Cytotoxins

CYTOTOXINS (from the Greek kytos—cell and toxicon—poison), cellular poisons with the character of antibodies. Cytotoxins are obtained, for the most part, artificially by the parenteral introduction of corresponding cellular elements into an organism. Immunization with cellular material is not strictly necessary to obtain cytotoxins; it has been possible to obtain them by immunizing with nucleoproteins of the corresponding organ. The question of the suitability of products of incomplete protein breakdown of organs for this purpose remains unresolved. All cytotoxins are constructed according to the same type and consist of two components: an amboceptor and a complement; the corresponding cytotoxic effect is realized through the synergy of these latter (see Hemolysis, hematolysis). The most important known cytotoxins are leukotoxins (against leukocytes), epitheliotoxins, spermatotoxins, neurotoxins, hepatotoxins, and nephrotoxins. Cytotoxins against the thyroid (Mankovsky) and the pancreas (Sakharov) have also been obtained. Certain practical expectations were associated with many of these cytotoxins, although they were not always justified. Thus, Metchnikoff unsuccessfully attempted to use leukotoxic serum to combat macrophages in senile atrophic processes. An attempt to treat cancer with epitheliotoxic serum was also unsuccessful. Conversely, the idea of using spermatotoxins for the purpose of preventing conception led to positive results in experiments by creating both passive and active spermatotoxic immunity in animals. According to the Arndt-Schulz rule, many poisonous substances in small doses can have the opposite, stimulating effect, which was demonstrated by Metchnikoff, London, Belonovsky, and Besredka for hemolysins and leukotoxins. Later, an attempt was made to use neurotoxins in therapeutic forms (Sakharov, Lifshits, Khoroshko) for such afflictions of the central nervous system as progressive paralysis, schizophrenia, etc. The widespread use of cytotoxins in large doses encounters the fact of their insufficient organ specificity; for example, epitheliotoxic serum acts not only on epithelium but also hemolyzes. Heterocytotoxins, isocytotoxins, and autocytotoxins are distinguished. The first are formed upon the introduction of an antigen foreign to the given animal species. Isocytotoxins are obtained by immunizing an animal with cells of the same animal species; autocytotoxins are obtained by immunizing with cells of the immunized animal itself. The possibility of the formation of isocytotoxins was proven by Ehrlich and Morgenroth for erythrocytes, and of autocytotoxins for spermatozoa (Metalnikov) and kidney cells (Lindeman, Nefedyev).