Genetic control of immune response to a purified Schistosoma mansoni antigen. II. Establishment and characterization of specific I-A and I-E restricted T-cell clones.

T-cell lines and clones specific for a partially protective schistosome antigen (9B antigen) were established from mice immunized with such antigen. The H-2 congenic strains B10.A which express both I-A and I-E class II gene products of the major histocompatibility complex (MHC) and B10.A(4R) which only express I-A molecules were used in these studies. The specific T-cell lines recognized the 9B antigen in the context of either A or E molecules, but both class II antigens were necessary for maximal stimulation of the T-cell lines in lymphocyte proliferation assays. T-cell clones were derived from these lines and their MHC restriction was investigated. Both I-A and I-E restricted clones could be isolated. All clones were specific for 9B antigen showing different degrees of cross-reactivity with a total schistosome extract (CA sonicate). A correlation between the fine specificity of the clones and the expression of class II antigens was demonstrated. Clones specific for 9B antigen, or which reacted to the same extent with 9B antigen and CA sonicate, were I-A restricted, whereas clones which proliferated more in the presence of CA sonicate were all I-E restricted. This suggests that I-E restricted clones recognize more cross-reactive epitopes than I-A restricted clones. These antigen-specific T-cell clones should provide a useful tool for examining the role of class II antigens in the modulation of protective immune response during Schistosoma mansoni infection.