[Further data on the dependence of the agglutination titre of T4 streptococci on the haptoglobin type (Hp 2-2 and Hp 2-1)].

Anti-streptococcal T4 titres in human sera tend to be higher in normal sera of the Hp type hp 2-2 than in normal sera of hp 2-1 subjects. If the sera are heated above a temperature of 50 degrees C the difference disappeared and the titres are reduced. When heating sera to 63 degrees for 10 min no agglutination activity for T4 streptococci can be observed.