Prognostic value of soluble H7-B4 in pleural effusion associated with lung cancer.

B7-H4, a member of the inhibitory B7 family, can restrain T cell proliferation, activation, and cytokine secretion and may be involved in immune evasion in cancer patients. This study aimed to evaluate the diagnostic and prognostic value of pleural effusion levels of soluble B7-H4 (sB7-H4) in lung cancer patients with malignant pleural effusion (MPE). Pleural effusion samples were collected from 98 lung cancer patients with malignant effusion and from 60 patients with nonmalignant pleural effusion. Pleural effusion concentrations of sB7-H4 were measured using sandwich enzyme-linked immunosorbent assay. Malignant effusion exhibited higher sB7-H4 levels than those in nonmalignant effusion (P < 0.01). Lung cancer patients with pleural effusion sB7-H4 levels below 35.8 ng/ml had a longer overall survival than those with higher levels (P < 0.05). By multivariate analysis, pleural effusion sB7-H4 was an independent prognostic factor in patients with MPE. In conclusion, measurement of sB7-H4 might be a useful diagnostic and prognostic value for MPE patients.