The Study Of NKT Cell And Their Functions In TB Patients And Impact Of α-GalCer On NKT Cells In Mtb-infected Mice

Mtb is the one of lethal pathogens which lead to the mortality for human beings, about 8 millions people suffered from active TB every year all over the world, among which 2 million people died from it.1/3 of population had been infected with MTB and 5-10% of them developed to active TB. The ratio among HIV infected individuals will be higher and now, TB is one of the major health problems in developing countries.BCG was proved effective which can prevent the infection from developing to severe cases including tuberculous meningitis and miliary tuberculosis in childhood. Furthermore, BCG vaccination is a highly cost-effective and it hase been retained in high-incidence countries. Some studies showed that the protective effect of BCG against TB was questioned. Thus it is urgent to investigate the mechanism of host immune response to MTB in order to develop a novel vaccine.NKT cells are a separate lineage of T lymphocyte that can modulate immune responses., their quantity and quality have close relationship with autoimmune and infectious diseases. As powerful innate immune effectors and modulators of adaptive immune responses, NKT cells have many functions that could potentially contribute significantly to immune responses against MTB. Particularly, NKT cells contain preformed IFN-ymRNA in their cytoplasm, and rapidly secrete this cytokine upon T cell receptor stimulation at levels that are up to 200 fold higher than conventional CD4+ T cells. In addition, stimulation of NKT cells in vivo induces maturation of dendritic cells and facilitates their cross-presentation of soluble antigens, leading to increased priming of CD8+ T cell responses.Lipid antigen extracted from MTB can be recognized by NKT cells, and can elicit protective immunity against MTB infection in mice. Not only NKT cells have effectiveness on host immunity against MTB, but also show their killing capability to HIV. How to activate NKT cells and intensify their functions will be an important strategy to the treatment for TB or HIV/TB patients.The aim of the investigation is to find out the effect of a-GalCer on the function and cell accounts of NKT cells in TB patients. Based on the above idea we proposed, the study can be divided into two parts.Part I The quantity and quality of NKT cells in TB patients We have shown that the percentages of circulating NKT cells are selectively and significantly lower in peripheral blood mononuclear cells from individuals with active pulmonary tuberculosis than those in uninfected individuals. NKT cell levels are selectively lower with pulmonary tuberculosis than in healthy control subjects. This apparent loss of NKT cells from the peripheral blood is sustained during the 6 months after the initiation of MTB treatment. These findings indicated that NKT cells may be an important component of anti-tuberculosis immunity. There are several explanations for this obvious loss of NKT cells from the circulation of patients with pulmonary tuberculosis. The circulating NKT cells may have undergone apoptosis as a result of chronic stimulation by glycolipid MTB antigens. Our results showed that NKT cells after stimulation, the secretion of IFN-y increased in healthy volunteers, while IL-4 secretion does not appear to change significantly, TB patients NKT cells are stimulated, It increased the secretion of IFN-y, IL-4 secretion does not appear to change significantly, IL-4 secretion does not appear significant change, NKT cells healthy volunteers TB patients was significantly higher than the number of NKT cells in the NKT. In terms of cell function, TB patients was significantly lower than in healthy volunteers, a significant difference between the two, by drugs in stimulation, IFN-γ -positive patients, tetramerf NKT cells was significantly higher than the healthy control group, IL-4+, tetramer+ NKT cells was significantly lower than the healthy control group, T-SPOT has an important guiding role for the clinical diagnosis ofTB.Part II The impact of a-GalCer on the function of NKT cells in Mtb-infected Balb/c mice. We found in various doses, in the case of different routes of administration, a-GalCer activated NKT cells in the ability of a significant difference. The tail vein administration route, the appropriate dose of 1000ng/10ul;the intranasal route of administration, the dose we found no significant difference. In the case of determining the dose (1000ng/100ul intravenous administration,1000ng/10ul intranasally) intravenous route of administration, the serum, bronchoalveolar lavage fluid, lung homogenate IFN-y secretion in a significant difference in serum is the highest; using the intranasal route of administration, the serum, bronchoalveolar lavage fluid, lung homogenate IFN-y secretion were significantly different, lung homogenate was the highest.Through this study, we found that no matter what the mode of administration, a-GalCer single drug effect is not obvious; Our first application of a-GalCer+RFP administration which showed that the drug combination to treat mice infected with Mtb and RFP alone to drug group had significant difference, intravenous administration is more obvious; These results suggested that after treatment of TB, the inflammatory factors (Thl cytokines and Th2 cytokines) decreased; we found a-GalCer+RFP administered intranasally to mice significantly reduced local inflammatory response in lung tissue.