Human pulmonary tuberculosis (TB) is a worldwide public health problem, which is caused by Mycobacterium tuberc-ulosis. It is a fact that one third of the world ' s population is infected with this mycobacteria, however , only a minority of people infected by M. tuberc-ulosis may develop a clinical dis- ease. In general, about 90% have their bacilli under control in a latent state throughout their lives by means of their immune responses. About 5% will de- velop primary progressive TB and th<} remaining 5% will develop the disease in the later stages of their lives, which is known as reactivation or post-primary TB. In resistant individua1s, control of the infection mainly requires develop- ment of a Thl cell immunity response. This type of response involves participa- tion of a1veolar macrophages and T CD4 + , CD8 + and T yt5 Iymphocytes, and production of cytokines such as IL-2, IFN-y, IL-12, IL-18 and TNF-a, as well as chemokines such as MNTES, MCP-l, MIP-la and IL-8 which playan important role in the migration of different cell subpopulations to the infection site for the formation of granulome. In addition, the role of "natural killer" (NK) cells, a1ong with epitelial cells, is essentia1 as part of the innate immune response.