Serological and immunoglobulin studies in autoimmune haemolytic anaemia with emphasis on the nature of biphasic antibodies.

55 cases of autoimmune haemolytic anaemia with positive direct Coombs' test were investigated for the nature of autoantibodies. The studies involved characterization of the autoantibodies on the basis of their thermal amplitude, serological specificity, nature of immunoglobulin and light chain specificity. The findings showed that the autoantibodies could be classified as cold autoantibody (18 cases), warm autoantibody (5 cases) and biphasic autoantibody which reacted at 37 degrees C as well as at 6 degrees C (32 cases). Further classification of these cases was made on the basis of antibody specificity to blood groups, immunoglobulin type in relation to the optimum temperature of their reaction.