THE ABDERHALDEN REACTION
Journal of the American Medical Association
During the past year considerable doubt has been cast on the specificity of the Abderhalden reaction. Abderhalden assumes that specific ferments capable of attacking only placental tissue are elaborated as the result of the entrance of placental cells into the general circulation. He used two methods of demonstrating the digestion of the placental tissue by the serum of pregnant women; the first method was by means of the polariscope, and the second, by means of dialyzing membranes. The second
... branes. The second is the one he recommends for clinical purposes. According to this method, the serum and specially prepared placental tissue are introduced into a dialyzing thimble, and the thimble then placed in distilled water. The mixture is placed in the incubator, and the fluid outside the thimble tested the following day for the presence of substances reacting with ninhydrin. The latter substances are supposedly derived from the placental protein as a result of the action of the specific ferments. According to Abderhalden, the greatest precaution must be taken in making the test in order to prevent bacterial contami¬ nations, as the dialysate of the tubes showing bacterial growth will almost invariably give positive ninhydrin reactions. Within the past year, articles have appeared in which the specificity of the reaction has been ques¬ tioned, and others which deny the presence of such specific ferments. In his replies to these articles, Abderhalden states that their results are due to faulty technic, and that his assistants never fail to get positive results with serum from pregnant women and negative results with other serum. If we accept Abderhalden's view, we must assume that specific ferments may be liberated, or generated, as the result of the entrance into the general circulation of any of the cells of the host. If this is so, what prevents the destruction of the remaining cells of the same type? In the views which he has advanced, Abderhalden ignores entirely the antitrypsin normally present in the blood. Possibly he believes that this specific ferment is not subject to antitrypsin influence. Jobling and Petersen found that protein digestion occurs in serums con¬ taining proteolytic ferments if the antitrypsin is removed, and that these substances can be extracted by chloroform and ether, or adsorbed by treating the serum with kaolin, starch and agar. In other words, any agent which will remove the antitrypsin from a serum containing proteolytic ferments can take the place of the placental tissue in the Abderhalden test. This probably explains why Abderhalden reactions may usually be obtained with guinea-pig and rabbit serums, as these serums usually contain ferments. Are there proteolytic ferments present in the serum of pregnant women which will attack only placental protein and which are not present in other individuals, and the action of which is not prevented by the anti¬ trypsin normally present in the serum? To this ques¬ tion I must answer no. During the past year we have examined the serums of a large number of patients entering the hospital suffering from various diseases, and also a number of supposedly healthy individuals. We found that strong proteolytic ferments are rarely present in healthy human beings, but that they are present in large amounts in pregnancy, pneumonia and certain cachexias. We were able to obtain positive Abderhalden reactions in all human serums containing many ferments, regardless of the disease, not only with placental tissue, but also by extracting the serum with chloroform, or by using starch. Positive reac¬ tions were obtained with starch almost as readily as with placental tissue. In each case the serum was tested for its antitryptic strength before and after the tubes were incubated, and always found to be much lower after incubation. In those tests made with nor¬ mal serums, the antitrypsin was also decreased, but the Abderhalden reaction was negative because there were no, or not sufficient, ferments to act on the exposed serum protein. While other substances will give a positive Abderhalden reaction with serum containing proteolytic ferments, placenta appears to be the best agent. It is not clear just why placenta should be the best agent for the adsorption of antitrypsin ; possibly it is because there is a larger area of exposed surface. The ferment of the serum was demonstrated in two ways. First we removed the antitrypsin with chloro¬ form, as recommended by Jobbing and Petersen, and second, added 0.2 per cent, acetic acid to the serum, as recommended by Opie. The serum was then incu¬ bated. The presence of ferments was indicated by digestion of the serum proteins. This was demon¬ strated by observing the increase in non-coagulable nitrogen. We have shown that the placental tissue is not digested, and that it contains as much and often more total nitrogen after digestion with positive serums than before. Further, we have found that such treated placental tissue is more resistant to the action of trypsin than the untreated. This is due to the fact that it has taken up antitrypsin. The greatest care was taken throughout this work to prevent bacterial contaminations, and numerous cultures were made. In no instances was bacterial growth obtained. The thimbles were tested before and after making the tests, and the experiments discarded if subsequent tests cast doubt on their permeability.1 I must conclude, then, as a result of our work, that specific proteolytic ferments capable of attacking only placental tissues do not exist in the serum of pregnant women.