Development of ‘auto‐anti‐A1 antibodies’ following alloimmunization in an A2 recipient

In the majority of cases Al antibodies fail to react at 3 7°C and are of no clinical significance. Haemolytic transfusion reactions due to A1 antibodies active at 37OC are extremely rare (see Mollison, 1983). In most cases the immunoglobulin class of the antibody has been shown to be IgM. Only one case of a delayed haemolytic transfusion reaction due to IgM and IgG anti-A1 in an A2B patient has been reported by Lundberg & McGinniss (1975). Cold reacting auto anti-A or anti-Al IgM, usually of no clinical significance, have been found occasionally. However, only two well-documented cases of autoimmune haemolytic anaemia due to anti-A autoantibodies have been published (Szymanski et al, 1976; Parker et al, 19 78). In the first case the autoantibody is likely to have been IgG or a mixture of IgM and IgG whilst in the latter case it was probably pure IgM. We here report a severe delayed haemolytic transfusion reaction in an A2 patient who was transplanted with a kidney from a group 0 donor and at about the same time was transfused with 3 units of A1 blood. Anti-A1 developed about 1 week after and at this time the direct antiglobulin test (DAGT) became positive and remained so long after the transfused A1 red cells had been eliminated.