Solid‐phase‐only warm reactive autoantibodies: Clinical and laboratory correlations

Background Solid‐phase red cell adherence is a sensitive method for clinically significant alloantibody detection, but this sensitivity is offset by an increased propensity for the detection of apparent non‐specific reactivity and warm‐reactive autoantibodies. Methods The serological and clinical features of warm reactive autoantibodies only identifiable by solid‐phase testing were compared to a subset of warm autoantibodies that required additional tube‐based testing to evaluate for underlying alloantibodies. Results In comparison to warm reactive autoantibodies requiring ancillary testing, solid‐phase‐only warm reactive autoantibodies were more likely to be weakly reactive (IAT and DAT) and were more likely to have DAT reactivity for IgG only. The clinical characteristics of the two groups did not differ significantly with one exception: solid‐phase only warm reactive autoantibodies were only rarely associated with haemolysis (3%) versus the other autoantibodies studied (18%). Conclusions The clinical and serological features of warm reactive autoantibodies can help to predict the haemolytic potential of these antibodies. Laboratories considering the adoption of solid‐phase technology should weigh the benefits of enhanced IgG alloantibody detection against the drawback of increased detection of clinically insignificant warm autoantibodies.