Association of IL-4 polymorphism with severe periodontitis in a sample of Iraqi population.

Introduction: Specific bacterial plaque and environmental factors cannot be considered the only cause of periodontitis. Still, several genetic factors affect the host response to the bacteria, like gene polymorphisms in anti-inflammatory cytokines. Several studies have reported that clones of T-helper 2 lymphocytes (TH2) are generated in response to dental plaque in periodontitis patients, while in healthy individuals, they are regulated by T-helper 1 (TH1) lymphocytes. Accordingly, such patients consistently produce more IL-4 (TH2) in response to bacterial stimulation, whereas healthy controls with intact periodontal tissues produce a significantly higher level of TH1.