Bordet-Gengou Reaction

BORDE-GENGOU REACTION (Bordet-Gengou), fixation of alexin (complement fixation reaction according to Ehrlich), discovered by the authors in 1901. The reaction is based on the fact that an antigen (microbe, foreign protein, etc.), combining with the corresponding immune serum, previously inactivated by heating for half an hour at 56°, forms with it a complex that greedily absorbs (adsorbs) alexin (see Antigens, Alexin). As alexin (Ehrlich's complement) for the Bordet-Gengou reaction, fresh normal sera of various animals are used, most often guinea pigs. The Bordet-Gengou reaction proceeds in two stages. Its course can be represented by the following example: the first system-cholera vibrio (antigen) + anti-cholera inactivated serum-heated-forms a complex capable of greedily adsorbing alexin; the second system-sheep erythrocytes (antigen) + immune rabbit hemolytic serum inactivated by heating-also forms a complex capable of greedily adsorbing alexin, with which here occurs the dissolution of erythrocytes-hemolysis. If alexin is first mixed with the first system, it will completely adsorb it; obviously, the second hemolytic system added afterward, finding no free alexin, will not give a hemolysis reaction. This will be a case of positive Bordet-Gengou reaction, when there is no hemolysis due to the absence of free alexin. If in the experiment the first system consists of antigen and immune serum that do not correspond to each other (for example, cholera vibrio + anti-typhoid serum), then no complex adsorbing alexin is formed between them, and the latter, remaining free, will then join the second hemolytic system, as a result of which the dissolution of sheep erythrocytes will occur. This will be a case of negative Bordet-Gengou reaction. From what has been said, it is clear that when setting up the Bordet-Gengou reaction, it is necessary to observe strict sequence in mixing the ingredients, namely, to prepare the first system first, add alexin to it and leave this mixture for 1/4-1 hour at 37°, to give time for the alexin adsorption reaction to complete, and only after that add the second hemolytic system, which serves as an indicator of whether alexin has been adsorbed, i.e., whether the antigen and immune serum correspond to each other in the first system or not. The Bordet-Gengou reaction allows solving problems in two directions: 1. Having immune sera to various antigens at one's disposal, one can accurately determine the nature of an unknown antigen: microbe cultures, foreign protein, etc. The culture being tested or foreign protein will obviously give a positive Bordet-Gengou reaction only with immune sera corresponding to their nature (e.g., protein from a human bloodstain-with immune serum against human protein, and not against horse, cow, pig protein, etc.). 2. Having known antigens at one's disposal (microbe cultures, protein preparations, etc.), one can determine the origin of the unknown serum being tested. Thus, serum from a typhoid patient or convalescent will give a positive Bordet-Gengou reaction not with cholera, not with dysentery, etc., but only with typhoid culture, and conversely, serum from a cholera or dysentery patient-only with the corresponding microbe cultures, and not with typhoid microbe culture. The Bordet-Gengou reaction has wide application not only in microbiology, but also in hygiene (Schutze) and in forensic medicine (Neisser, Sachs, Brack). In addition, taking into account the quantitative aspect of the reaction, one can use it to study some general biological problems, e.g., the question of the relationship between different species of monkeys, different races of people (Bruk, Neisser), etc. - For details on the nature and mechanism of the Bordet-Gengou reaction, see Immunity.

The numerous works of B., many of which have become classical, were published mainly in the "Annales de l'Institut Pasteur". B. gave complete theoretical completion to his views in the field of immunity in the form of a special monograph-"Traite de l'immunite".