In the Paris population of blood donors with normal B phenotype, two groups can be formed owing to their respective serum a-D-galactosyltransferase activity and red cell aggiutinability with an anti-B antibody. Both parameters are closely correlated. The aggiutinability groups partially overlap. In an African population from various ethnical origins, this correlation was observed only in some individuals. 11 among 20 subjects belonged to a third group defined by a high transferase activity. The third group with the strongest agglutinability previously described by Gibbs et al. [6] were not encountered. On the other hand, serum transferase activity varied inversely as agglutination scores with anti- Hi (Ulex). Both parameters are closely correlated but not in the same way in Caucasian as in African individuals. In the latter, this relation does not depend on the aggiutinability group. The H antigen strength variability, according to ethnical origins, may explain these results.

43 adults from a renal dialysis unit staff have received regularly spaced γ-globulin administrations for hepatitis B prophylaxis. Several blood samples were collected over a prolonged period of time (160 days). Following γ-globulin administration, anti-immunoglobulin antibodies of the IgE class were detected in 80% of this population, a fortnight after the first injection using serum absorptions on polymerized γ-globulins or a specific inverse RAST method. The reactivity pattern of these IgE anti-immunoglobulin antibodies was similar to that observed for the anti-immunoglobulin antibodies with ‘limited specificity’ detected by passive hemagglutination, in that they reacted with only one of the immunoglobulins of the panel used for their detection. A decrease of the overall IgE levels was observed in 62% of the subjects for a prolonged period of time following γ-globulin administration. This suggests a feedback regulation mechanism for the reagin production in man, as it has already been observed in animals. A high incidence of anti-immunoglobulin antibodies of various classes was observed in this study. However, only a small number (4/43) of adverse reactions appeared following γ-globulin administration. For some of these subjects, the presence of specific IgE anti-immunoglobulin, detected by the inverse-RAST technique, suggests a possible role of such antibodies in some intolerance reactions to γ-globulin administration.

The AutoAnalyzer was used for quantitative measurements of antibody agglutinating activity by a Polybrene agglutination technique. Since the continuous flow system introduces an experimental error to the determination of true agglutination percentage, it is necessary to apply a correction factor. The experimental method of correction is described.

Some cold autoantibodies found in acquired hemolytic anemias react with both the A, B or H, and the I, blood group antigens. The agglutinating activity of such an autoantibody of the IgM type was studied by a quantitative method in an AB patient. This antibody agglutinated neither A, B and O red blood cells in the absence of the 1 antigen, nor the Bombay red cells. It agglutinated equally AI + and BI + red cells, and weakly the OI+ red cells. Both agglutinating activities towards the AI+ and BI+ red cells were observed to decrease simultaneously and partially upon absorption on OI + red cells, at 4°C. They disappeared simultaneously and completely upon absorption on either AI + or BI + red cells. The antibody absorbed on, and eluted from AI + red cells showed a similar agglutinating activity towards the AI + and the BI + red cells ; likewise, when it was absorbed on, and eluted from BI + red cells. The study of the antibody-agglutinating activity and of its 7S subunit activity, as well as of the inhibitory activity of the Fab fragments, led to the conclusion that the observed results were due neither to a mixture of antibodies, nor to an anti-I or an anti-HI antibody, but to a cross-reactivity between the A, B and I antigens. The antibody recognized a determinant which comprises I and some part shared by A and B. It can be named anti-I (A + B).