Leucocytolysin

LEUCOCYTOLYSIN, syn. leucolysin, a substance that dissolves white blood cells. Until recently, this name referred to a special substance (or property) of the so-called leucotoxic serum, belonging to the group of cytolyzins and, like any cytolyzin, consisting of two components—an amboceptor and complement. Such an artificial L. can be obtained by the general principle—by immunizing an animal with the corresponding antigen, in this case—by introducing white blood cells of one animal species into an animal of another species. In addition to such artificially obtained L., there is also the natural L. discovered by Van de Velde, secreted by staphylococci and named leucocidin. The latter is constructed on the same type, i.e., just like, for example, hemolysin. Significantly later, another L. was discovered, also secreted under natural conditions: this is the L. produced by the spleen. Extracts from the spleens of different animals have sharply leucocytolytic properties, whereas extracts from the liver, on the contrary, protect white blood cells from disintegration (I. I. Manukhin, G. P. Sakharov and E. S. Ivanitsky-Vasilenko), so that in the latter case one could speak of anti-leucocytolysins. I. I. Manukhin subsequently pointed out the fact of an increase in the leucocytolytic properties of blood when the spleen is irradiated with small, "exciting" doses of X-rays, and conversely, a decrease in them with simultaneous leucocytosis as a result of similar exposure to the liver, and G. P. Sakharov and S. S. Zubov subjected the question of the spleen's L. to further development. It turned out that in the secretion of L. by the spleen, it is not difficult to convince oneself ad oculos in experiments on an isolated organ according to Kravkov (L. in the perfusion fluid). Whether this substance is identical with the well-known L. of leucotoxic serum, obtained by immunizing an animal with white blood cells, is unknown, but one thing is certain: it is of an enzymatic nature and is destroyed by heating at 56° for 1/2 hour. The leucocytolytic function of the spleen is quite labile in terms of sensitivity to various factors acting on it, both hormonal and non-hormonal: thus, more or less inhibitory effects are exerted by organotherapeutic preparations such as adrenaline, pituitrin, thyreoglandol, insulin, then acids; from alkaloids—quinine and slightly atropine; whereas spermine and epiphysan (extract from the epiphysis) stimulate; alkalis; slightly—pilocarpine. The liver secret (perfusion fluid), on the contrary, has anti-leucocytolytic properties: when mixed with L., it neutralizes it, and white blood cells acquire greater resistance to leucocytolysin upon contact with anti-leucocytolysin. The significance of the listed facts lies primarily in that they establish the existence of a special apparatus consisting of two antagonists (spleen-liver) that regulates the number of white corpuscles in the blood, and secondly—in introducing a substantial correction into previous views on the mechanism of leucocytolysis in the body in various cases, namely that what was previously attributed to the direct effect on white blood cells of various substances _g at present must be interpreted as an effect carried out indirectly—through the spleen, by increasing its leucocytolytic function. Incidentally, a certain relationship between L. and anti-leucocytolysins to anaphylaxis has been established: sensitization turns off the leucocytolytic function of the spleen, while the anti-leucocytolytic function of the liver remains intact, in accordance with which stands the fact of accumulation of anti-leucocytolysins in the blood of sensitized animals and the presence of persistent leucocytosis in them (G. P. Sakharov and O. V. Krasovskaya). This fact may not be without certain significance for understanding the mechanism of anaphylactic shock from the aspect of the intoxication theory. Lit.: Sakharov G. and Zubov S., On some functions of the spleen and on its connection with other endocrine organs, Vestn. endokrinologii, vol. I, No. 6, 1926; Sakharov G. and Krasovskaya O., Leucocytolysins and anti-leucocytolysins in anaphylaxis, Russkaya klinika, 1928, No. 46. See also the literature for the article Leucolysis and chapters on cytotoxins in the main guides cited in the Immunity article.