THE INFLUENCE OF SEX AND AGE ON ANTIBODY ISOTYPE RESPONSES TO SCHISTOSOMA-MANSONI AND SCHISTOSOMA-JAPONICUM IN HUMAN-POPULATIONS IN KENYA AND THE PHILIPPINES

We have investigated the effects of host age and sex on human antibody isotype responses to Schistosoma mansoni and Schistosoma japonicum ad ult worm (AW) and soluble egg (SEA) antigens, using sera from subjects in Kenya and the Philippines. Similar trends with age were observed b etween the two populations despite host, parasite and environmental di fferences between the two geographical locations. IgE to AW increased with age, whereas most isotype responses to SEA decreased with age. Ig G,, IgG, and IgG, subclass responses to adult worm, however, did not s how a broadly rising or falling pattern with age. Males were found to have higher IgG,, IgG, and IgE to AW in both populations. This sex dif ference remained significant in the Kenyan population even after contr olling statistically for confounding factors such as age and differenc es in intensity of infection. Analysis of S. mansoni and S. japonicum adult worm antigens reactive with IgE revealed a predominant 22 kDa ba nd in both parasites. Only those individuals with relatively high IgE titres specifically reactive with S. mansoni or S. japonicum AW had de tectable IgE against Sj22 or Sm22.