Humoral immune responses in human infection with the whipworm Trichuris trichiura

The humoral immune response to infection with Trichuris trichirua was investigated by ELISA and immunoblotting using human sera from the Caribbean island of St Lucia. Immunoblot analysis of the degree of cross-reactivity with the related trichuroid Trichinella spiralis and with the other commonly co-existent nematodes, Ascaris lumbricoides and Toxocara canis, was carried out using selected sera. The IgM, IgA, IgE, and IgG subclass antibody levels were measured in ELISA using a detergent solubilized extract of adult T. trichiura. The IgG and IgE responses were highly Trichuris specific. Anti-T. trichiura IgM responses were totally cross-reactive with A. lumbricoides and were completely ablated by pre-incubation of sera with Ascaris antigen. The IgG response was predominantly of the IgG1 subclass with a minimal IgG3 response. Only 1 person out of 130 tested had a detectable IgG3 response. The IgG2 response appeared to be directed primarily against carbohydrate or polysaccharide antigens as pre-treatment of the ELISA plates with poly-L-lysine was necessary before a response could be detected. These data are the first demonstration of human isotypic responses to infection with T. trichiura.