Characterization of fractionated Schistosoma mansoni soluble adult worm antigens that elicit human cell proliferation and granuloma formation in vitro

Soluble adult worm antigens (SWAP) of Schistosoma nansoni were fractionated by fast protein liquid chromatography (FPLC) system, using Q-Sepharose anion-exchange resin, in order to characterize antigenic fractions that may elicit cell responses in human schistosomiasis. SWAP fractions were eluted by 20 mM Tris-HCl solution (pH 9.6) with an increasing gradient of 1 hz NaCl. The FPLC system was able to resolve 6 fractions, enumerated I to VI, according to the NaCl gradient. The analysis of each fraction on SDS-PAGE showed that fractions I to IV were constituted by multiple protein bands with M(r) ranging from 21 to > 200 kDa. Large amounts of nucleic acids were evidenced in fractions V and VI, as revealed by ethidium bromide staining of agarose electrophoresis gels. Using ELISA, it was shown that sera from chronic schistosomiasis patients contained antibodies that recognized antigens in practically all fractions. Studies were designed to investigate the capacity of these fractions to induce cell proliferation and granuloma formation. It was demonstrated that fraction III stimulated a significant proliferative response of peripheral blood mononuclear cells (PBMC) from chronic schistosomiasis patients. However, fraction III coupled to polyacrylamide beads induced small granuloma formation in vitro, whereas beads coated with fractions I, II and V were able to induce significant granuloma reactions.