Tuberculotoxins and Their Significance in Allergy and Neutralization Phenomena
Authors: Eberson Frederick , Sweeney Marion A. 
Published: January 2023

Conclusions and Summary
Intracutaneous and intraperitoneal studies were made with Berkefeld filtrates of cultures of tubercle bacilli in tuberculous and normal guinea pigs. Comparative studies included filtrates prepared from extracts of focal tuberculous tissues.
Neutralization tests were made by intracutaneous and intraperitoneal methods, using an immune serum prepared in the goat by intracutaneous injections of toxic filtrates over a period of two years.
The intracutaneous experiments resulted as follows: the reactions obtained with toxic filtrates were unlike those of tuberculin and confirmed our previous observations relating to the production of toxic substances by tubercle bacilli grown in suitable culture media; the immune goat serum contained antibodies that were demonstrable in the skin by passive transference to the tuberculous animal; combinations of immune goat serum and toxic filtrates in varying proportions exhibited neutralizing properties of the serum under certain conditions; and, when such proportions of material permitted, a simultaneous reaction of passively transferred local allergy. In the normal, non-tuberculous guinea pig controls these phenomena were not observed, indicating the specificity of these local reactions; filtrates prepared from focal tuberculous tissues in the guinea pig were inactive.
The consitutional or general reactions studied by means of intraperitoneal injections of test material were summarized as follows:
Toxic Berkefeld filtrates prepared from five to eighteen-day-old cultures of tubercle bacilli caused typical immediate or delayed reactions that resulted in death or a chain of symptoms followed by recovery. Heating the filtrate to a temperature of 100°C. for one to two hours modified or prevented symptoms. These reactions did not occur in the normal guinea pig. Throughout these experiments all tuberculous controls survived weeks or months beyond the time of specific tests.
Comparison of the behavior of filtrates with ordinary Old Tuberculin under identical conditions showed definitely marked qualitative and quantitative differences. Primarily, irrespective of the dosage, injections of diluted O.T. did not produce any immediate or delayed reactions that were in any manner characteristic or analogous with those elicited with the filtrates. From the quantitative standpoint also, the filtrates were not concentrated before use; the dose injected was proportionately smaller than that of tuberculin; and the cultures from which filtrates were prepared represented relatively short periods of bacterial growth (five to eighteen days), as against six to eight weeks for tuberculin. Filtrates from five-day cultures were found to be highly toxic.
Immune serum prepared in the goat by subcutaneous injections of toxic filtrates over a period of two years neutralized completely or lessened the toxic reactions obtained with filtrates alone. The results were considered specific for the following reasons: Normal goat serum failed to protect tuberculous guinea pigs under identical conditions; the filtrates were innocuous for the normal guinea pig; immune serum did not neutralize the lethal action of diluted tuberculin, and in this respect did not differ from normal goat serum with which comparative experimental tests were simultaneously made. Immune goat serum alone caused irregular reactions at times and, rarely, death, depending upon the dosage, indicating an allergic response that was passively induced. With normal serum alone the phenomenon was not observed.
Toxic filtrates of tubercle cultures appeared to contain antigenic and allergenic substances.
Filtrates prepared from emulsions of local tubercles in the skin of experimentally infected guinea pigs did not cause local and general reactions.
A more accurate interpretation of the clinical and immunity phenomena in tuberculosis is suggested by the data presented in this report.