The CD14 C-159T polymorphism is not associated with asthma or asthma severity in an Australian adult population

Background: CD14 functions as a multifunctional receptor for bacterial cell wall components including endotoxin and lipopolysaccharide and is likely to play a role in the polarisation of T lymphocytes into Th1 and Th2 subsets, thereby influencing the cytokine profile and subsequent IgE production in response to antigen/ allergen contact in allergic phenotypes. A functional C-159T polymorphism has been described in the promoter region of the gene and has been associated with increased gene expression, atopy, and nonatopic asthma in different ethnic populations. A study was undertaken to examine the association between the C- 159T polymorphism and asthma, asthma severity, and atopy in a large Australian white population. Methods: PCR- RFLP analysis was used to characterise the C- 159T polymorphism in mild ( n = 264), moderate ( n = 225) and severe ( n = 79) asthmatic patients and non- asthmatic controls ( n = 443), including atopic ( n = 688) and non- atopic ( n = 323) individuals. Association analyses were performed using x 2 tests. Results: There was no association between the polymorphism and asthma ( p = 0.468) or asthma severity ( p = 0.727), and only a very weak association with atopy ( p = 0.084). A meta- analysis of all studies conducted to date revealed similar genotypic frequencies in white ethnic populations and confirmed that there was no overall association with atopy ( p = 0.52) or asthma ( p = 0.23), although there was significant between study heterogeneity ( p = 0.01). Conclusions: This study confirms that there is no association between the CD14 C- 159T polymorphism and asthma or asthma severity and a weak association between this polymorphism and atopy in an adult population.