ACTIVATION OF INTERLEUKIN-4-SECRETING AND INTERLEUKIN-6-SECRETING CELLS BY HIV-SPECIFIC SYNTHETIC PEPTIDES

Peptides were synthesized in which the type-specific determinant of th e V3 loop region of gp120 (SP10) was expressed C terminal to a conserv ed T helper epitope (T1) on the same molecule. These T1-SP10 peptides can stimulate both cell-mediated and humoral immune responses. The cur rent work used a novel approach to study the nature and specificity of the response elicited by these peptides. Cytokine-specific ELIspot as says were used to examine the number, kinetics and fine specificity of cells induced to secrete IL-4 and IL-6 in mice immunized with T1-SP10 peptides. Results indicate that the peptides activated cytokine-secre ting cells in a dose-dependent manner in vivo. In vitro restimulation experiments demonstrated that both the SP10 and T1 regions contributed to this activation. Consistent with previous studies, mice sequential ly immunized with peptides expressing different V3 loop regions genera ted B cell responses that were larger and more cross-reactive than tho se induced by a single peptide. Sequential immunizations had less effe ct on the number or specificity of the cytokine-producing cells.