Expression and Clinical Significance of PD-1 and PD-L1 in Pulmonary Carcinoids

The incidence of pulmonary carcinoid (PC) is very rare in primary lung malignant tumors, and the prognosis of this disease is closely associated with its pathological features. In this study, the expressions of programmed death 1 (PD-1) and programmed death ligand-1 (PD-L1) in lung carcinoid cells were detected, and the correlation between the expression and corresponding clinical physiological and pathologic features was further analyzed. The expressions of PD-1 and PD-L1 in 20 cases of PC paraffin-embedded tissue specimens were detected through immunohistochemistry. The H-score of immunohistochemical staining (range, 0-300) was employed to evaluate the expression of PD-1 and PD-L1 in the tumor tissues. In the 20 cases of patients with PC, 40% (8/20) showed positive expressions of PD-1, and 45% (9/20) showed positive expressions of PD-L1. Significantly higher expressions of PD-1 were observed in the smoking patients than in the nonsmoking patients (63.64% vs 11.11%, P