Abstract
Nowadays, cancer immunotherapy is a promising strategy in solid tumour treatment. It has become a breakthrough in achieving long-term survival in many advanced cases. The essence of modern immunotherapy is to improve the host antitumour immune defence. Currently, it is critically important to determine the biomarkers that could be helpful in planning this type of individual therapy. It has turned out that an important prognostic factor is the evaluation of inflammatory infiltration of the tumour mass, including the characteristics of populations of lymphocytes and macrophages, and the expression of suppressive and regulatory molecules. For lung cancer, <30% of the tumours are resectable and available for a complete microscopic examination. In other cases, the material for the study of inflammatory infiltration may be a tumour biopsy, but this is of limited importance. A valuable way to evaluate the microenvironment of tumour growth is a bronchoalveolar lavage (BAL) fluid examination. In the BAL fluid, the cellular and noncellular components determine the specific type of inflammatory response in an environment of developing cancer. BAL fluid analysis may be a valuable addition to peripheral blood analysis during qualification for modern immunomodulatory therapy. Moreover, it is important material to seek biomarkers of clinical significance.