title: Elevated serum level of soluble HLA class I antigens in patients with systemic lupus erythematosus.
abstract: OBJECTIVE
  To examine the clinical significance of serum soluble HLA class I antigens (sHLA class I) in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).
  
  
  METHODS
  Serum levels of sHLA class I were measured by enzyme-linked immunosorbent assay, using a monoclonal antibody against monomorphic determinant of HLA class I (W6/32) and an enzyme-labeled polyclonal antibody to human beta 2-microglobulin.
  
  
  RESULTS
  The serum sHLA class I concentration was 1.85 +/- 1.15 micrograms/ml (mean +/- SD) in 27 patients with SLE (P < 0.0001 versus normal controls, P = 0.0001 versus RA), 0.61 +/- 0.34 micrograms/ml in 16 patients with RA (P = 0.02 versus normal controls), and 0.41 +/= 0.20 micrograms/ml in normal controls. The HLA class I levels were significantly correlated with the SLE Disease Activity Index (r = 0.62, P = 0.0004) and with a reduction of CH50 levels (r = -0.60, P = 0.0007). A longitudinal analysis of patients with SLE indicated that serum sHLA class I levels fluctuated in conjunction with other disease activity markers.
  
  
  CONCLUSIONS
  Serum sHLA class I may be useful as a disease activity marker of SLE. The mechanism of secretion and the physiologic role of sHLA class I require further study.
authors.affiliation: Department of Medicine and Physical Therapy, University of Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Tsuchiya
authors.forename: M
authors.initials: M
authors.lastname: Shiota
authors.forename: A
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: K
authors.initials: K
authors.lastname: Ito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000276:immunology; D002493:Central Nervous System Diseases / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000097:blood*; D006801:Humans; D008137:Longitudinal Studies; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008875:Middle Aged; D012016:Reference Values; D012995:Solubility; D001613:beta 2-Microglobulin / Q000032:analysis
chemical_list: D015395:Histocompatibility Antigens Class I; D001613:beta 2-Microglobulin