Role of immunotherapy in the treatment of tuberculosis

Tuberculosis is caused byMycobacterium tuberculosis, an intracellular pathogen residing in macrophages. Cell mediated immune (CMI) and delayed type of hypersensitive (DTH) responses play a pivotal role in providing protection to the host. The most important cell is the CD4 T lymphocyte, which is divided into TH1 and TH2 subsets depending on the type of cytokines produced. TH1 cells produce the cytokines interferon-gamma and interleukin-2, which are important for activation of antimycobacterial activities and essential for the DTH response. Grange opines that the immune response in an individual with tuberculous infection gets 'locked in' to one or other pattern of response viz. TH1 or TH2 response, the latter response leading to tissue damage and progression of disease.Stanford and co-workers conducted several studies on the effectiveness ofMycobacterium vaccae, as an immunotherapeutic agent for tuberculosis. It is non-pathogenic in humans and is thought to be a powerful TH1 adjuvant. A series of small studies pointed thatM. vaccae has a beneficial effect and there is enough evidence now to show that its use as an immunotherapeutic agent, as an adjunct to chemotherapy in the treatment of tuberculosis especially at a time when drug resistance is rampant, appears promising.