Mtb Case Study

1) What is the significance of infection with MTB? The significance of infection with MTB is that MTB attacks antigen-presenting cells, resulting in decreased MHC II antigen presentation. In order to find out whether MHC II is expressed on antigen-presenting cells, mice were infected with GFP(-) cells that were expressing BCG through aerosol infection.

2) From the introduction of the paper, how does MTB evade the immune system? MTB evades the immune system by invading macrophages. These macrophages are what harbor the mycobacteria causing mycobacterial inhibition of MHC II.

3) Infection models ***in your own words or with diagrams*** Mice were used as infection models because they create a similar simulation of a pulmonary mycobacterial infection in
In order to produce macrophages, the bone marrow cells were cultured for 7 to 12 days, followed by antigen-processing assays or flow cytometry. In vivo, soluble ovalbumin peptide, or OVA, was added to the macrophages.

b. Describe how mice were infected. The mice were infected through aerosol infection. Aerosol infection summarizes the natural route of mycobacterial infection. After the mice are aerosol infected with BCG, bacteria starts to flourish within 4 to 5 weeks. Cells from 2 to 10 mice in each experimental group were put together to produce BAL, total lung homogenate, CD11b antigen-assorting cells as well as CD11c antigen-assorting cells. The samples from the mice were obtained and cultured to be able to determine the colony forming units or bacterial load.

4) How is antigen presentation measured in this study? Antigen presentation was measured by preparing homogenates from post-washed lungs of naive mice. CD11c affinity-assorting cells were prepared the same way. A flow cytometer was used to sort the antigen-presenting cells by CD11b/CD11c