[Evaluation of humoral immune response against mycobacterial antigens in bronchoalveolar lavage fluid from patients with pulmonary tuberculosis confirmed by genetic and culture methods].

INTRODUCTION

The resistance to TB is cells-mediated but humoral response is common and may be correlated with the lack of effective local cellular defence mechanisms. The goal of the study was to evaluate IgG, IgA and IgM mediated humoral immune response against 38kDa plus 16kDa and 38kDa plus lipoarabinomannan (LAM) mycobacterial antigens in BALF from patients with culture confirmed and PCR positive pulmonary tuberculosis (TB) compared to non-tuberculous controls (NTB).

MATERIAL AND METHODS

79 BALF samples (46 TB and 30 NTB) were examined. In 25 BALF samples from TB patients nucleic acids from M. tuberculosis were detected by PCR method. Commercially available ELISA - based assays against proteins 38kDa and 16kDa or 38kDa plus LAM were used. Three different dilutions of BALF: 1 : 1 and 1 : 10 were tested. Mean IgG level against 38 + LAM was significantly higher in TB group compared to control (p < 0,0001). No difference was observed between TB and NTB group in titer of IgM antibodies.

RESULTS

Sensitivity of the tests based on IgG anti38kDa + 16kDa was 49%, IgG anti38kDa + LAM - 33%, IgA anti38kDa + LAM - 100%, IgM anti38kDa + LAM - 35%. Specificity of examined assays: IgA anti38kDa + LAM - 13%, IgM anti38kDa + LAM - 75%, IgG anti38kDa + 16kDa - 87%, IgG anti38kDa + LAM - 93%. The findings of the study indicate that TB is associated with the presence of detectable levels of antibodies in the BALF.

CONCLUSIONS

Examined tests detecting IgG in BALF can be used in combination with other diagnostic methods to increase diagnostic accuracy of pulmonary TB.