Association between human demodicosis and HLA class I.

Demodex folliculorum and D. brevis are obligatory parasites in hair follicles and in pilosebaceous glands of human skin. Although most people are infested with these mites, only a small number develop the clinical symptoms of skin demodicosis. The objective of this study was to determine the association between HLA specificity and demodicosis. Twenty-five patients with human demodicosis and 150 controls were typed for HLA-A, B, Bw, and Cw using the microlymphocytotoxicity method. The immune response was evaluated by identifying membrane markers of different immune cells using monoclonal antibodies. An association between the frequency of HLA Cw2 and Cw4 haplotypes and human demodicosis was established. The risk of developing clinical symptoms of this disease is 5.0 times higher for people with the Cw2 phenotype and 3.1 times higher for those with the Cw4 haplotype. Individuals who have the HLA A2 phenotype are 2.9 times more resistant to demodicosis. A positive correlation between demodicosis and the haplotypes A3-Cw4, A3-Cw2, A3-B17, A3-B35 and B35-Cw4 was found. In addition, an association between Cw2 and Cw4 alleles in the phenotype of patients with demodicosis and a decrease in the number of natural killer cells was found.