The most striking findings of this study are: the difference of the proportion of PD-1 and CTLA-4 positive cells in the BALF when compared with the peripheral blood in the same patient and the elevated proportions of activated CD8+ cells with PD-1 and CTLA-4 molecules in the BALF from the cancer environment, especially in squamous cell carcinoma. The gene discussed is CTLA4; the disease is cancer.