DIFFERENTIAL RESPONSIVENESS OF HUMANS WITH EARLY-STAGE SCHISTOSOMIASIS HAEMATOBIUM TO SCHISTOSOMA-HAEMATOBIUM SOLUBLE ADULT-WORM AND EGG ANTIGENS

Schoolchildren (7-8 years old) infected with Schistosoma haematobium w ere tested for lymphocyte proliferative responses, in vitro granuloma formation (IVGF), and cytokine release in T-cell Western assays and fo r serum antibody reactivity by enzyme-linked immunosorbent assay (ELIS A) and immunoblotting against S. haematobium soluble adult-worm (SAWA) and egg (SEA) antigens. The lymphoproliferative response rate of indi vidual subjects against 10 SAWA and 15 SEA electroseparated bands rang ed from 0 to 33 % and from 11 to 66 %, respectively. The SAWA bands es sentially failed to elicit significant IVGF, in contrast to the SEA ba nds, all of which were capable of inducing IVGF from peripheral blood mononuclear cells (PBMC) of 30-80 % of individual donors. The exclusiv e ability of SEA bands to induce IVGF could not be attributed to selec tive release of interleukin 2 (IL-2), IL-4, or interferon-gamma, as SE A and SAWA bands were capable of eliciting release of a similar array of cytokines in supernatants of 4-day PBMC cultures. The antibody resp onse to SEA was stronger than that to SAWA, yet the proportion of SAWA bands binding humoral antibodies of individual donors was significant ly larger than that observed for SEA. The study thus suggests that hum ans with early-stage S. haematobium infection respond poorly to SAWA b ut mount strong cellular immune responses to SEA that result in granul oma and antibody formation.