title: Tuberculin skin test, interferon-gamma assay, and T cells subpopulations in hemodialysis patients.
abstract: OBJECTIVE
  To examine and compare the responses of hemodialysis (HD) patients to Mycobacterium tuberculosis antigens by using the tuberculin skin test (TST) and an interferon gamma assay (IFN-TB), and to investigate the relationship between T cells subpopulations and tests results. Observational, prospective, diagnostic study conducted in a HD center in a country with high prevalence of tuberculosis.
  
  
  METHODS
  195 patients on maintenance HD who consented to participate in this study; 187 (6 were excluded for refusing TST and 2 for indeterminate responses to IFN-TB) were HIV negative, vaccinated with the Bacille Calmette-Guerin vaccine, and without any signs of active tuberculosis, were selected.
  
  
  METHODS
  Similar to the Mantoux method, 10 IU tuberculin was used for the TST. An IFN-gamma assay specific for Mycobacterium tuberculosis antigens and phytohemagglutinin was carried out. Flow cytometry analysis of peripheral lymphocytes was also performed.
  
  
  RESULTS
  TST and IFN-TB results were found to be positive (44% and 53%, respectively) or negative (32% and 47%, respectively) in similar proportions. Results were in agreement in 71% of positive and 58% of negative tests. IFN-gamma levels were found to be higher in patients with a positive TST. All cell counts and CD4/CD8 were found to be higher in TST-positive patients, whereas only total lymphocytes count and CD4/CD8 were reported to be high in IFN-TB-positive patients. A model of multivariable linear regression including cell counts explained 16% of the mitogen-induced IFN-gamma production (F = 5,11; P = .0003). The majority of subjects with positive tests were younger, in most cases male, belonged to the Roma ethnic group, had a shorter HD vintage, and a better nutritional status.
  
  
  CONCLUSIONS
  TST and IFN-gamma production stimulated by Mycobacterium tuberculosis antigens rely on patient's immune status, which could be influenced by either individual (age, gender), dialysis-related (HD vintage), or nutritional factors. In addition, the diagnostic utility for tuberculosis is similar and moderate in HD patients.
authors.affiliation: Nephrology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. ligiarares@yahoo.com
authors.forename: Ligia
authors.initials: L
authors.lastname: Petrescu
authors.forename: Simona
authors.initials: S
authors.lastname: Stancu
authors.forename: Gratiela
authors.initials: G
authors.lastname: Tardei
authors.forename: Caterina
authors.initials: C
authors.lastname: Santimbrean
authors.forename: Mircea
authors.initials: M
authors.lastname: Penescu
authors.forename: Gabriel
authors.initials: G
authors.lastname: Mircescu
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology; D016516:CD4-CD8 Ratio; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis / Q000096:biosynthesis*; D007674:Kidney Diseases / Q000150:complications / Q000276:immunology / Q000628:therapy; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D010835:Phytohemagglutinins; D011446:Prospective Studies; D006435:Renal Dialysis; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014374:Tuberculin Test; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D010835:Phytohemagglutinins; C072681:Mycobacterium tuberculosis antigens; D007371:Interferon-gamma