Introduction: We compared the salivary immunoglobulin A (IgA) and lysozyme concentration and secretion rates among mild and severe psoriasis patients and controls in Singapore.Materials and Methods: Fifty-one psoriasis patients and 24 controls participated in the study. None of the patients were on immunosuppressive therapy. The Psoriasis Area and Severity Index (PASI) was used to assess the severity of psoriasis. Patients were divided into mild and severe groups by the median PASI score. Each subject contributed a 5-minute unstimulated salivary sample. Enzyme-linked immunosorbent assay method was used to determine the salivary IgA and lysozyme levels. Results: Psoriasis patients had lower concentration and secretion rate of IgA (geometric mean [GM], 97.5 μg/mL and 32.3 μg/min) and lysozyme (GM, 127.6 μg/mL and 42.1 μg/min) than controls (IgA GM 256.3 μg/mL, 79.1 μg/min; lysozyme GM 180.9 μg/mL, 55.8 μg/min) [P = 0.000 (IgA concentration), P = 0.000 (IgA secretion rate), P = 0.015 (lysozyme concentration) and P = 0.150 (lysozyme secretion rate)]. However, no significant differences were observed between mild and severe patients for both IgA and lysozyme concentrations and secretion rates. PASI score showed negative, but non-significant, correlations with either log salivary IgA (r = -0.22, P = 0.13) or log lysozyme (r = -0.09, P = 0.53) secretion rates. Conclusion: Psoriasis patients had lower concentrations and secretion rates of salivary IgA and lysozyme compared to controls. However, among patients, the salivary IgA and lysozyme levels are variable and not related to severity of psoriasis.
The pathophysiological mechanisms in psoriasis are still unclear. Many factors, such as infection, trauma and stress, could cause psoriasis.
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