Evaluation of topoisomerase-1-specific CD8+ T-cell response in systemic sclerosis.
Measurement of disease activity in systemic autoimmune disorders is often unreliable, and immunosuppressive therapy is often titrated to crude clinical response and/or onset of complications. Systemic sclerosis (SSc) presents a distinct clinical phenotype associated with specific autoantibodies. Anti-topoisomerase-1 (SCL-70) is selectively detected in 30-60% of subjects with diffuse skin and interstitial lung involvement. Such patients offer an ideal clinical model to characterize and quantify the autoantigen-specific T-cell response and its correlation with disease phenotype and activity. Human leukocyte antigen A2 (HLA-A2)-restricted topo-1 peptides were selected based on an epitope prediction algorithm. For initial studies, the best binder topo-1(262-270) KMLDHEYTT (#262) was used alone or loaded onto an artificial antigen-presenting platform generated by coupling a dimeric major histocompatibility complex-immunoglobulin G fusion protein (HLA-A2-Ig) and anti-CD28 antibodies onto magnetic beads (artificial antigen-presenting cells). Blood samples (100 microL) from HLA-A2+ SSc patients and cytomegalovirus (CMV) seropositive healthy control subjects were tested in an intracellular cytokine staining assay. Gamma interferon production by CD8+ T cells was measured after stimulation with peptide #262, CMVpp65, or MART-1 (irrelevant peptide). In two of five SCL-70+ patients, peptide #262-loaded aAPCs induced a specific CD8+ T-cell response (0.45% +/- 0.23% of total CD8+ cells). This response was not observed in the seven SCL-70- (five SSc and two CMV+) control subjects studied (0.03% +/- 0.02%). Interestingly, bronchoalveolar lavage fluid obtained from one topo-1-responsive SSc patient who had worsening respiratory function and active alveolitis showed striking enrichment of topo-1-specific CD8+ T cells (3.94%). This small-volume ex vivo assay may prove to be a sensitive and specific tool to assess disease activity and to monitor response to therapy in patients with scleroderma.
Boin
Francesco
F
Division of Rheumatology, The Johns Hopkins University School of Medicine, 5200 Eastern Ave., Mason F. Lord Bldg., Center Tower, Ste. 4100, Baltimore, MD 21224, USA. fboin1@jhmi.edu
Wigley
Fredrick M
FM
Schneck
Jonathan P
JP
Oelke
Mathias
M
Rosen
Antony
A
D001327:Autoimmune Diseases / Q000201:enzymology / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000201:enzymology* / Q000276:immunology*; D016022:Case-Control Studies; D004264:DNA Topoisomerases, Type I / Q000097:blood / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D006801:Humans; D018655:Lymphocyte Count; D010750:Phosphoproteins / Q000276:immunology; D012595:Scleroderma, Systemic / Q000201:enzymology* / Q000276:immunology*; D014763:Viral Matrix Proteins / Q000276:immunology
D018984:Epitopes, T-Lymphocyte; D010750:Phosphoproteins; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D004264:DNA Topoisomerases, Type I