Mechanisms And Roles Of Dendritic Cell In Immune Response To Mycobacterium Tuberculosis

ObjectiveTo detect quantitive and functional difference of dendritic cells in patients with mycobacterium tuberculosis, and to investigate the effects of dendritic cells on pathogenesis of patients with tuberculosis, providing the experimental evidence for dendritic cells-based vacancies and immunotherapy protocols of anti-tuberculosis.Methods1. Patients'venous blood was extracted and dendritic cells were detected by using flow cytometry.2. Peripheral blood mononuclear cells were separated and were cultured for 11 days by adding rhGM-CSF, rhIL-4 and rhTNF-α.3. Cellular morphological features and ultra structure characteristics of dendritic cell were observed respectively by using inverted microscope, scanning electron microscope and transmission electron microscope.4. Expression of IL-12p40, IL-12p35 and CCR7 mRNA were analyzed by real time PCR.5. Concentration of IL-12p70 in supernatant was detected by ELISA.Results1. Total DC and DC1 subset in experimental group were (0.42±0.19) %, (0.28±0.13) % respectively, which were significantly lower than they were in control group (P<0.01), no significance of DC2 subset was found between experimental group and control group; total DC and DC1 subset in smear-positive patients were (0.24±0.06) %, (0.16±0.04) % respectively, which were significantly lower than they were in smear-negative patients (P<0.05), no significance of DC2 subset was found between smear-positive and smear-negative groups; there was no significance of total DC, DC1 and DC2 subsets in pretreatment cases and retreatment cases (P>0.05).2. Typical dendritic morphological features were observed by inverted microscope, scanning electron microscope and transmission electron microscope after cultured for 11days by adding rhGM-CSF, rhIL-4 and rhTNF-α.3. RT-PCR showed the expressions of IL-12p40, IL-12p35 and CCR7 mRNA were lower than they were in control group (P <0.05).4. ELISA test showed that concentration of IL-12p70 in experimental group was lower than it was in control group and a delayed secretion peak was also observed.Conclusions1. The mature DC with typical morphological features and function were observed after isolated from human peripheral blood and cultured for 11 days by adding rhGM-CSF, rhIL-4 and rhTNF-α.2. Expressions of IL-12p40,IL-12p35,CCR7 mRNA and IL-12p70 in patients with tuberculosis were lower than they were in healthy controls, indicating an inhibition of DC maturation, which resulted in a decreased immune response.3. The study showed a decreased total DC and DC1 subsets in tuberculosis patients, which might reduce initiation ability for type 1 T cell-mediated immunity, leading to a lower ability to prime immune response to mycobacterium tuberculosis.