T cells
Which of the following is the primary site for T cell activation?
Lymph node
True or False. If a foreign antigen is present in high concentration within the thymus as T cells are undergoing differentiation and maturation, the antigen has the possibility of inducing tolerance and, as a result, will not initiate an immune response if seen by T cells in the peripheral lymphoid tissues.
True
True or False After the process of TCR gene recombination, the immature T cell undergoes only one type of selection.
False both positive and negative selection
If the T cell interacts with an MHC:Antigen complex on the surface of a dendritic cell that does not have the second signal (B7 expressed on its surface), what happens?
The T cell undergoes apoptosis because it is likely reacting to a self antigen. This is peripheral clonal deletion of T cells.
What of the following is a primary effector function of the T helper cell?
Activate B cells to promote antibody productions
true or false Naive T cells are made in the Thymus
true
What is the primary difference between activation of T helper cells and T cytotoxic cells?
T helper cells recognize MHC II:Antigen complexes
T cytotoxic cell recognize MHC I:Antigen complexes
What is non-selection?
non-selection refers to T cells that do not bind at all. These cells have nonfunctional TCRs or TCRs to do not react at all with the peptide-MCH complex.
Which of the following is true concerning PD-1 and its action on T cells?
A. PD-1 is Programed Cell Death protein 1. B. PD-1 can inhibit the effector function of both CD4+ and CD8+ T cells C. PD-1 can induce anergy as part of the process of peripheral tolerance D. All of the above are correct.
D. All of the above are correct.
What is the selection process that removes T cells that can’t bind moderately to self antigens presented by the MHC molecules (self peptide-MHC complex) of the thymic epithelial cells?
positive selection
What is the main function of the Tregulatory subpopulation?
They suppress or regulate the immune response. They do this by TGF beta which promotes formation of more Tregs, and IL-10 which suppresses macrophage functions.
Which cytokines are immunosuppressive
IL -10, TGF beta
Which T helper cell subsets is often involved in allergic and parasite reactions?
Th2
What is the selection process that eliminates T cells that have a tight/strong binding to p-MHC complexes on the medullary thymic epithelial cells?
negative selection
True or false
Central tolerance occurs in the secondary lymphoid organs
Central tolerance occurs in the primary lymphoid organs (Thymus in the case of T cells, bone marrow for B cells) during development of the T cells.
Naive T helper cells recognize antigen in the context of which MHC molecule?
MHC II
Which T helper cell subsets activate macrophages via Interferon gamma to markedly enhance killing of phagocytized microbes?
Th1 T cells
What is a probable explanation for the small, dysplastic thymus and lack of identifiable peripheral lymph nodes?
The lack of functional IL-7 will prevent explanation of the T cell populations resulting in lack of T cells throughout the primary and secondary lymph nodes. IL-7 is a primary T cell growth factor.
rationale: A genetic defect in essential cytokines such as IL-7 will result in a defect in T cell production, differentiation, and maturation
T cells need three signals for activation. What are those signals?
Signal one: Recognition of an antigen by the T cell receptor.
Signal two: protein ligand: receptor costimulation (example: B7:CD28 interaction)
Signal Three: release of cytokines that act on the lymphocyte being activated to induce an effector mechanism.
What is the main function of the Th17 subpopulation?
Stimulate an appropriate response to fungi or extracellular bacteria. The naive T helper cell that is stimulated by IL-6 and TGF beta from the dendritic cell will becomes a Th17 cell and recruit neutrophils to the site of infection and stimulate epithelial cells to produce antimicrobial peptides