Clinical value of CD97 and CD55 levels in the differential diagnosis of tuberculous and malignant pleural effusions

This study evaluated the clinical levels of CD97 and CD55 for the differential diagnosis of pleural effusion. Pleural effusion samples were collected from 106 patients (55 tuberculous pleural effusions [TPE] and 51 malignant pleural effusions [MPE]). CD97 and CD55 levels in pleural effusions were measured by enzyme-linked immunosorbent assay. CD97 levels were significantly higher in the TPE group than in the MPE group (P < .001), while CD55 levels in the MPE group were significantly higher than the TPE group (P < .001). The sensitivity and specificity of CD97 testing for the differential diagnosis of TPE and MPE was 80.0% and 60.8%, respectively, while the sensitivity and specificity of CD55 testing for TPE and MPE was 88.2% and 85.5%, respectively. Furthermore, the sensitivity and specificity of combinatorial CD97 and CD55 testing for TPE and MPE was 90.0% and 87.5%, respectively. Moreover, CD97 and CD55 were negatively correlated in the MPE group (r = –0.383, P = .005), while no correlations were observed in the TPE group. CD97 or CD55 showed no correlations with other inflammatory cytokines (tumor necrosis factor α, interleukin 1β, erythrocyte sedimentation rate, and C-reactive protein) in both groups (P > .05). CD97 and CD55 may be used as biological markers for the differential diagnosis of pleural effusion in clinical settings.