Increased expression of interleukin-17A in the lesional skin indicates increase of serum antibody anti-phenolic glycolipid-I in leprosy patients

Abstract

Background: In lepromatous type of leprosy, the serum titer of the antibody against phenolic glycolipid (PGL)-I-a-specific antigen in leprosy that is produced by B cell is high. Whereas, the interleukin (IL)-17A expressed by T-helper 17 cells could induce B-cell differentiation. The role of IL-17A in leprosy is still unknown. Hence, this study aimed to assess a correlation between IL-17A expression in the lesional skin and anti-PGL-I immunoglobulin (Ig) M serum levels in leprosy patients. Methods: This study was performed in Leprosy Clinic, Dr. Hasan Sadikin Hospital Bandung, Indonesia, using a cross-sectional analytical study. A punch biopsy obtained from 49 leprosy patients was included through consecutive sampling for measurement of IL-17A expression in the skin by immunohistochemistry scoring (histoscore). Furthermore, the anti-PGL-I IgM level in serum is evaluated by enzyme-linked immunosorbent assay. Results: The IL-17A expressions in the skin biopsies of tuberculoid (TT), borderline tuberculoid (BT), mid-borderline (BB), borderline lepromatous (BL), and lepromatous leprosy (LL) patients using histoscore were 1.00, 2.31, 4.63, 5.06, and 10.14, respectively, and they showed significant differences ( P = 0.0001). The titer of anti-PGL-I IgM levels was 89 pg/ml, 555 pg/ml, 1.244 pg/ml, 1.920 pg/ml, and 23.591 pg/ml in TT, BT, BB, BL, and LL patients, respectively, and they showed significant differences ( P = 0.005). The results of Rank–Spearman correlation analysis between IL-17A expression in the skin and anti-PGL-I IgM serum levels were as follows: r = 0.767 and P = 0.0001. Conclusion: These results suggested that the increase of IL-17A expression in the lesional skin indicates the increase of anti-PGL-I IgM serum levels in leprosy.