Comparison of in vitro-specific blood tests with tuberculin skin test for diagnosis of latent tuberculosis before anti-TNF therapy.
BACKGROUND
Latent tuberculosis infection (LTBI) is detected with the tuberculin skin test (TST) before anti-TNF therapy. We aimed to investigate in vitro blood assays with TB-specific antigens (CFP-10, ESAT-6), in immune-mediated inflammatory diseases (IMID) for LTBI screening.


METHODS
Sixty-eight IMID patients with (n = 35) or without (n = 33) LTBI according to clinico-radiographic findings or TST results (10 mm cutoff value) underwent cell proliferation assessed by thymidine incorporation and PKH-26 dilution assays, and IFNgamma-release enzyme-linked immunosorbent spot (ELISPOT) assays with TB-specific antigens.


RESULTS
In vitro blood assays gave higher positive results in patients with LTBI than without (p<0.05), with some variations between tests. Among the 13 patients with LTBI diagnosed independently of TST results, 5 had a negative TST (38.5%) and only 2 a negative blood assays result (15.4%). The 5 LTBI patients with negative TST results all had positive blood assays results. Ten patients without LTBI but with intermediate TST results (6-10 mm) had no different result than patients with TST result </=5 mm (p>0.3) and lower results than those with LTBI (p<0.05) on CFP-10+ESAT-6 ELISPOT and CFP-10 proliferation assays.


CONCLUSIONS
Anti-TB blood assays are beneficial for LTBI diagnosis in IMID. Compared with TST, they show a better sensitivity, as seen by positive results in 5 patients with certain LTBI and negative TST, and better specificity, as seen by negative results in most patients with intermediate TST as the only criteria of LTBI. In the absence of clinico-radiographic findings for LTBI, blood assays could replace TST for antibiotherapy decision before anti-TNF.
Sellam
Jérémie
J
Service de Rhumatologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin Bicêtre, France.
Hamdi
Haifa
H
Roy
Carine
C
Baron
Gabriel
G
Lemann
Marc
M
Puéchal
Xavier
X
Breban
Maxime
M
Berenbaum
Francis
F
Humbert
Marc
M
Weldingh
Karin
K
Salmon
Dominique
D
Ravaud
Philippe
P
Emilie
Dominique
D
Mariette
Xavier
X
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000378:metabolism; D000995:Antitubercular Agents / Q000627:therapeutic use; D001500:BCG Vaccine / Q000008:administration & dosage; D001426:Bacterial Proteins / Q000378:metabolism; D002478:Cells, Cultured; D016009:Chi-Square Distribution; D003424:Crohn Disease / Q000188:drug therapy / Q000382:microbiology; D006801:Humans; D007159:Immunologic Tests; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D007371:Interferon-gamma / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D018579:Patient Selection; D012372:ROC Curve; D011994:Recombinant Proteins / Q000378:metabolism; D012216:Rheumatic Diseases / Q000188:drug therapy* / Q000382:microbiology; D012680:Sensitivity and Specificity; D013936:Thymidine / Q000378:metabolism; D014374:Tuberculin Test; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
D000942:Antigens, Bacterial; D000995:Antitubercular Agents; D001500:BCG Vaccine; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D007166:Immunosuppressive Agents; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D013936:Thymidine