Human monoclonal antibodies heterogeneously express a human cross-reactive idiotype associated with immune function in Schistosoma japonicum infection.

Hybridomas secreting human monoclonal antibodies (hMAb) were derived from Epstein Barr Virus (EBV) transformed lymphocytes of a patient with acute Schistosoma japonicum infection. Three IgG1 hMAb SJ-D, SJ-E, and SJ-F bind soluble egg antigens (SEA) as determined by ELISA. These hMAb exhibit identical western blot profiles, recognizing an epitope(s) of multiple antigens with apparent molecular weights between 42 and 75 kDa. Serological analysis of these hMAb revealed a heterogeneity in their expression of a specific human S. japonicum anti-SEA associated cross reactive idiotype designated Hu SJ-CRIM. The differential expression of idiotypy by these hMAb correlates with immunosuppression of blastogenesis of lymphocytes from schistosomiasis patients. The level of suppression mediated by hMAb expressing high levels of Hu SJ-CRIM ranged from 41% to 52% (p < 0.05) for antigen and 36% to 43% for mitogen. In contrast, hMAb SJ-D which expressed over two fold lower levels Hu SR-CRIM, on a per weight basis showed no suppressive immune function. The data show the heterogeneous expression of human idiotype associated with S. japonicum infection and the correlation of idiotype expression with immune function.