Production of monoclonal antibodies to lipoarabinomannan-B and use in the detection of mycobacterial antigens in sputum

ABSTRACT

Tuberculosis has traditionally been confirmed by AFB staining or culturing Mycobacterium tuberculosis from clinical specimens. However, because of the low sensitivity of the sputum smear examination and of the delayed report in culturing, the conventional methods for detection of M. tuberculosis have not been always satisfactory. In an attempt to develop an alternate tool, this study was initiated to produce monoclonal antibodies (MAb) to lipoarabinomannan B (LAM-B) antigen and to use the antibodies in detecting mycobacteria. In this study, five monoclonal antibodies specific to LAM-B were produced; LAM701 (IgG3), LAM138 (IgM), LAM204 (IgM), LAM302 (IgM), and LAM604 (IgM). A sandwich enzyme-linked immunosorbent assay (ELISA) was developed for detecting LAM-B and other mycobacterial antigens using the monoclonal antibodies. With the MAb LAM701, the minimal detectable concentration was 1.0 ng/ml for LAM-B, and 1.0 microgram/ml for M. tuberculosis whole cells, respectively. When 14 clinical specimens proven to contain AFB by smear staining or culture were examined, ten (71.4%) were positive by the sandwich ELISA; in contrast, sputum smear examination gave positive results in only six (42.9%) specimens. Meanwhile, none of 25 specimens with no evidence of AFB were positive by the sandwich ELISA using the MAb LAM701. Although further evaluations are required, this study suggests that the monoclonal antibodies to LAM-B may be useful in detecting mycobacteria from clinical specimens.