Autoimmune disease and chronic lymphocytic leukemia: autoimmune hemolytic anemia, pure red cell aplasia, and autoimmune thrombocytopenia.
Immune dysregulation, a hallmark of chronic lymphocytic leukemia (CLL), manifests itself in three autoimmune diseases: warm autoimmune hemolytic anemia (AIHA); idiopathic thrombocytopenia (ITP); and, pure red cell aplasia (PRCA). AIHA occurs in 11% of advanced stage CLL patients. Prednisone is the first treatment of choice, with 90% responses and 65% complete responses. More than 60% of patients relapse when treatment is stopped. Intravenous immunoglobulin, the next line of treatment, causes responses in 40% of patients. While the data are very limited, cyclosporine A is a reasonable choice for third-line therapy. Alkylating agents, danazol, plasma exchange, immunoabsorption, vincristine-loaded platelets, splenectomy, and splenic irradiation are also reported to cause responses. The data on mechanisms of AIHA are most consistent with immune dysregulation leading to loss of tolerance to a self antigen which in turn leads to the immune-based hemolytic anemia. PRCA is underrecognized in CLL with 6% of CLL patients having PRCA when tested for it. Unlike AIHA, PRCA often occurs in early stage disease. Anemia, reticulocytopenia, and a marrow virtually devoid of red blood cell precursors are hallmarks of PRCA. Corticosteroid therapy is the first line of treatment. If a response is not obtained in 4 weeks, cyclosporine A should be added. Although the data on pathophysiology are very limited, PRCA appears to be the result of an abnormal T cell that both fails in its normal function to support growth and inhibits the growth of erythroid progenitor cells. ITP occurs in 2-3% of CLL patients, occurs in early stage disease and may be a presenting manifestation. Initial therapy for ITP mirrors the guidelines for primary ITP. Initial therapy should consist of prednisone. Seventy percent of patients respond. Splenectomy is a reasonable second-line treatment. Autoimmune phenomena, largely related to blood cells, are based in the immune dysregulation of CLL. Longer survivals in CLL patients, more treatment regimens per patient, and more immunosuppression with modern treatments, allow us to predict an increasing incidence of autoimmune blood cell diseases in CLL.
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