Warm reactive autoantibodies detected by solid phase technology: Patient characteristics, laboratory features, and clinical significance.

OBJECTIVES: This study focused on the serology, clinical characteristics, and hemolytic potential of warm reactive autoantibodies detected by solid phase red cell adherence.

METHODS: Ninety-seven patients with warm autoantibodies were evaluated. Serologic characteristics included the strength of solid phase reactivity, the results of tube-based ancillary testing, direct antiglobulin test and eluate results, and an assessment for contemporaneous alloantibodies. Clinical characteristics of the patients included age, sex, and primary diagnosis. Each patient was also assessed for evidence of hemolysis.

RESULTS: Most of the 97 study patients were female (63.9%), and the average age was 66 years. Hematologic disorders were the most common diagnosis. A majority (70.1%) of the warm autoantibodies had 3 to 4+ reaction strengths, and approximately 90% had negative testing with at least 1 test tube method. There was an even distribution of direct antiglobulin test reaction strengths, with 74% reactive with anti-immunoglobulin G only. Alloantibodies were identified in 20% of patients. Evidence of hemolysis was identified in only 13 patients (13.4%).

CONCLUSIONS: Warm reactive autoantibodies are more likely to be hemolytic, have strongly reactive indirect and direct antiglobulin tests, remain reactive in tube-based ancillary testing methods, and are seen primarily in patients with hematologic disorders.