Although the immunologic response to infection with the beta hemolytic streptococcus has interested investigators for many years, they have encountered technical difficulty because of the variability of the response with different strains when determined by means of precipitation, agglutination or complement-fixation tests. The recent development of technics for the determination of the streptococcic antihemolysin titer and antifibrinolytic property of blood has made it possible to reconsider the problem by employing methods which are not seriously influenced by differences between strains of organisms in the host and in the test tube, provided the organisms are of human origin.
It has long been recognized that there is a substance in the filtrates of cultures of hemolytic streptococci which causes disintegration of red blood cells.1 It was subsequently observed that the hemolytic action of such filtrates could be inhibited by the blood of laboratory animals and man under certain conditions.2
LIPPARD VW, JOHNSON P. I. ANTIFIBRINOLYSIN AND ANTISTREPTOLYSIN RESPONSE. Am J Dis Child. 1935;49(6):1411-1429. doi:10.1001/archpedi.1935.01970060015002