Serologic responses to Schistosoma japonicum: evaluation of total and parasite-specific immunoglobulins during the course of murine infection.

Mice with a primary infection of Schistosoma japonicum develop high levels of both total immunoglobulins and parasitic-specific antibodies, beginning about 1.5 wk after the onset of oviposition in the host. Radial immunodiffusion demonstrated an 18-fold, fivefold, and threefold increase in the levels of IgG1, IgM, and IgA, respectively, during the course of infection. Schistosoma japonicum-specific antibodies, as measured by an enzyme-linked immunoabsorbent assay, appeared and increased at about the same time as total immunoglobulins, and were predominantly of the IgG1 and IgM classes. The specific/ELISA response to a purified antigen from S. japonicum SEA was distinct from the total specific response to crude SEA. Hemagglutinating antibodies increased at 5 wk PI and remained at high levels for the duration of infection. Specific, circulating IgE measured by PCA appeared 6 wk PI, reaching a peak at 9 wk, and persisted at moderate levels throughout the infection period.