Identification and characterization of Schistosoma mansoni antigens recognized by T and B lymphocytes of humans with early active intestinal and/or urinary schistosomiasis.

Schistosome antigens selected as vaccine candidates should induce in the majority of humans T and B cell-mediated immunity that results in protection against infection. As a first step towards the identification of such antigens, we attempted to define and characterize the soluble adult Schistosoma mansoni worm antigen (SAWA) bands that are recognized by serum antibodies and/or peripheral blood mononuclear cells of Egyptian children with early active S. mansoni and/or S. haematobium infection. Considerable inter-subject variation was observed in the SAWA bands recognized by antibodies and T lymphocytes, as demonstrated by Western blotting and T cell Western assays, respectively. The humoral response rate for the separated SAWA bands varied between 0% and 88% of infected subjects. The bands of 153, 144, 38 and 32 kDa reacted with the sera of 60 to 88% of infected subjects but not with the sera of uninfected controls. The bands of 144, 38, 32 and 18 kDa elicited proliferative responses in the lymphocytes of 42-63% of infected subjects. It was thus concluded that the SAWA bands of 144, 38 and 32 kDa are likely to carry T and B cell epitopes that could stimulate immune responses in a majority of individuals. The selected bands (144, 38 and 32 kDa) were found to include glycoproteins containing D-mannopyranosyl or glycosyl residues, and respectively 62.5, 46 and 55% amino acids by weight. The amino acid molar ratios of these bands were completely different.