Structural components and immunohistochemical features of the respiratory organs in children with bronchiectasis

The study of chronic inflammation of lung tissue in bronchiectasis in children is necessary for a deeper understanding of the cellular and molecular mechanisms of chronic respiratory diseases and the development of new approaches to their treatment. The aim of the study was to investigate histological and immunohistochemical changes in the structures of the bronchi and lungs in bronchiectasis in children. The study used lobes or fragments of lungs removed during surgery for bronchiectasis in 62 children. The obtained micro-preparations of bronchial and lung tissue were stained with haematoxylin and eosin, picrofuchsin according to Van Gieson, and resorcinol fuchsin according to Weigert. Immunohistochemical studies of lung micro-preparations were performed using monoclonal antibodies to Ki-67, Bcl-2, CD3, and CD20. Comparing the results of immunohistochemical studies in children with bronchiectasis and in the control group, significant differences can be noted. Thus, the level of CD3+ cells, a marker of immune activity, is significantly higher in children with bronchiectasis in all age groups compared to control indicators (p<0.001) and continues to increase with age. Similarly, the content of CD20+ cells is also higher in children with bronchiectasis regardless of age (p<0.05 and p<0.01), with a tendency for their number to increase with age. The Bcl-2 indicator, associated with cell apoptosis processes, is slightly elevated in children with bronchiectasis, but the differences are not always statistically significant. At the same time, the Ki-67 level, which reflects the intensity of cell proliferation, is significantly higher in children with bronchiectasis in all age groups compared to the control group (p<0.001). Thus, children with bronchiectasis show changes in immunohistochemical characteristics, indicating activation of the immune system and increased cell proliferation. These processes may be associated with inflammation and immune responses typical of this disease. Consequently, it can be concluded that all links of the immune system are activated in children with bronchiectasis. At the same time, it has been established that destructive changes in immune components prevail in children with bronchiectasis, which indicates a decrease in their protective function.