Tetanus antitoxin titration by haemagglutination at a low level of test

Abstract

An investigation has been made of methods of estimating the antitoxin content of small samples of human sera by haemagglutination procedures.The direct agglutination test appears to be satisfactory when dealing with groups of sera, but was unreliable for testing individual sera.The discrepancies observed in the direct agglutination test were greatly reduced by adopting an agglutination inhibition test at the LA/100 level of test.The difference in agglutinating capacity of both avid and non-avid sera per in vivo unit of antitoxin did not appear to be related to avidity.