Specificity of anti-human IgG antibodies in antiglobulin (Coombs) sera.

The agglutination test with latex particles coated with aggregated human IgG was introduced into the evaluation of Coombs serum as an additional test for anti-IgG antibody activity. In Coombs sera prepared by the conventional immunization method employing Freund's adjuvant, latex agglutination titers were found much lower than those of anti-D-coated red cell agglutination. On the other hand, in sera prepared by other immunization methods, such as the one according to Haynes and Chaplin (1971), anti-IgG antibody response was readily observed by IgG-coated latex agglutination. Specificity of anti-IgG antibodies in the latter sera seems to be predominantly directed to aggregated human IgG.