1. True/False: Unlike innate immune responses, adaptive immune responses are ini
ID: 204111 • Letter: 1
Question
1. True/False: Unlike innate immune responses, adaptive immune responses are initiated in secondary lymphoid organs. However, the innate immune response to an infection in a tissue has a pivotal role in inducing T-cell responses in the nearest lymph node by activating tissue dendritic cells and inducing their migration to the lymph node.
2. A mouse is infected with staphylococcal bacteria through a laceration in the skin of its paw. Dendritic cells are isolated from the tissue at the site of infection, and are incubated together with naïve staphylococcal-specific CD4 T cells. Seventy-two hours later, the proliferation of the CD4 T cells is measured as a readout for T cell activation. Surprisingly, the T cell response is quite poor compared to the response observed when the same T cells are mixed with a comparable number of dendritic cells isolated from the draining lymph node of the infected mouse. A comparison of the dendritic cells isolated from the two different sites would reveal:
A. Much higher levels of MHC and B7 molecules on the lymph node dendritic cells than those from the infected tissue
B. Much higher expression of all TLRs in the lymph node dendritic cells than those from the infected tissue
C. Increased phagocytic activity of the lymph node dendritic cells than those from the infected tissue
D. Increased expression of Dectin-1, DEC205, and DC-SIGN on the lymph node dendritic cells than on those from the infected tissue
3. Many virus infections induce robust production of type I interferons, IFN-alpha and IFN-beta. One example is the herpes simplex virus-1 (HSV-2), one of the most common sexually transmitted diseases in the US. Experiments that investigated the immune response to HSV-2 using a mouse model demonstrated essential roles for the DNA sensing Toll-like receptor, TLR9, and its downstream signaling adapter, MyD88, in the production of type I interferons following HSV-2 immunization. The type I interferonresponse to HSV-2 would be restored in Tlr9-/-mice by transferring into these mice wild-type:
A. Macrophages
B. Conventional dendritic cells
C. Mast cells
D. Plasmacytoid dendritic cells
E. Neutrophils
4. When macrophages in the lung are infected with an intracellular bacterium, such as Mycobacterium tuberculosis, they are activated by the interactions of their pattern recognition receptors with the microbe. These activated macrophages will then:
A. Migrate to the marginal sinus of the draining lymph node to activate naive CD4 T cells
B. Increase their phagocytic properties to scavenge dead and dying neighboring cells
C. Migrate to the liver where they will remove dying cells from the blood
D. Migrate to the red pulp of the spleen where they will remove immune complexes from the circulation
E. Up-regulate MHC class II and B7 molecules to amplify CD4 T cell responses in the lung
Explanation / Answer
1. The GIven Sentence is True.
2. The option (B) is correct.
3. The option (D) is correct.
4.The option (A) is correct.
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