA) administered i.p. with Al(OH)3 were depressed in C57BL mice immunized 5-13 days after infection with N. dubius, but not N. brasiliensis or T. muris. These two parasites induced elevated IgM responses, possibly as a result of systemic contact with parasite larvae or debris since i.v. administered N. dubius also increased IgM titres to OA. Depression of anti-OA IgG titres by N. dubius was also observed in infected BALB/c and CBA mice given OA-Al(OH)3 (i.p.), but not in C57BL mice given OA-Al(OH)3 (s.c.), OA-FCA (i.p. or s.c.), or OA-B, pertussis (i.p.). These findings suggest that local effects of N. dubius within the peritoneum reduce the adjuvanticity of Al(OH)3, resulting in depressed responses to OA-Al(OH)3.