ASSOCIATION OF PYRAZOLONE DRUG HYPERSENSITIVITY WITH HLA-DQ AND DR ANTIGENS

Background In sensitive patients pyrazolone drugs can precipitate adve rse reactions ranging from urticaria and angioedema to anaphylactic sh ock, presumably by immunological, IgE-mediated mechanism. However, up to now no genetic factors influencing the development of allergic reac tion have been reported in this type of hypersensitivity. Objective Th e aim of our study was the investigation whether the susceptibility to development of pyrazolone drugs hypersensitivity (PDH) reactions was associated with HLA class II antigens. Methods To test this hypothesis we studied the distribution of HLA-DR and DQ antigens in 26 pyrazolon e sensitive patients and control groups including unselected general p opulation and clearly defined atopic and non-atopic groups. Results Si gnificantly higher frequencies of DQ 7 and DR11 antigens were found in PDH group as compared with control unselected population (RR= 16.48, P < 0.0001; P-cor < 0.002 and RR = 4.57, P = 0.0002; P-cor = 0.003 for DQ and DR antigen respectively). Similarly, statistically significant increased frequencies of DQ 7 and DR11 in patients with PDH were obse rved compared with atopic control group OCR = 18.43, P<0.0001; P-cor < 0.002 and RR = 6.33, P = 0.0007; P-cor = 0.01, for DQ and DR antigen r espectively). However, in comparison to non-atopic control group only the frequency of DQ 7 antigen was significantly increased (RR = 15.42, P = 0.0001; P-cor = 0.0015). DQ 7 antigen was present in 46.1% of PDH patients compared with 4.9%, 4.4% and 5.3% in the general population, atopic and non-atopic groups respectively, suggesting pyrazolone hype rsensitivity as a trait positively correlated with this HLA antigen. C onclusion Our data suggest a genetic predisposition to pyrazolone hype rsensitivity reactions, linked to HLA-DQ locus.