SCHISTOSOMA-JAPONICUM SOLUBLE EGG ANTIGENS ACTIVATE NAIVE B-CELLS TO PRODUCE ANTIBODIES - DEFINITION OF PARASITE MECHANISMS OF IMMUNE DEVIATION

This study analysed the effect of Schistosoma japonicum egg antigens ( SEA) on the activation of lymphocytes from naive mice. T cells were fo und to be unaffected by SEA. B cells, however, were activated by SEA w ithout participation of adherent cells such as macrophages. B-cell act ivating factor(s) in SEA were distributed into a fraction of M(r) 120, 000 and a fraction of M(r) 650,000 by gel filtration. However, a fract ion of M(r) 120,000 demonstrated the presence of a limited number of c omponents by polyacrylamide gel electrophoresis (PAGE) under non-denat uring conditions. These activating factor(s) were destroyed by peroxid ase oxidation, heat treatment, chymotrypsin and trypsin digestion. The se results indicate that the B-cell activating factor(s) in SEA contai n both carbohydrate and protein. IgM antibodies were detected in the c ulture supernatant of SEA-activated B cells after 48 hr in culture, bu t IgG antibodies were undetected in culture. These antibodies did not react with SEA but reacted with sheep, horse, mouse red blood cells, c arbonic anhydrase and autoantigens in myelinated nerve fibres of cereb rum as well as luminal surface and parietal cells of the stomach of na ive mice. Thus our data demonstrated that SEA directly stimulates naiv e B cells to produce antibodies against heterophile and autologous ant igens.