Absorption of group A streptococcus anti-M typing sera with broken cells.

Group A streptococcus anti-M typing sera that cannot be made specific by absorption with whole streptococcus cells have been absorbed with the soluble and insoluble fractions of ruptured heterologous cells. The technique has been used successfully for preparing specific anti-M sera against eight serotypes of group A streptococcus. The method involves breakage of the absorbing cells in the presence of the antiserum, and incubation of the mixture at 37 C for 1 hr, followed by 3 to 5 days of incubation at 4 C. The procedure is useful for preparing specific antiserum from certain lots of unabsorbed antiserum that otherwise would have to be discarded because of undesirable cross-reactivity.