Abderhalden Reaction

ABDERHALDEN REACTION consists of the detection of so-called "defensive enzymes" (Abwehrfermente), which, according to Abderhalden's theory, are produced by the organism when substances that are not normally found in the blood enter the bloodstream. In Abderhalden's opinion, defensive enzymes are strictly specific, acting only on the substance that caused their appearance, and in this respect, they present a certain analogy to antibodies known from the study of immunity. Abderhalden believes that during the dysfunction of a particular organ, structural elements of the substances that compose it—mainly proteins—enter the blood without having lost the structure specific to that given organ; corresponding enzymes are also produced against them. Thus, by the appearance in the blood of enzymes that break down the tissue of a specific organ, one could conclude that there is a disturbance of its function and establish the localization of the pathological process. This is especially important in diseases with an unclear organic basis, for example, in a number of psychiatric diseases, diseases of the endocrine system, etc. In the case of infection, enzymes may appear that break down the bodies of the corresponding type of microbe, and in the case of malignant neoplasms, those that break down the tissue of the given type of tumor. The Abderhalden reaction gained its greatest significance at one time for the diagnosis of pregnancy. Microscopic particles of the placenta entering the blood in this case could cause the appearance in the blood of enzymes that break down placental proteins. To perform the Abderhalden reaction, specially prepared organ preparations are used as substrates. The main methods for performing the Abderhalden reaction are: 1. Dialysis method. The serum under investigation is placed in a special parchment dialysis thimble, the substrate is added, and the thimble is placed in a vessel with water. In the case of substrate breakdown, the breakdown products penetrate through the thimble into the outer water and are detected there by corresponding tests (biuret or ninhydrin). Instead of dialysis, one can, after a certain time, precipitate all proteins and determine the breakdown products remaining in the solution. 2. Optical methods are based on the change in the rotation of the plane of polarization (polarimetry) or the refractive index (refractometry and interferometry) of the mixture of serum and substrate in the case of the breakdown of the latter and the appearance of low-molecular-weight compounds in the solution. Recently, a number of further modifications of the Abderhalden reaction have appeared, in which the breakdown of protein by serum is detected either by a change in the specific gravity of the reaction mixture (Krasnushkin) or by the appearance of decay products not precipitable by strong alcohol (Luttge-Mertz). This reaction, proposed by Abderhalden in 1910, initially aroused great interest, but at the present time, it has almost completely lost its significance, as it requires exceptional care in execution and, even with the observance of all precautions, often gives demonstrably incorrect results (e.g., a positive reaction for pregnancy in men). A number of recent works generally deny the very fact of the appearance of specific defensive enzymes in the blood. Lit.: Freyfeld E., Defensive Enzymes, Moscow, 1921; Abderhalden E., Die Abderhalden'sche Reaktion, Berlin, 1922; Oppenheimer C., Die Fermente und ihre Wirkungen, p. 1078, Leipzig, 1926.