In our study, we show for the first time the differential expression of check-point molecules: PD-1 and CTLA-4 on CD8+ and CD4+ cells at the various stages of maturation and differentiation in the lung cancer microenviroment, e.g., bronchoalveolar lavage fluid (BALF) harvested form the tumor proximity. The gene discussed is PDCD1; the disease is lung cancer.