Assessment of Serum and Saliva CRP, IL-17, and IL-19 Levels in Patients with Different Severity of Acne Vulgaris

Acne vulgaris (AV) is a chronic inflammatory skin disorder, and cytokines such as interleukin-17 (IL-17), interleukin-19 (IL-19), and C-reactive protein (CRP) are thought to contribute to its immunopathogenesis. This study investigated serum and salivary levels of CRP, IL-17, and IL-19 in patients with AV and examined their relationship with disease severity. A total of 99 participants aged 15-30 years were classified into Control (n = 28), Moderate AV (n = 43), and Severe AV (n = 28) groups using the Global Evaluation Acne (GEA) Scale. Serum and saliva samples were analyzed using ELISA and immunoturbidimetric assays. Statistical comparisons and correlation analyses were performed. Serum IL-17 levels were significantly higher in the control group compared to both acne groups (<i>p</i> < 0.05), with no gender-related differences. Salivary cytokine levels showed no significant group differences. However, IL-17 and IL-19 were strongly correlated in both saliva (r = 0.672, <i>p</i> < 0.005) and serum (r = 0.538, <i>p</i> < 0.005) across the entire study population. Serum and salivary CRP levels showed no significant differences between groups. In contrast to previous reports, our study found lower serum IL-17 levels in AV patients compared to healthy controls, challenging the assumption of its purely pro-inflammatory role and suggesting a potential compensatory or regulatory immune mechanism to maintain homeostasis. These findings may also reflect distinct physiological pathways between systemic interleukin activity and localized skin inflammation. Although salivary cytokine levels did not differ significantly among groups, strong intra-sample correlations highlight their interaction and support saliva's potential as a non-invasive tool for monitoring immune activity.