A girl, A. Sl., aged 2 years 6 months, was admitted to the paediatric clinic with vascular thrombocytopathy, and some difficulty was experienced in determining her ABO group, as her cells were grouped as AB, while her serum contained agglutinins active against normal B cells. The child had never previously been transfused.Red cell investigations, carried out in the Department of Serology of the Institute of Haematology yielded the following results :Group A,B, Rh phenotype CcDee, MS, PI+, Kell-, Fya-, Jka+ Cold type anti-B agglutinins, inactive against the patient's own cells, were found in the serum.Blood specimens from the mother and sister of the propositus were then examined, and it was established that both were of group A,B, with anti-A, with anti-B agglutinins present in their serum. The results of further investigation of the blood group antigens were as follows:Mother of the propositus: Group A,B, Rh phenotype CcDee, MNS, P,+, Kell-, Fya-, Jka -.Sister of the propositus: Group AzB, Rh phenotype CcDee, MNS, PI +, Kell-, Fya-, JKa+.The results of a detailed serological investigation of the three individuals, which proved to be very similar, are given below. As the findings revealed certain apparently familial atypical properties of the B antigen, we have called it Bsl.
Tests on Red CellsRed cells from the three A,Bsl individuals were tested with a large variety of sera from individual donors (67 anti-B sera, 36 anti-A sera,