Most African-American patients with rheumatoid arthritis do not have the rheumatoid antigenic determinant

• Objective: To evaluate the relation between the pres-ence of the "rheumatoid epitope, " defined by a se-quence motif in the HLA-DRB1 alleles, and disease severity in African-American patients with rheumatoid arthritis. • Design: Cross-sectional study. • Setting: Rheumatology outpatient clinics at two uni-versity medical centers. • Patients: 86 African-American patients with rheuma-toid arthritis (66 seropositive and 20 seronegative for the rheumatoid factor) attending the clinics and 88 healthy African-American persons. • Measurements: HLA-DRB1 alleles were determined by restriction fragment length polymorphism and by allele-specific oligonucleotide typing of polymeras