Chronic lymphocytic leukemia (CLL) is one of the most common forms of hemoblastosis. According to a number of specialists, the proportion of CLL in the structure of this pathology is 30–40%. CLL is a benign tumor, the substrate of which is predominantly morphologically mature lymphocytes. The disease is manifested by lymphatic leukocytosis, diffuse lymphocytic proliferation in the bone marrow, enlarged lymph nodes, liver and spleen.

The main manifestations of CLL are caused by the proliferation of mature lymphocytes belonging to a small subpopulation of CD 5+ B lymphocytes. Along with an increase in the number of lymphocytes in the blood, an increase in lymph nodes, liver, spleen, the presence of a large number of autoimmune complications (autoimmune hemolytic anemia and autoimmune thrombocytopenia) is a specific feature of the pathogenesis of this disease. In the overwhelming majority of cases, the B-cell variant of CLL occurs; the T-cell variant of CLL occurs very rarely, in 2–5% of cases. B-cell CLL is traditionally considered a disease of the elderly. Often the disease is benign; over the course of many years, the progression of the tumor process has not been observed even in the absence of primary restraint therapy. But there may be a rapidly progressive course of the disease when death occurs within 1 to 2 years.

CLL is a heterogeneous disease that has many forms with different clinical manifestations, the duration of the disease and the response to therapy. There are several clinical classifications of CLL. Abroad mainly use classifications. These classifications are designed for staging CLL, taking into account tumor progression. In Russia, in the majority of cases, the classification allows for differentiated therapy of hemoblastosis to be distinguished from a benign, progressive (classical), tumor, spleen-night, abdominal, bone marrow, pro-lymphocytic forms. Some authors suggest to distinguish different types of disease in the CLL classification . Therapy for CLL is constantly being improved.

In addition to tumor progression, a significant factor affecting the life expectancy of CLL patients is the development of secondary immunodeficiency, manifested by infectious complications of various localization. The problem of infectious complications in none of the hemoblastoses has such independent and decisive significance as in chronic lymphocytic leukemia. Modern cytostatic therapy allows to significantly control tumor growth in CLL.

At the same time, success in treating patients with this disease is often determined by the possibilities of timely prevention of infectious complications, by the adequacy and timeliness of therapy. Infectious complications in this disease occur in 52 – 86% of patients. In 69.8 – 85% of cases, they are the direct cause of death. The increased susceptibility of such patients to infections is defined by the term “infectivity”. The susceptibility of CLL patients to various infections manifests itself already in the initial stage of the disease. Infectious complications occur even in patients with a benign variant of CLL. As the tumor progression syndrome develops in CLL, the frequency of infectious complications increases.