Systemic IL-17A, IL-22 and IL-27, and Mucosal IgA Responses in Patients with Cutaneous Leishmaniasis: Correlation with Lesion Characteristics and Clinical Phenotypes

This study aimed to quantitatively and dynamically evaluate certain serological and salivary cytological immunological markers and determine their susceptibility to parasite density in patients with cutaneous leishmaniasis. The study included 180 samples, divided between 90 patients and 90 healthy individuals, with patients ranging in age from 5-45 years,during the period from February 2024 to December 2025. Specific immunological markers were measured using a defined technique, and the data were analyzed using one-way analysis of variance (ANOVA), Pearson's correlation coefficient, and other tests.The significant finding of this study is the presence of several statistically significant differences across all indicators based on clinical presentation and lesion site characteristics. However, no statistically significant differences were found based on age (p>0.05). While IL-17A recorded the highest concentration in moist lesions (201.80 pg/mL), IL-22 peaked in ulcerated lesions (134.60 pg/mL), salivary sIgA showed a marked decrease in facial and neck lesions at 88.40 µg/mL. The results also indicated a well-defined linear gradient pattern: at very high parasite density (+4), serum cytokines increased, with IL-17A at 194.50 pg/mL, IL-22 at 124.80 pg/mL, and IL-27 at 264.30 pg/mL, while salivary sIgA decreased linearly to its lowest levels at 85.60 µg/mL. The correlation matrix revealed a strong positive correlation of lesion area with IL-17A (r = 0.642), IL-27 (r = 0.589), and IL-22 (r = 0.518), while it was strongly and negatively inversely correlated with salivary sIgA levels (r = -0.495). This study lays the foundation for the concept of the shared (cutaneous-mucosal) immune axis in cutaneous leishmaniasis, and this opens a new applied horizon for employing secretory salivary immunity as a biomarker to assess disease severity and clinical course.