Specificity of Acquired Haemolytic Anaemia Autoantibodies and their Scrological Characteristics

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Abstract
Summary In a study of 24 red cell eluates obtained from patients with acquired haemolytic anaemia of the ‘warm’ type, it was established that some eluates possessed autoantibody of only one specificity either for ‘normal’ (‘anti‐nl’) or ‘Rhnull’ (‘anti‐dl’) red cells, whereas others contained autoantibodies of both specificities. Combined autoantibodies were often better recognized by different testing procedures than by the same method. Thus the ability of these autoantibodies to strongly sensitize ‘normal’ red cells by the ficin test and ‘Rhnull’ cells by the antiglobulin test was frequently found, whereas the occurrence of strong ficin‐reactive ‘anti‐nl’ and strong ficin‐reactive ‘anti‐dl’ was rare.Additional studies using red cell eluates revealed that no direct correlation could be established between the presence of complement components and the intensity of the indirect antiglobulin test using anti‐IgG serum. On the other hand, the simultaneous presence of ‘anti‐nl’ and ‘anti‐dl’ autoantibodies was often associated with the presence of complement components in the red cell eluates. Fixation of complements by Rh isoantibodies of multiple specificity has been reported, and thus the presence of complement components in association with ‘anti‐nl’ and ‘anti‐dl’ may be analogous to complement fixation by multiple Rh isoantibodies. The formation of ‘anti‐nl’ with ‘anti‐dl’ which tends to result in complement components being fixed by the antibody may be considered as a natural progression of antibody synthesis associated with an advanced state of autoimmunization.