[A preliminary study on clinical diagnostic value of plasma elafin in skin acute graft-versus-host disease].

Objective: To analyze the specificity, sensitivity and receiver operating characteristic (ROC) curve of plasma elafin for diagnosis of skin acute graft-versus-host disease (aGVHD), and to explore its clinical diagnostic value.

Methods: Incidence of skin aGVHD from fifty-three patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT) were observed prospectively in Guangdong General Hospital from Apr 2010 to Aug 2011. The plasma concentrations of elafin were detected by enzyme-linked immunosorbent assay (ELISA). Skin biopsies were taken from 28 patients with skin rash, and elafin expression in the skin was detected by immunohistochemistry. Positive expression was defined as significant staining of at 50% of the depth of the epidermis, excluding the granular cell layer and the acrosyringium.

Results: Among 28 patients with skin rash, twenty-five were considered as skin aGVHD by clinical diagnosis, seventeen were confirmed as skin aGVHD by pathological biopsy. 11 cases were elafin positive by immunohistochemical staining. Elafin protein was overexpressed in aGVHD skin tissue (P = 0.001). Plasma concentrations of elafin were significantly higher in patients with skin aGVHD (positive) group than in those without skin aGVHD (negative) group (P = 0.005), among which there being no statistically significant difference in plasma elafin level between patients with grade I skin aGVHD group and negative group(P = 0.971), but being statistically significant difference compared patients with grade II-IV skin aGVHD group with those with grade I skin aGVHD group (P = 0.02) and with negative group (P = 0.008). Using the pathological diagnosis as the gold standard, the estimated specificity and the sensitivity of clinical diagnosis criteria were 27.3% and 100%, respectively, and those of tissue elafin protein level were 100% and 64.7%, respectively. The area under the ROC curve was 0.909 (0.797 - 1.021) when plasma concentrations of elafin was used in diagnosis of skin aGVHD. The sensitivity was 82.4% and the specificity was 81.8 % when the critical value was set at 1456.043 µg/L.

Conclusion: Plasma concentration of elafin is significantly higher at the onset of skin aGVHD. It can be used as biochemical marker of skin aGVHD and has higher value in diagnosis of skin aGVHD.