title: CD69 expression on lymphocytes and interleukin-15 levels in synovial fluids from different inflammatory arthropathies.
abstract: OBJECTIVE
  The aim was to study a possible relationship between CD69 expression on lymphocytes and interleukin-15 (IL-15) levels in synovial fluid (SF) from patients with different inflammatory arthropathies.
  
  
  METHODS
  CD69 expression was assessed by two-color flow cytometry on different subsets of synovial fluid lymphocytes (SFL) obtained from patients with diagnoses of rheumatoid arthritis (RA), seronegative spondyloarthropathy (SSd), and crystal-associated arthritis (CAA). The IL-15 levels in synovial fluid supernatants were measured by enzyme-linked immunoassay (ELISA).
  
  
  RESULTS
  No significant differences between the three groups of arthropathies were observed in the distribution of synovial fluid lymphocyte subsets. CD69-positive SFL were mainly CD3-, CD45RO-, and CCR5-positive cells. Although no significant differences in the percentage of CD69-positive lymphocytes were observed between the three groups of patients, the highest level of CD69 expression on lymphocytes was observed in RA patients (mean fluorescence intensity 37.9 +/- 5.2 compared to 17.5 +/- 3.3 in SSd and 12.4 +/- 2.6 in CAA, P = 0.007 and P < 0.001, respectively). In addition, the expression of CD69 on SFL from RA correlated with their respective IL-15 levels measured in SF supernatants.
  
  
  CONCLUSIONS
  Our data provide in vivo evidence of the putative role that IL-15 can play in the high expression of CD69 on SFL from RA patients.
authors.affiliation: Rheumatology Department, Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Ortiz
authors.forename: Armando
authors.initials: A
authors.lastname: Laffon
authors.forename: Isidoro
authors.initials: I
authors.lastname: Gonzalez-Alvaro
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000032:analysis* / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D019409:Interleukin-15 / Q000032:analysis*; D037181:Lectins, C-Type; D008297:Male; D008875:Middle Aged; D011336:Probability; D011379:Prognosis; D012216:Rheumatic Diseases / Q000175:diagnosis* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D025241:Spondylarthritis / Q000175:diagnosis* / Q000503:physiopathology; D018709:Statistics, Nonparametric; D013582:Synovial Fluid / Q000737:chemistry / Q000276:immunology*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D015415:Biomarkers; D019409:Interleukin-15; D037181:Lectins, C-Type; D000099192:CD69 Antigens