IgA Immune Response against the Mycobacterial Antigen A60 in Patients with Active Pulmonary Tuberculosis

Abstract

Searching for IgG and IgM against the mycobacterial antigen A60 has been recognized as a potential diagnostic tool for pulmonary tuberculosis. The role of detection of anti-A60 IgA in improving diagnostic accuracy of serology is not well known. In this study we measured with ELISA serum levels of both anti-A60 IgG and IgA in 216 subjects. 88 healthy volunteers (44 PPD- and 44 PPD+), 44 patients suffering from nontuberculous lung disease and 15 subjects with healed pulmonary tuberculosis constituted the control population; 69 patients with active pulmonary tuberculosis (35 cavitary forms, 26 productive forms and 8 miliary forms) were examined. The sensitivity of IgG test was 73.9% in pulmonary tuberculosis (77.1% in cavitary forms, 65.4% in productive forms, 87.5% in milary forms); the specificity of the test was 95.9%. For the IgA test we observed a sensitivity of 72.5% (74.3 in cavitary forms, 69.2% in productive forms, 75.0 in miliary forms) and a specificity of 93.9%. Combination of the two tests increased the sensitivity to 84.0% (+10.1 % compared to IgG test, +11.5% compared to IgA test); the specificity decreased to 92.5% (-3.4% vs. IgG test; -1.4 vs. IgA test). In conclusion, the combined use of evaluation of anti-A60 IgG and IgA increases the accuracy of serological diagnosis of pulmonary tuberculosis.

Study of the antibody response against Mycobacterium tuberculosis antigens in Warao Amerindian children in Venezuela

“…Bearing in mind that the sensitivities of culture and smear drop precipitously when applied to children, and other diagnostic test/criteria take on greater importance such as serological tests, especially combined tests (Alifano et al 1996, Gupta et al 1997, Swaminathan et al 1999, Pottumarthy et al 2000, Imaz et al 2001), the present ), anti-PPD IgG ( ), anti-PPD IgE ( ), anti-38 kDa sIgA ( ). The evaluation of positive sera was based on a positive score represented by optical density (OD) values above the cut-off point of the mean value plus 2 standard deviations of sera from a healthy control group (n = 38) from Caracas, the capital of Venezuela.…”

Detection of IgG and IgA against the mycobacterial antigen A60 in patients with extrapulmonary tuberculosis

“…They are characterised by simplicity and rapidity of technical execution as well as financial viability. Searching for IgG9 10 and IgA11 against the antigen 60 (A60), the main thermostable component of Old Tuberculin and Purified Protein Derivative (PPD), provided satisfactory results in terms of sensitivity and specificity in the diagnosis of pulmonary tuberculosis.…”

Be alert to tuberculosis-mediated glomerulonephritis: a retrospective study

“…IgA antibodies, specifically against A-60 mycobacterial antigen, have been demonstrated in the sera of patients with active TB, as have immune complexes of IgA antibodies and mycobacterial antigens [16]. This provides a setting for the pathogenesis of IgAN.…”

“…Although the immune response to M. tuberculosis infection is primarily cell-mediated, recent data suggest the existence of a humoral component [15,16]. Type III allergic reactions induced by immune complexes can cause tissue injury and may be involved in the pathogenesis of TB.…”