In the early stages of tumor progression, increased infectivity is associated with defects in the immune response, impaired interaction of T and B lymphocytes, and the development of hypogammaglobulinemia. Immune insufficiency in CLL patients is characterized by a defect in the humoral linkage with symptoms of panhypo immunoglobulinemia, an imbalance of T lymphocytes, characterized by an increase in the number of T suppressors (CD8 + cells) and a decrease in the number of T helper cells (CD4 + cells), impaired phagocytic complementary link; the degree of these changes increases with the development of the disease.

With the progression of CLL, repeated and protracted infectious processes can contribute to their short treatment due to inadequate antibiotic therapy. Cytostatic therapy has a inhibitory effect on the number of T-lymphocytes and neutrophil phagocytic activity. The use of traditional cytostatic treatments (cyclophosphamide, chlorbutin, prednisone) leads to a decrease in the total number of T- and B-lymphocytes.

Among all infectious complications of CLL, the most common inflammatory nonspecific pulmonary-pleural diseases (from 50 to 80% of all infectious complications of CLL) are pneumonia, tracheitis, bronchitis, bronchiolitis, pleurisy.