The significance of protein SP70 detection for differentiating benign and malignant pleural effusion

Objective To investigate the diagnostic value of detection of protein SP70 in differentiating benign and malignant pleural effusion. Methods A case-control study was conducted from July 2011 to February 2012. 108 cases of pleural effusion from patients with clinically proven lung cancers and 122 cases of benign pleural effusion were collected.SP70 was detected by Sandwich ELISA，while CEA，CYFRA21-1，NSE were measured by electrochemiluminescence immunoassay for comparison.Meanwhile，protein SP70 on exfoliated cells in pleural effusion was detected by direct immunofluorescence， and was compared with the results of HE staining.The differences between the groups were evaluated by the chi-square test Fisher′s exact test. Results Positive rates of SP70，CEA，CYFRA21-1，NSE were 72.2%，58.3%，52.8% and 30.6% in malignant pleural effusion，obviously higher than benign pleural effusio(9.8%，13.1%，23.0% and 19.7%).The specificity of SP70，CEA，CYFRA21-1，NSE were 90.2%，86.9%，77.0% and 80.3%，NSCLC had significantly higher positive rate than SCLC（74.3%>0.0%，P=0.02<0.05）， detection of protein SP70 in malignant pleural effusion had significantly higher coincidence rate than HE staining（72.2% vs 47.2%， χ2 =14.03，P<0.05）. Conclusion Determination of the protein SP70 in pleural effusion and in exfoliated cells，can improve the sensitivity and specificity of the diagnosis of malignant pleural effusion.（Chin J Lab Med，2012,35：1150-1154） Key words: Enzyme linked immunosorbent assay; Fluoroimmunoassay; Pleural effusion; Tumor markers，biological