HLA‐B27‐derived peptides as autoantigens for T lymphocytes in ankylosing spondylitis

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Abstract
Objective.To study whether peptides derived from the HLA‐B27 molecule sequence can stimulate peripheral blood T lymphocytes (PBL) from patients with HLA‐B27‐associated spondylarthropathies.Methods.PBL from 55 HLA‐B27+ patients with ankylosing spondylitis (AS), 28 HLA‐B27+ patients with other spondylarthropathies, 7 rheumatoid arthritis patients, and 30 HLA‐B27+ and 22 HLA‐B27‐ healthy controls were tested in lymphocyte proliferation assays with 4 synthetic peptides derived from the HLA‐B*2705 molecule.Results. A 13‐mer peptide (B27PA) induced significant proliferative responses in 17 of the 55 AS patients (stimulation index [SI] 2.5–17.5), as well as in 3 of the HLA‐B27+ healthy controls (SI 2.5–9.8). Another 13‐mer peptide (B27PC) induced PBL proliferation (SI 2.7–5.5) in 10 AS patients and in some donors of the control groups. In B27PA‐specific T cell lines, an expansion of cells positive for the γ/δ T cell receptor could be demonstrated.Conclusion. These results indicate that HLA‐B27‐derived peptides can be recognized as autoantigens by PBL of HLA‐B27+ AS patients and B27+ healthy controls. Recent infections preceding the manifestation of AS may be involved in this process of anti‐self major histocompatibility complex reactivity.