DANISHA PHENOMENON (J. Danysz, the Polish pathologist working in Paris, 1860 — 1928) — change of toxicity of equivalent mix of toxin with antitoxin depending on an order of addition of toxin to antitoxin. D.'s studying f. matters for improvement of the existing methods of titration anatoxins (see) on binding of antitoxin as at the same time the high percent of the mistakes caused by D. f can take place.
In 1902 Danish established that if to add equivalent amount of toxin to antitoxin it is single-step, then the received mix will be non-toxic. If to add the same amount of toxin to antitoxin in parts through certain time slices, then the formed mix is toxic. This phenomenon was originally described for mixes of ricin and anti-ricin, diphtheritic toxin and the corresponding antitoxin, and afterwards is confirmed in experiences with various antigens and antibodies. Danish explained the found phenomenon with the fact that toxin and antitoxin are capable to connect among themselves in various quantitative ratios.
This look contradicted P. Ehrlich's representations, according to the Crimea toxin connects to antitoxin always in definite proportions as chemical reaction between to - that and alkali. Board regarded D. f. as confirmation of the adsorptive theory. He believed that reaction antigen — an antibody submits to patterns of processes of adsorption at which the reacting substances can connect with each other in different proportions. The obtained data on structure of antigens and antibodies allow to explain the mechanism D. f. Immunochemical, studying of antigens and antibodies showed that the majority of natural antigens (see) several determinant groups, and a molecule of an antibody depending on belonging to this or that class have immunoglobulins (see) has from two up to ten antigensvyazyvayushchy centers — an anti-determinant. Owing to this antibody and antigens can form complexes with various molar ratio of reagents (see. Antigen antibody reaction ). The similar phenomenon takes place and at interaction of toxin with antitoxin. Most effectively neutralization is reached at formation of the large units consisting of several molecules of toxin connected among themselves by bridges of molecules of antitoxin. This phenomenon arises at an equivalent ratio of reagents and is observed at single-step mixing of toxin with limited amount of antitoxin. In case of fractional addition of toxin to a certain amount of antitoxin a significant amount of molecules of antitoxin is spent originally for neutralization of separate molecules of toxin since at relative excess of antitoxin the last is not capable to aggregate effectively toksinony the Arising cell-bound immune complexes consist at the same time of molecules of toxin to which surface one or two anti-determinants attached molecules of antitoxin. At addition to similar complexes of new portions of toxin formation of large units becomes impossible that significantly reduces efficiency of neutralization of toxin. Use for neutralization of toxin of the monovalent fragments of antitoxin received at its proteolytic splitting confirms this explanation of D. f. During the use of Fab-fragments of antitetanic antitoxin distinctions in protective action of these fragments are not observed both at single-step, and at fractional addition of toxin. It occurs because monovalent fragments of antitoxin are incapable to form intermolecular bridges and to create cell-bound immune complexes, large by the size. G. N. Kryzhanovsky, etc. in 1972 showed that neutralization of toxin requires significantly bigger molar surplus of monovalent fragments of antitoxin in comparison with amount of not split antitoxin.
See also Toxin-antitoxin reaction .
Bibliography: Kryzhanovsky G. N., etc. Some features of toksinneytralizuyushchy action antistolbnyachno-go immunoglobulin and its fragments, Bulletin Ekspery, biol, and medical, t. 74, No. 8, page 66, 1972, bibliogr.; To e about t E. A. and Meyer M. M. Experimental immunochemistry, the lane with English, M., 1968, bibliogr.; Mikhaylo in I. F. and Stefani D. V. About the mechanism of a phenomenon of Danish, Zhurn, mikr., epid, and immun., No. 8, page 29, 197C; D a n at s z J. Contribution a l’etude des of propri£t£s et de la nature des melanges des toxines avec leurs antitoxines, Ann. Inst. Pasteur, t. 16, p. 331, 1902.
A. V. Ponomarev, A. Ya. Kulberg.