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

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.