Production & characterization of monoclonal antibodies to Mycobacterium tuberculosis

Monoclonal antibodies (MAbs) against Mycobacterium tuberculosis H37Rv culture filtrate (CF) were raised by immunizing BALB/c mice and characterization was done. Attempts have been directed towards identifying mycobacterial antigens in biological fluids by employing polyclonal and monoclonal antibodies specific for M. tuberculosis. Immunohistologic studies, using MAbs for the localization of whole or fragmented bacilli in the biopsy specimens were also carried out.

Intrasplenic IS and intraperitoneal i.p. routes of immunization, were compared. The MAbs were characterized for their isotype, binding specificity, nature of binding epitope, reactivity in immunoassays etc.

IS and i.p. routes of immunization, were compared and i.p. was found superior. Ten MAbs designated TRC 1-10 were produced. Of these, 7 MAbs, TRC 1-7 reacted with the 30/31 kDa doublet (antigen 85 complex), TRC 8 with 12 kDa in addition to 30/31 kDa and TRC 9 and 10 with the 24 and 12 kDa antigens respectively. Six MAbs were classified as broadly cross reactive and 2 showed limited cross reactivity. TRC 8 and 10 showed species specificity. Employing TRC 8 in sandwich ELISA, antigen was detected in sera from 17 of 25 pulmonary tuberculosis patients and 3 of 20 controls. TRC 8 was found to be useful in detecting antigens specifically in M. tuberculosis and M. leprae infected tissues, by immunoperoxidase staining.

TRC 8 was found to be restricted in its reactivity to M. tuberculosis complex and M. leprae. TRC 8 may prove useful in immuno-diagnosis of tuberculosis.