Serum protein concentrations during Schistosoma mansoni infection in intact and T-cell deprived mice. II. Immunoglobulin G and antibodies specific for heterologous erythrocytes.

Mice infected with from twenty to fifty Schistosoma mansoni cercariae were found to have elevated serum IgG concentrations following patency of the infection, and the parasite-induced increase in concentration of IgG was dependent on the possession by the host of an intact T-cell lymphocyte pool. Following passive transfer of hyperimmune anti-sheep erythrocyte (SRBC) antibody, there was a more rapid decrease of haemolytic and haemagglutinating antibody titres in S. mansoni-infected, immunologically intact recipients than in uninfected intact mice, and infected or uninfected T-cell deprived mice. However, primary and secondary active immunization with SRBC resulted in similar patterns of serum antibody titre increase and decay in infected and uninfected intact mice over a time course of 140 days. The number of direct and indirect haemolytic plaque-forming (PFC) cells per million spleen cells was similar in S. mansoni-infected and uninfected immunologically intact mice 6 days after either primary or secondary challenge with SRBC. It is concluded that S. mansoni-infected immunologically intact mice challenged with heterologous erythrocytes synthesize anti-erythrocyte antibody at a greater rate than similarly challenged, uninfected mice.