Immunocapture assay for quantification of human IgA antibodies to parasite antigenic enzymes. Application with the alkaline phosphatase of Schistosoma mansoni.

Conditions are described for using solid phase adsorbed jacalins in an immunocapture assay for IgA antibodies to the alkaline phosphatase of Schistosoma mansoni. Microtiter plates were activated with polylysine and jacalins were covalently adsorbed by means of glutaraldehyde. From three different jacalins, the one purified from seeds of Artocarpus tonkinensis showed the lowest non-specific adsorption and was used for further studies. Comparing solutions of bovine serum albumin, ovalbumin and Tween 20, it was shown that the latter was most successful in blocking non-specific adsorption. Low serum dilutions resulted in a less efficient IgA capture by the adsorbed jacalin than higher dilutions. Under optimal working conditions, a high correlation could be shown between the presence of specific anti-alkaline phosphatase antibodies of IgA isotype and IgG isotype.