The incidence of red cell alloantibodies underlying panreactive warm autoantibodies

A recognized hazard of administering blood transfusions to patients with panreactive warm autoantibodies is that alloantibodies may be masked. Studies have shown the incidence of underlying alloantibodies to be 30 to 40 percent. Adsorption procedures can be used to remove autoantibodies and allow detection and identification of underlying alloantibodies. This study contains data from 126 patients referred to the Red Cell Immunohaematology laboratory at the National Blood Service, Newcastle upon Tyne, United Kingdom. These patients were from the northeast of England, a population for which data have not previously been reported. Samples identified as containing panreactive warm autoantibodies were subjected to adsorption procedures (95 by alloadsorption and 31 by autoadsorption). Absorbed sera were then tested to identify underlying alloantibodies. Of 126 samples, 39 (31%) contained a total of 61 RBC alloantibodies; 15 (12%) contained 2 or more antibody specificities; and 14 (11%) contained alloantibodies not found within the Rh or Kell blood group systems. Antibodies identified included the following specificities: E (19), D (9), c (7), C (6), S (5), Fy^a (3), Jk^a (2), Jk^b (2), K (2), Kp^a (2), Fy^b, C^w, N, and f (ce). This study reinforces the value of adsorption studies, whether using autologous or allogeneic RBCs, when panreactive warm autoantibodies are present. In addition, this study confirms that it is not appropriate in these cases simply to issue blood which is “least incompatible” or Rh phenotype- and K antigen-matched. Immunohematology2005;21:122–125.