There is not much experimental evidence concerning the effect of various pathological conditions on the agglutination reactions of the blood and serum. It has already been mentioned that there is no proof that the possession of any particular blood group confers upon its owner any special immunity from, or liability to, disease. The numbers, investigated by Alexander in the communication referred to on p. 81, are too small for the observation to be of much value; it is also necessary, as a preliminary to any such research, to demonstrate that there is no abnormal alteration in the reactions of the blood of these patients. It is probable, indeed, that evidence of this alteration in malignant disease already exists, for a reference to it is to be found in Kolmer’s work on serum-therapy,[7] but I have been unable to find a record of the investigation.
I possess, on the other hand, evidence that an alteration may take place in some other diseases, such as pernicious anæmia and familial, or acholuric, jaundice. Evidence for the former was provided recently by a patient whose condition was typical, clinically, of the last stages of the disease. Her corpuscles, tested with stock sera, belonged to Group II, but her serum, tested directly with the corpuscles of prospective donors known to belong to Group IV, agglutinated these vigorously, so that a transfusion could not safely be performed. The same phenomenon has been found by other observers. In acholuric jaundice there is a progressive destruction of red corpuscles in the patient’s circulation. This appears to be connected in some way with an abnormal functioning of the greatly enlarged spleen, since the destruction of corpuscles ceases almost at once when this organ is removed. There seems to be, in addition, an alteration in the blood reactions. In a case which I tested recently, the patient’s corpuscles were quickly agglutinated by serum of Group III, and he therefore nominally belonged to Group II. His serum, however, when separated and tested against other bloods of known groups gave, in addition to a rapid agglutination of corpuscles belonging to Group III, a definite, though slower, agglutination of corpuscles belonging to Groups II and IV, showing that it had acquired abnormal properties.