Isoagglutinin test

These specific substances or blood group factors are detected by their property of inhibiting agglutinin reactions between human erythrocytes and heterologous human sera. This is the so-called isoagglutinin test which can detect the factors in dilutions of more than 1 part in 10 million. An even more sensitive but less specific test is their power to inhibit hemolysis of sheep s erythrocytes by the serum of rabbits immunized with certain human corpuscles. 

The serum immunoglobulin pattern has been constant in these cases, and isoagglutinins were absent in four of the boys. The responses to oral poliomyelitis vaccine have been poor Since this oral vaccine usually evokes IgA antibodies, this suggests that the patients IgA may be largely inert. Subnormal responses to diphtheria and TAB are recorded. Lymphocyte transformation to PHA and delayed hypersensitivity were normal where tested. The tonsils, adenoids, thymus, and spleen were normal except in one case with lymphopenia, where tomography did not reveal any thymus, and tonsils, adenoids, and lymph nodes could not be detected (SI). The prognosis seems similar to that for Bruton s disease. 

The assay of isoagglutinin activity proved to raise considerable difficulties, for the techniques employed in different laboratories were so different in detail that the results were not quantitatively comparable, and the red cells used to observe the agglutination reaction inevitably varied somewhat from one individual donor to another. To eliminate these complications, Reference Standard preparations of anti-A and anti-B agglutinins were made up from certain preparations of Fraction III-l, and distributed to all investigators testing new preparations. By assay of the activity of a new preparation against the reference standard, studying both at a series of dilutions, the relative activity of different preparations could be reliably estimated (50). 

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