Studies on the “Toxins” of Hemolytic Streptococci
Authors: Ando K. , Kurauchi K. , Nishimura H. 
Published: December 2022

Summary and Conclusions
The so-called nucleoproteins obtained from the bacterial sediments of a 0.5 per cent glucose broth culture of Streptococcus scarlatinæ by Woolridge's method, even in a highly diluted solution, gave a positive skin reaction in human beings which is indistinguishable from that caused by the ordinary Dick toxin. This substance is non-toxic for man and for the usual laboratory animals, it does not cause a skin reaction in white pigs, and its action is relatively heat-stable, but easily destroyable by tryptic digestion. When a culture filtrate of Streptococcus scarlatinæ (Dick toxin) is adjusted to pH about 4.0 with the addition of hydrochloric or acetic acid, a small precipitate occurs. This precipitate seems to be nucleoprotein in nature, as (a) it was precipitated by an antinucleoprotein serum which was prepared by the immunization of rabbit with nucleoprotein described above, (b) it did not cause a positive skin reaction in white pigs, (c) 86.2 per cent of 44 school boys tested, reacted in a similar manner to the intracutaneous injection of both the nucleoprotein solution and the solution of this acid precipitate from a culture filtrate, while 74.9 per cent of them reacted inversely to these solutions and to the specific toxin. A specific toxin was obtained from a culture filtrate of Streptococcus scarlatinæ in a relatively pure form by the repetition of alcohol- and acid-precipitation. This toxin may cause a positive skin reaction in both human beings and white pigs, as the culture filtrate itself. Skin reactions of human beings to this toxin and to the ordinary Dick toxin were in accordance with each other in the majority of cases examined (1241 individuals). The action of this toxin was practically destroyed by heating at 80°C. for thirty minutes and was neutralized by scarlatinal antitoxin. It is toxic for man and rabbit. Immunity may be obtained by injection of this purified toxin into susceptible human beings, and in the course of this immunization, the scarlatinoid syndrome was observed in some boys. This substance may, therefore, be considered to be the essential scarlatinal toxinexotoxin of Streptococcus scarlatinæ. The skin reaction to the so-called Dick toxin seems to be due to the presence of these two components, exotoxin and bacterial protein. The skin reaction to the bacterial protein seems to indicate an allergic state to this protein and that to the exotoxin is an indication of susceptibility to the specific exotoxin of Streptococcus scarlatinæ. For the susceptibility test to scarlet fever purified exotoxin free from bacterial proteins should be used. With respect to the response to the specific toxin and the nucleoprotein solution human beings may be grouped into four classes: The persons belonging to the first group are not only not immune or highly susceptible to the specific toxin, but also they are not allergic to the bacterial proteins of streptococcus; and those of the second group are allergic to the same proteins, but still susceptible to the specific toxin. The third group consists of persons who are immune to the specific toxin, but still allergic to the proteins; and persons of the fourth group are those who are not only immune to the specific toxin, but also not allergic to the bacterial proteins. In the first place, the specific toxin purified by us is heatlabile and seems not to act as an allergen; secondly, it may be neutralized by its antitoxin which may be produced by the immunization of horses or human beings with scarlatinal toxin or by suffering from scarlet fever, and also it may render positive reactors immune to this specific toxin by subcutaneous injections of it; and thirdly it may cause the scarlatinoid syndrome following an injection of a certain dose of it in highly susceptible human beings. For these three reasons the symptoms of scarlet fever may be interpreted as the intoxication caused by the exotoxin of Streptococcus scarlatinæ, but it can not be explained as an allergic phenomenon, as some authors believe. The white pig proved to be suitable as a test animal for the titration of scarlatinal toxin and antitoxin. For the same purpose a member of the first group of persons in our sense only may be suitable as a test object, if the ordinary Dick toxin be employed, but any person who is not sensitive to horse serum may be useful if purified exotoxin is available. If one uses the skin reactions in human beings as a criterion for the purification of scarlatinal toxin, it may happen that only the nucleoproteins are purified, while the specific toxin is lost. White pigs or persons of the first group in our sense must be used for this purpose. But, it must be borne in mind that even persons of the first group may give a positive skin reaction to a highly concentrated solution of nucleoproteins. Our crude, concentrated toxin prepared by precipitation with two volumes of alcohol from a culture filtrate may be conveniently used for the immunization and hyper-immunization of horses, as it can be concentrated more than ten times.