Differences between the large and small intestine in the immunodominant amoebic proteins recognized by IgG and IgA antibodies in BALB/c mice

We have previously reported that there are differences in the number of predominant amoebic antigens recognized by serum and small intestinal antibodies induced after local and systemic immunization with glutarldehyde-fixed Entamoeba histolytica trophozoites (GFT) in BALB/c mice, by an immunoblot analysis. Moreover, by enzyme-linked immunosorbent assay (ELISA) analysis, we found differences in the antiamoebic antibody isotype patterns elicited at the large and small intestines. To further characterize the antiamoebic immune response induced in BALB/c mice, after local (oral and rectal) and systemic (intraperitoneal and intramuscular) immunization with GFT, we performed an immunoblot analysis of the amoebic proteins predominantly recognized by immunoglobulins (Ig)G, IgA and IgM in the serum and in the small and large intestines. The present work shows differences between the large and small intestine in the IgG- and IgA-antibody recognition pattern of amoebic proteins, thus confirming and extending our previous findings supporting the compartmentalization of the intestinal immune response. Furthermore, our reported observation that there are differences in the amoebic proteins predominantly recognized by antibodies of different isotypes was extended to the intestines, as some proteins with relative molecular weights of 24-25, 66, 140 kDa are strongly recognized by IgG but not by other antibody isotypes.