title: Baseline numbers of circulating CD28-negative T cells may predict clinical response to abatacept in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To evaluate the number of circulating CD28-negative (CD28-) T cells as a predictor of clinical response to abatacept in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Peripheral blood CD28- T cell subsets were evaluated by flow cytometry at baseline in 32 patients with RA treated with abatacept. Receiver-operator curves were applied to examine the predictive value of T cell populations and to choose the cutoff for the best performance of the test. Remission was defined using the Disease Activity Score 28 based on C-reactive protein.
  
  
  RESULTS
  The overall predictive values of the CD8+CD28- and CD4+CD28- cells for remission after 6 months of abatacept therapy were 0.802 (SE 0.078) and 0.743 (SE 0.089), respectively. Cutoff values of < 87 CD8+CD28- cells/μl and < 28 CD4+CD28- cells/μl had 80.0% sensitivity and 81.8% specificity (Fisher test: p = 0.001), and 60.0% sensitivity and 77.3% specificity (p = 0.043), respectively, for prediction of remission at 6 months. Patients having low baseline numbers of CD8+CD28- T cells had a more than 4-fold higher probability of achieving remission within 6 months than patients with higher levels of these cells.
  
  
  CONCLUSIONS
  A simple laboratory measure, the baseline number of circulating CD28- T cells, predicted remission after 6 months of abatacept treatment in patients with RA.
authors.affiliation: Rheumatology and Clinical Immunology Service, Spedali Civili di Brescia, piazzale Spedali Civili 1, 25123 Brescia, Italy.
authors.forename: Mirko
authors.initials: M
authors.lastname: Scarsi
authors.forename: Tamara
authors.initials: T
authors.lastname: Ziglioli
authors.forename: Paolo
authors.initials: P
authors.lastname: Airo'
mesh_terms: D000069594:Abatacept; D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology* / Q000378:metabolism; D018106:CD28 Antigens / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D016896:Treatment Outcome
chemical_list: D018501:Antirheumatic Agents; D018106:CD28 Antigens; D018796:Immunoconjugates; D000069594:Abatacept