Background It should be noted considerable incidence rate of reactive arthritis (ReA) in the last decades and the fact that the majority of them are due to Chlamydia trachomatis infection (CTI) [1,2]. In some patients with CTI ReA and chronic ReA will develop [3,4], therefore search for risk factors of possible ReA development in CTI patients is an essential problem.
Objectives To perform the typing of ReA patients induced by CTI for HLA antigens in order to reveal possible genetic markers of susceptibility and resistance to ReA development.
Methods 30 ReA patients observed in Byelorussian Republican Rheumatologic Center (17 women and 13 men from 19 to 56 years old, mean age 36.4±10.5 years) with urogenital CTI confirmed by culture and immunofluorescence serology were studied for frequency of I and II class HLA antigens (A, B, C, DR, DQ locus, total number of studied specificities - 71) by means of microdroplet lymphocyte cytotoxicity test. Data on frequency of I and II class HLA antigens in 308 and 106 unrelated Minsk (Belarus) inhabitants were used as a control.
Results We revealed significant increase of antigen frequency in B locus for B27 (χ2=26.5; pcorr=0.00025; RR=5.7) and B60 (χ2=4.3; p<0.05; RR=2.7) antigens, in DR locus for DR1 (43.3% in ReA vs 16.6% in controls, χ2=10.1; RR=4.0) and DR13 (40.0% in ReA vs 21.7% in controls, χ2=4.1; RR=2.4) antigens as well as for phenotype DR1,DR13 frequency (χ2=5.3; p<0.05, RR=5.3) in ReA patients. In addition significant decrease of DR7 (10.0% vs 32.1% in controls, χ2=5.8; RR=-4.2), DR11 (13.3% vs 31.1%, χ2=3.7; RR=-2.9) and DR53 (23.3% vs 47.2% χ2=5.4; RR=-2.9) antigen frequency was revealed in ReA patients. We registered significant increase of antigen DQ5 frequency (56.7% vs 28.3%, χ2=8.3; RR=3.3) as well as phenotype DQ5,6 frequency (χ2=10.1; RR=16.2) and significant decrease of antigen DQ2 frequency (20.0% vs 37.7%, χ2=3.4; RR=-2.4) in ReA patients in comparison with controls.
Conclusions The revealed genetic markers of susceptibility to ReA development in patients with urogenital CTI are: HLA B27, B60, DR1, DR13, DQ5 antigens, as well as DR1, DR13 and DQ5, DQ6 phenotypes. We consider DR7, DR11, DR53, DQ2 antigens as factors of resistance to ReA development.
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Disclosure of Interest None declared