The study of antibodies in man following streptococcal infections has indicated the presence of some antibodies which play a certain role of immunological importance in the infection process. The type-specific antibody to the M antigen of Group A streptococci has been generally considered to be responsible for the antibacterial immunity, and the antibody to the erythrogenic toxin has been assumed to be capable of preventing the occurrence of scarlet fever. However, the immunological significance of antibodies to various extracellular products, such as antistreptolysin O (ASL), antistreptokinase, antihyaluronidase, etc., in human infections has not been well defined, although numerous previous studies have contributed a great deal to the knowledge of the antibody response.
In the first report of the present series of investigations (Kusama et al., 1962), the fundamental aspects of the distribution of ASL titers in various age groups weree presented, and it was shown that the experience of streptococcal infections in the past has divided a population into the positive and negative groups with respect to the ASL response. With these informations in mind, investigations were undertaken to disclose such mechanics of ASL response in scarlet fever patients as the relationship of the amplitude of the response to the initial titer and to the serologic types of infecting organisms. Furthermore, a special attention was paid to the difference in the magnitude of the antibody response following a newly established infection between those who belonged to the positive and negative groups at the time of infection.
