Immunodulation of rat serum and mucosal antibody responses to Entamoeba histolytica trophozoites by beta-1,3-glucan and cholera toxin

Systemic and mucosal and immune responses can be manipulated with immunomod ulators. Here we show the modulatory effects of cholera toxin (CT) and beta -1,3-glucan (GLU) on the rat antiamebic serum and fecal antibody responses to one or four intraperitoneal (IP) or intragastric (IG) doses of glutaral dehyde-fixed Entamoeba histolytica trophozoites (GFT). One IP dose of GPT m aximized serum IgM and IgG antiamebic antibodies on days 4 and 9, respectiv ely; CT coadministration increased IgM antibodies, whereas IgG titers incre ased with CT or GLU; coproantibodies were undetectable after GFT alone or c oadministered with GLU, whereas CT coadministration maximized fecal IgA ant ibodies on day 6. One IG dose of GFT alone increased serum IgM and IgG anti bodies 2.5 times and no further increases were detected using GLU, whereas CT doubled serum IgG antibodies; GFT did not affect the coproantibody respo nses, whereas GLU coadministration maximized IgG coproantibody levels on da y 6 and CT increased IgG and IgA coproantibody levels on the same day. On t he other hand, four IG doses of GFT alone or with GLU induced tolerance, wh ereas GFT alone via the IP route increased serum antibodies slightly and GL U coadministration increased serum IgG antibody titers 300-fold. CT coadmin istration by both routes increased IgA coproantibodies, and simultaneous CT +GLU coadministration induced lower responses than either CT or GLU. Differ ent antiamebic immune responses might therefore be attained through the use of different immunization routes and immunomodulators to induce protective immunity against intestinal or extraintestinal amebiasis. (C) 2000 Academi c Press.