Poststreptococcal reactive arthritis (PSRA) is characterized by the occurrence of a protracted arthritis that is poorly responsive to salicylate or other NSAID therapy. Patients with PSRA have evidence for antecedent group A streptococcal infection but lack the required criteria for the diagnosis of acute rheumatic fever. Based on current data, about 6% of patients with PSRA who do not receive antibiotic prophylaxis will acquire cardiac valvular disease.

Previous studies have shown that reactive arthritis is associated with HLA-B27, while rheumatic fever is associated with certain DRB1 alleles. In order to assess the relationship of PSRA to other forms of reactive arthritis and to rheumatic fever, we determined the frequency of HLA-B27 and HLA-DRB1 in 25 patients identified in our rheumatology clinic as having PSRA. The results of the DRB1 genotyping, performed using the sequence-specific-priming technique on 18 Caucaian-American patients were compared with the results obtained on 33 patients with rheumatic fever and on 190 normal controls of the same racial extraction.

HLA-B27 was positive in only 3 of 20 PSRA patients on whom the test was performed. Patients with PSRA had a significantly higher frequency of DRB1*01 than controls (8/18 vs 43/190; p=0.046) or rheumatic fever patients (8/18 vs 6/33; p=0.050), while rheumatic fever patients had a significantly higher frequency of DRB1*16 than controls (5/33 vs 8/190; p=0.016).

These results indicate that unlike other forms of reactive arthritis, PSRA is not associated with HLA-B27. In addition, PSRA shows an association with a different DRB1 allele than rheumatic fever. This latter finding, while suggesting a genetic association in PSRA, seems to support the concept that PSRA is a distinct clinical entitiy that has a different pathogenetic mechanism than rheumatic fever.