title: Immunopotentiation by SGP and Quil A. II. Identification of responding cell populations.
abstract: The adjuvants SGP (a starch-acrylamide polymer) and Quil A (purified saponin) were shown to markedly augment antibody responses to T-independent (TI) antigens, suggesting that their adjuvant effects may be at least partially mediated through B cells. The ability of both adjuvants to augment primary responses to trinitrophenyl (TNP)-Ficoll (TI-2 antigen) in athymic nude mice further suggested these adjuvants affect B cells. SGP, however, did not induce a response to the T-dependent (TD) antigen dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH) in athymic nude mice, indicating it was unable to replace the requirement for T-helper cells for responses to TD antigens. Responses to TNP-lipopolysaccharide (LPS) were augmented by SGP in CBA/N X Balb/c immune defective (xid) mice. However, SGP was unable to induce a response to TNP-Ficoll in xid mice. The SGP and Quil A augmented responses to TNP-Ficoll were completely inhibited by the mitotic inhibitor, Velban, indicating that SGP and Quil A increased the plaque-forming cell (PFC) response primarily by stimulating cell proliferation, and not by recruitment of antigen-reactive cells. The effects of the adjuvants on secondary responses were investigated using adoptive transfer experiments. SGP and A1(OH)3 both increased the induction of hapten-specific memory B cells in mice primed with DNP-KLH. SGP, Quil A, and A1(OH)3 also increased priming of carrier specific T cells. Priming of memory B cells with DNP-KLH and either A1(OH)3 or SGP was prevented when T cells were depleted with anti-lymphocyte serum (ALS) at the time of antigen priming, indicating that the augmentation of memory B-cell priming by SGP and A1(OH)3 was dependent on the presence of functional T cells. SGP and Quil A were both unable to augment memory cell induction to the TI antigen, TNP-Ficoll, even though both adjuvants markedly augmented primary IgM and IgG responses to this antigen. Based on these results, it is suggested that SGP and Quil A can mediate their adjuvant effects primarily by a direct or indirect effect on B cells although the adjuvants may also affect T cells to some extent.
mesh_terms: D000180:Acrylic Resins / Q000494:pharmacology*; D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D000941:Antigens / Q000276:immunology; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002455:Cell Division; D005260:Female; D007156:Immunologic Memory / Q000187:drug effects; D008213:Lymphocyte Activation; D051379:Mice; D008819:Mice, Nude; D062605:Quillaja Saponins; D012503:Saponins / Q000494:pharmacology*; D013213:Starch / Q000031:analogs & derivatives* / Q000494:pharmacology; D013268:Stimulation, Chemical; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
chemical_list: D000180:Acrylic Resins; D000276:Adjuvants, Immunologic; D000941:Antigens; D062605:Quillaja Saponins; D012503:Saponins; C046386:Quil A; C050104:starch-acrylamide polymer; D013213:Starch