Enhancement of antigenic potency in vitro and immunogenicity in vivo by coupling the antigen to anti-immunoglobulin.
We have examined the effect of targeting an antigen to the immune system, by covalently coupling it to anti-immunoglobulin (Ig), on its efficacy for T cell stimulation in vitro and its immunogenicity for antibody production in vivo. In vitro, we compared the potency (for stimulation of a ferritin-specific T cell line) of free ferritin, ferritin coupled to goat antimouse IgM (heavy (H) chain specific), ferritin coupled to anti-IgG (H and light (L) chain specific), or ferritin coupled to anti-IgA (H chain specific), as well as a mixture of free ferritin plus goat anti-IgG. The ferritin coupled to anti-IgM or to anti-IgG (H + L), which could bind to surface Ig of B cells, stimulated T cell proliferation at concentrations of ferritin at least 10-fold lower than those required for the other forms of the antigen over the entire time course of the response, with 1000 rad-irradiated spleen cells as presenting cells. Because the goat antibodies were all of the same IgG isotype and coupling ratio, the failure of goat anti-IgA to enhance potency served as a control to exclude Fc receptor binding as the mechanism. The effect was not due to the nonspecific activation of B cells to become more efficient antigen-presenting cells, because mixtures of ferritin plus anti-IgG (H + L) had no effect, and the anti-IgG coupled to ferritin did not enhance presentation of myoglobin to a myoglobin-specific T cell line. The enhanced presentation of ferritin conjugated to goat anti-IgG (H + L) or to anti-IgM was sensitive to radiation doses greater than 2000 R, and was effective at less than one-tenth the number of spleen cells, consistent with the predominance of B cells as antigen-presenting cells for this form of the antigen rather than macrophages and dendritic cells only. When B cells and accessory cells were purified from T-depleted spleen cells, only the B cell preparation but not the accessory cell population manifested enhanced presentation of ferritin coupled to anti-IgG compared with free ferritin, and it was radiosensitive. Finally, allogeneic B cells could not mediate the enhancement in the presence of syngeneic splenic accessory cells (SAC); therefore, the enhancement was not due to shedding of immune complexes from B cells and subsequent presentation by SAC. We conclude that targeting the antigen to B cells as presenting cells greatly enhances its efficacy in vitro.(ABSTRACT TRUNCATED AT 400 WORDS)
Kawamura
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Berzofsky
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JA
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology*; D000917:Antibody Formation; D000938:Antigen-Presenting Cells / Q000276:immunology; D000941:Antigens / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D005293:Ferritins / Q000276:immunology*; D006041:Goats; D006736:Horses; D007074:Immunoglobulin G / Q000276:immunology*; D007143:Immunoglobulin Heavy Chains / Q000276:immunology; D007147:Immunoglobulin Light Chains / Q000276:immunology; D007075:Immunoglobulin M / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D013154:Spleen / Q000166:cytology
D000888:Antibodies, Anti-Idiotypic; D000941:Antigens; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007075:Immunoglobulin M; C044203:anti-IgM; D005293:Ferritins