Association of HLA-DRB1*07 and DRB1*04 to citrus red mite (Panonychus citri) and house dust mite sensitive asthma

Abstract

Background Specific IgE responses to allergens provide useful models for evaluating the genetic factors that control human immune responses. A recent survey demonstrated that the citrus red mite (Panonychus citri, CRM) is the most important allergen in the development of asthma in citrus farmers. Objective The aim of this study was to evaluate whether susceptibility or resistance to CRM-induced asthma was associated with HLA-DRB1 gene. Methods DNAs were extracted from two groups of unrelated Korean adults living around citrus farms: (1) Ninety-one adults with CRM-sensitive asthma; and (2) 98 exposed, healthy nonatopic controls. Genotypes of HLA-DRB1 alleles were carried out using PCR-based methods. Results Allelic frequency of HLA-DRB1*07 was higher in the CRM-sensitive asthmatics compared to the controls (17.6% vs 4.1%, Pc=0.01). Conversely, the frequency of DRB1*04 was lower in the CRM-sensitive asthmatics compared to the controls (19.8% vs 40.8%, Pc = 0.01). No significant difference was found in the distributions of the other HLA-DRB1 gene-encoded antigens between the two groups. Conclusion HLA-DRB1 genes may be involved in the development of CRM-induced asthma. In addition, HLA-DR7 may increase, and DR4 decrease, the risk of developing the asthma in CRM-exposed adults.