The use of mouse/human chimaeric antibodies to investigate the roles of different antibody isotypes, including IgA2, in the killing of Schistosoma mansoni schistosomula by eosinophils.

We report the use of a matched set of mice/human chimaeric antibodies, directed against the 5-iodo-4-hydroxyl-3-nitrophenacetyl (NIP) hapten, to investigate the roles of different human isotypes in antibody-mediated eosinophil-dependent killing of schistosomula. The chimaeric antibodies consist of mouse VH, VL and CL regions with human gamma 1, gamma 2, gamma 3 (2 allotypes), gamma 4, alpha 2, mu or epsilon CH regions and were used in in vitro assays with human eosinophils and NIP-coated S. mansoni schistosomula. Some anti-NIP isotypes mediated high levels of killing, which was specific for NIP-coated larvae, and we suggest that these antibodies will be a valuable tool for studies on the role of antibody isotypes in anti-schistosome immune effector mechanisms. In particular, this method directly demonstrated, for the first time, that IgA is highly effective in mediating the killing of metazoan parasites by human eosinophils.