ANTI-KP 90 IGA ANTIBODIES IN THE DIAGNOSIS OF ACTIVE TUBERCULOSIS

Background: Accurate diagnosis of active tuberculosis (TB) has been di fficult historically, yet a great demand persists for a rapid and reli able diagnostic method. Detection of Mycobacterium tuberculosis anti-K p 90 IgA antibodies is one of the more novel techniques. Study objecti ves: To evaluate the diagnostic value of a recently developed enzyme-l inked immunosorbent assay (ELISA) test, which detects IgA antibodies a gainst M tuberculosis Kp 90 antigen, and to compare the results with c onventional diagnosis and the polymerase chain reaction (PCR) method. Participants: Serum, ethylenediaminetetraacetic acid (EDTA)-blood, and body fluid samples were obtained from 51 patients with active TB and 71 control subjects. The clinical diagnosis of TB was supported by a p ositive culture (n = 6), detection of acid-fast bacilli on smear (n = 35), or both (n = 10). Measurements and results: IgA antibodies were d etected in sera and/or body fluid samples from 82% of patients with TB and 10% of controls. M tuberculosis DNA was detected in body fluid sa mple of 96% and blood sample of 49% of patients with TB by PCR. None o f the blood and 5.6% of the body fluid specimens from controls were PC R-positive. Conclusions: Anti-Kp 90 IgA antibodies were detected using ELISA in 78% of serum and 69% of body fluids from patients with TB, t herefore, this test is promising for the diagnosis of active TB and ap pears to be more reliable, particularly for body fluid samples.