MECHANISMS FOR MUCOSAL IMMUNOGENICITY AND ADJUVANCY OF ESCHERICHIA-COLI LABILE ENTEROTOXIN

Escherichia coli labile toxin (LT) was assessed as mucosal immunogen a nd as adjuvant for tetanus toroid (TT) in mice, After oral administrat ion of LT, C57BL/6 (H-2(b)) and BALB/c (H-2(d)) mice were high mucosal and serum antibody responders, while C3H/HeN (H-2(k)) mice were low r esponders. High responders exhibited mainly serum Ige (including IgG1, IgG2a, and IgG2b), as well as IgM and IgA, while mucosal responses we re IgA. Analysis of LT-B-specific CD4(+) T helper (Th) cells from Peye r's patches (PP) or from spleen revealed a mixed Th1 (interferon-gamma ) and Th2 (interleukin-4 and -5) cell pattern, Oral LT given with TT i nduced TT-specific response patterns identical to LT-B, Analysis of mR NA from TT-specific PP CD4(+) Th cells also revealed a mixed Th1- and Th2-type response. Thus, antibody response profiles induced by LT are regulated by both CD4(+) Th1 and Th2 cell types.