HLA-Cw*0602 associates with a twofold higher prevalence of positive streptococcal throat swab at the onset of psoriasis: a case control study

BMC Dermatol. 2009 May 29;9:5. doi: 10.1186/1471-5945-9-5.


Background: The influence of streptococcal infections in the pathogenesis of psoriasis is not yet understood. In vitro data suggest that streptococcal factors influence T-cell function in psoriasis in a HLA-dependent manner, but studies designed to measure the HLA-C/Streptococci interaction are lacking. In the present study, we hypothesized that there is a statistical interaction between the result of streptococcal throat cultures and the presence of the HLA-Cw*0602 allele in psoriasis patients.

Methods: We performed a case control study using the "Stockholm Psoriasis Cohort" consisting of patients consecutively recruited within 12 months of disease onset (Plaque psoriasis = 439, Guttate psoriasis = 143), matched to healthy controls (n = 454) randomly chosen from the Swedish Population Registry. All individuals underwent physical examination including throat swabs and DNA isolation for HLA-Cw*0602 genotyping. The prevalence of positive streptococcal throat swabs and HLA-Cw*0602 was compared between patients and controls and expressed as odds ratios with 95% confidence intervals. Associations were evaluated separately for guttate and plaque psoriasis by Fisher's exact test.

Results: Regardless of disease phenotype, the prevalence of positive streptococcal throat swabs in HLA-Cw*0602 positive patients was twice the prevalence among HLA-Cw*0602 negative patients (OR = 5.8 C.I. = 3.57-9.67, p < 0.001), while no difference was observed among Cw*0602 positive versus negative controls. The corresponding odds ratios for the guttate and plaque psoriasis phenotypes were 3.5 (CI = 1.5-8.7, p = 0.01) and 2.3 (CI = 1.0-5.1, p = 0.02) respectively.

Conclusion: These findings suggest that among HLA-Cw*0602 positive psoriasis patients, streptococci may contribute to the onset or exacerbation of the inflammatory process independent of the disease phenotype. However, studies on the functional interaction between HLA-C and streptococcal factors are needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Female
  • Genetic Predisposition to Disease / epidemiology
  • Genotype
  • HLA-C Antigens / genetics*
  • Humans
  • Male
  • Middle Aged
  • Pharyngitis / epidemiology
  • Pharyngitis / genetics
  • Pharyngitis / microbiology
  • Prevalence
  • Psoriasis / epidemiology*
  • Psoriasis / genetics*
  • Registries
  • Streptococcal Infections / epidemiology*
  • Streptococcal Infections / genetics*
  • Young Adult


  • HLA-C Antigens
  • HLA-C*06:02 antigen