Passive haemagglutination for estimation of early and late anti-human gamma-globulin antibodies.

The influence of various concentrations of human γ-globulin (HGG) employed to sensitize tanned sheep erythrocytes on haemagglutination titres with various early and late mouse and rabbit antisera to HGG has been studied. The concentration of HGG employed to sensitize tanned erythrocytes which gives the highest haemagglutination titres with early, mercaptoethanol-sensitive antibodies was not optimal for obtaining highest haemagglutination titres with late, mercaptoethanol-insensitive antibodies. Similar results were obtained with heavy and light sucrose gradient ultracentrifugation fractions of a late and early rabbit antiserum. These findings may account for past discrepancies and should be considered when employing the haemagglutination test to detect early and late antibodies.