Association of HLA-DRB 1*07 and DRB 1*04 to citrus red mite (Panonychus citri) and house dust mite sensitive asthma

Background Specific IgE responses to allergens provide useful models for ev aluating the genetic factors that control human immune responses. A recent survey demonstrated that the citrus red mite (Panonychus citri, CRM) is the most important allel gen in the development of asthma in citrus farmers. Objective The aim of this study was to evaluate whether susceptibility or r esistance to CRM-induced asthma was associated with HLA-DRB1 gene. Methods DNAs were extracted from two groups of unrelated Korean adults livi ng around citrus farms: (1) Ninety-one adults with CRM-sensitive asthma; an d (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 as thmatics compared to the controls (17.6% vs 4.1%, Pc = 0.01). Conversely, t he 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 betw een 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 d eveloping. the asthma in CRM-exposed adults.