Clinical relevance of silent red blood cell autoantibodies.

To evaluate the clinical significance of RBC autoantibodies in the absence of clinical signs of autoimmune hemolytic anemia (AHIA), we retrospectively analyzed the clinical course of 60 subjects with silent RBC autoantibodies (IgG, 24; IgM, 35; IgG+IgM, 1) diagnosed and followed at our institute. Asymptomatic RBC autoantibodies were detected in 5 (8.3%) pregnant females, 34 (56.7%) healthy individuals (blood donors, 32; subjects with abnormal agglutination of blood samples, 2) and 21 (35%) patients screened prior to surgery (benign disorders, 16; tumors, 5). In the 5 pregnant females RBC autoantibodies had no effect on the course of pregnancy, the fetus development, or the health of the newborns. No evidence of an underlying disorders was observed in 31 of the remaining 55 (56.36%) subjects, while they were present in 24/55 (43.6%), in 5 /21 cases (23.8%) with IgG autoantibodies and in 19/34 (55.88%) with IgM autoantibodies (p <0.05). The associated disorder was an autoimmune syndrome in 11/55 cases (20%), an HCV- hepatitis in 1/55 (1.8%), and a lymphoproliferative disorder in 7/55(12.7%; marginal cell lymphoma, 1; bone marrow involvement with monoclonal B-lymphocytosis, 6). While IgG autoantibodies disappeared in 10/24cases (41.7%), agglutinins persisted in all cases, with 2/35 (5.7%) subjects who experienced AHIA. These findings indicate that the development of AHIA in subjects with silent RBC autoantibodies is a rare event and that disorders known to be associated with AHIA are present in a relevant proportion of subjects with silent agglutinins.