Lysins

Lysins, substances secreted by animal and plant cells, to which is attributed the ability to dissolve various foreign cells. This term was first and almost simultaneously applied by Ehrlich and Gamaleya. Ehrlich called bacteriolysins the substances secreted by bacteria that dissolve red blood cells (theta-lysin, staphylocysin, etc.); these substances are now called hemolysins and hemotoxins. Gamaleya, however, designated the word "bacteriolysins" for substances that dissolve bacteria themselves; this latter meaning has been retained in science. At the same time, the terms "lysis" as a process and "lysins" as agents of this process began to be applied to all phenomena of melting and destruction of tissues (see Autolysis, Histolysis) (spermatolysins, nephrolysins, etc.), bacteria, toxins (toxolysins), and chemical substances (albuminolysis, glycolysis, etc.). But these various processes are not the same in their mechanism and in their producing agents - the lysins. The processes that cause the least doubt are those in which complex organic substances are split; they belong to the extensive class of phenomena of enzymatic, predominantly hydrolytic, character. These include proteolysis, glycolysis, lipolysis, etc. The same enzymes (endolysins) probably also produce postmortem melting of organs - autolysis and heterolysis. As for the damage to living tissues and cells caused by specific immune sera containing, for example, spermatolysins and spermatotoxins, nephrolysins and toxins, neuro-, hepatolysins and toxins, the mechanism of their action is less clear. In these processes, no actual dissolution of cells is observed. Thus, spermatolysin causes only immobility of the seminal elements. The classical and best-studied representatives of this lysis - hemolysins - by no means dissolve red blood cells. They only convert hemoglobin into solution, leaving the red blood cells rather in the form of a condensed stroma. Thus, in applying to this group of properties, the term "cytotoxins" is more appropriate than "cytolysins." Actual dissolution - lysis - is undergone by bacteria under the influence of bacteriolysins. This has been established for cholera and other vibrios in the so-called Pfeiffer phenomenon in the peritoneum of guinea pigs, as well as in Bordet's experiment in vitro. It has been established that for such lysis it is necessary to have two components, namely: a specific antibody (see) and complement (see). However, most other bacteria are not subjected to dissolution under such conditions; they are killed. Thus, instead of bacteriolysins, bacteriocidins are discovered, i.e., substances that kill bacteria. However, according to the latest research, this bacteriocidal action should also be questioned. These researches relate to the so-called virucidal ability of blood serum with respect to the smallpox virus and others. The blood serum of vaccinated individuals, as is known, can neutralize and inactivate the vaccine virus. It was assumed that it dies in the process. It turned out that from this neutral mixture the virus can be obtained by dilution. It has also been proven (Olitzky and colleagues) that the vaccine virus and poliomyelitis viruses do not die in immune organisms, although they do not reveal their presence until separated from the serum by cataphoresis. Thus, in many cases, the action of L. on microbes is reduced not to dissolution and not to killing, but only to their binding and bringing into an inactive state. This conclusion fully coincides with the general concept of the action of antibodies (see) on microbes, according to which the latter are bound by the former (agglutination, see). As for the second component of L. - complement, the mechanism of its action is not yet explainable. Many researchers consider it an enzyme, but cannot determine to which class of enzymes it belongs. It does not have proteolytic and apparently generally hydrolytic action. Perhaps it participates in the oxidolysis of bacteria. - In any case, it is obvious that the chapter on L. in immunology requires a thorough review and development. It should be added that agents that dissolve bacteria and differ in their properties from blood L. have also been found in tears (lysozyme, see), tissues and egg white, as well as in the bacteria themselves (Gamaleya's bacteriolysins, bacteriophages, endolysins, cytolyins).