Infectious and autoimmunological complications of chronic lymphocytic leukemia

Abstract

Profound disturbances of different elements of the immune system in chronic lymphocytic leukemia (CLL) lead to impaired elimination of allogeneic antigens, like pathogenic microorganisms, and deficient tolerance of self-antigens, which is responsible for autoimmunological disorders. Susceptibility to infections in CLL patients is due to disease-related immunodeficiency, mainly hypogammaglobulinemia, and aggravated by myelo- and immunosuppressive properties of currently used antileukemic drugs, especially alkylating agents and purine analogues. Severe infections occur in the majority of CLL patients, they may be life-threatening and shortening the patients’ survival. They affect most frequently the respiratory system, and are caused mainly by Gram-positive and Gram-negative bacteria and common viruses like Herpes and Varicella-Zoster. In some patients, especially those treated with purine analogues, opportunistic infections can occur. There are no generally admitted guidelines for the prophylaxis of infections. Vaccinations against influenza and encapsulated bacteria, intravenous immunoglobulins and prophylaxis with cotrimoxazol and antiviral drugs for selected patients under purine analogues or alemtuzumab have been proposed. Autoimmune hemolytic anemia (AIHA) due to the production of anti-erythrocyte autoantibodies is the most common autoimmunological complication of CLL, especially in patients with positive direct antiglobulin test (DAT). It can be also triggered by alkylating agents and purine analogues. The treatment of AIHA includes corticosteroids, rituximab, immunosuppressive agents and splenectomy. Autoimmune thrombocytopenia, pure red cell aplasia, autoimmune neutropenia and non-hematological autoimmune manifestations can also occur.