The first monoclonal anti-G1m(x) antibody: production and usefulness in haemagglutination-inhibition assay.

Murine monoclonal anti-human Ig allotype antibodies have been described for a limited number of specificities. Now the first monoclonal anti-G1m(x) antibody has been produced by fusion of lymph gland cells of a mouse injected with G1m(zax)-positive myeloma proteins with cells of the myeloma cell line SP2/0. Several limiting dilutions resulted in one antibody-producing hybridoma, clone 3A12. The specificity of monoclonal antibody (mAb) 3A12 in the direct haemagglutination assay, as well as in the haemagglutination-inhibition (HAI) assay, is described. Neither cross-reactivity nor nonspecific inhibition with G1m(x)-negative Ig was seen. Typing for the G1m(x) allotype with mAb 3A12 gave results which are identical to those obtained with the conventional human antisera. With the production of this mAb, it now is possible to discriminate between the four main G1m alleles not only by HAI assay but also by other assay systems, of which the preliminary results are promising.