Distribution of Entamoeba histolytica Gal/GalNAc lectin-specific antibody response in an endemic area.

To demonstrate the dynamics of specific antibody isotypes against Entamoeba histolytica Gal/GalNAc adhesin and its correlation, if any, with the development of immunity, we evaluated subjects suffering from a spectrum of amoebic infections ranging from amoebic liver abscess (ALA) to asymptomatic cyst passers. The quantitative analysis of antibody levels was done in the sera by enzyme-linked immunosorbent assay. Gal/GalNAc adhesin-specific immunoglobulin G (IgG) was higher in ALA (and their follow-ups) and intestinal amoebiasis cases as compared with asymptomatic cyst passers (P < 0.05). Among the isotypes of IgG, high levels of IgG1 (60% of the total IgG concentration), suggestive of T-helper 2-type response, was associated with ALA cases. Intestinal amoebiasis cases and cyst passers had high percentage of IgG1 and IgG4 antibodies as compared with per cent IgG2 and IgG3 (of the total IgG), whereas follow-up cases of ALA had predominantly IgG2 and IgG3 isotypes of antibodies. Gal/GalNAc lectin-specific IgM antibodies were maximum in cases of intestinal amoebiasis. ALA cases and their follow-ups had significantly lower levels of Gal/GalNAc-specific IgM levels as compared with cyst passers (P < 0.05). Gal/GalNAc adhesin-specific IgA antibodies were raised maximally in intestinal amoebic infection cases. ALA cases and their 3-month follow-ups had significantly higher concentrations of lectin-specific IgA (P < 0.05) as compared with the healthy subjects.