Correlation of the relative binding affinity of the Borrelia burgdorferi outer-surface protein A (OspA)163–175 peptide for 14 HLA-DR molecules and percentage allele frequencies of these HLA-DR molecules in patients with antibiotic-refractory Lyme arthritis (antibiotic-refractory patients) or antibiotic-responsive Lyme arthritis (antibiotic-responsive patients). Seven of the 14 DRB molecules, which showed strong-to-weak binding of OspA163–175, were more common among patients with antibiotic-refractory arthritis, whereas the other 7 DRB molecules, which showed negligible or no binding of the peptide, were more common among patients with antibiotic-responsive arthritis. Reproduced with permission from Steere et al [16].