Background: Autoimmune disorders often develop during the course of B chronic lymphocytic leukemia. The source of the autoantibodies is still uncertain: either uncontrolled production of the malignant B cells or disturbances of the residual normal B and T cells involved in the immune system.
Objectives: To evaluate immunologic parameters in B-CLL[1] associated with autoimmune disorders. As a hypothesis we postulated that in those cases, the malignant B cells might disclose an activated phenotype pattern leading to the production of autoantibodies.
Methods: In the Registry of the Israel Study Group on CLL that includes 964 patients, we found 115 cases showing a single or a complex of autoimmune disorders. We evaluated the lymphocyte morphology, immunoglobulin G and beta-2-microglobulin serum levels and positivity of the CD38 and FMC7 markers, and compared these values with those of a matched CLL population without autoimmune disorder.
Results: The main autoimmune disorders encountered were autoimmune hemolytic anemia (55 patients), Evan's syndrome (n=7), Hashimoto's thyroiditis (n=15), vasculitis (n=5) and rheumatoid arthritis (n=4). We found atypical prolymphocytic morphology in 22%, high expression of the activation antigens CD38 and/or FMC7 in 30%, and high level of immunoglobulin G (> 1000 mg/dl) and beta-2-microglobulin in 57% and 78% respectively. When compared with a matched CLL population without an autoimmune disorder, these values were statistically significant.
Conclusions: Our data, which show activated lymphocyte morphology, high levels of IgG[2] and beta-2-microglobulin, and increased expression of CD38 and/or FMC7 in a significant number of cases, suggest that some degree of activation of B cells may lead to the occurrence of an autoimmune disorder in CLL.