INDUCTION OF PARASITE ANTIGEN-SPECIFIC ANTIBODY-RESPONSES IN UNSENSITIZED HUMAN B-CELLS IS DEPENDENT ON THE PRESENCE OF CYTOKINES AFTER T-CELL PRIMING

Using two recombinant filarial protein Ags and keyhole limpet hemocyan in, we sensitized T cells from uninfected, nonatopic individuals in su ch a manner that they were able to provide help for the selective indu ction of an Ag-specific Ab response, IL-2 and IL-4 were shown to be cr itical for sensitizing the T cells; once sensitized, these T cells cou ld provide the necessary signals for B cells to produce Ag-specific Ab s, provided that IL-4 (or IL-2) was supplied exogenously, Primary expo sure of T cells to IFN-gamma, but not to IL-12, prevented the Ag-sensi tized T cells from helping B cells to produce specific Abs, apart from the IgG2 isotype, These data suggest that Ab-producing B cells of a d efined Ag specificity and isotype can be generated differentially afte r in vitro priming of human T cells by Ag, providing regulatory cytoki nes are also present.