Chapter 5: Activation of T cells Flashcards
What type of microbes are phagocytosed?
- intracellular bacteria
- fungi
- protozoa
What type of microbes infect nonphagocytic cells?
- viruses
- rickettsiae
- protozoa
Effector T cells encounter antigens and what action occurs?
- leukocyte activation (inflammation)
- phagocytosis and killing of microbes
- CTL killing of infected cell
What are the steps in activation of T lymphocytes?
- antigen recognition
- cytokine secretion
- proliferation
- differentiation
- effector functions
What are the effector functions of T cells?
CD4+ = activation of macrophages, B cells, other cells
CD8+ = killing of infected “target cells”; macrophage activation
After differentiation of T lymphocytes do they become effector T cells or memory T cells?
both
Signal transduction for Class II MHC is via CD4 or CD8?
CD4
Signal transduction for Class I MHC is via CD4 or CD8?
CD8
What ligand allows for T cell adhesion?
LFA-1
LFA-1 is an ______ protein
integrin
- for adhesion
ICAM-1 is a _______
ligand for adhesion
What is the costimulation from the antigen presenting cell to the T cell to activate it?
B7
What happens if MHC binds from cell to T cell but there is no costimulator?
no response
When MHC binds and the antigen presenting cell is activated what is secreted?
B7 costimulator
cytokines (IL-12 or 2)
_________ receptors are necessary for limiting/terminating immune responses
Inhibitory
What ligand/receptor combo is necessary for activation of T cell?
B7
CD28
APCs that engulf virus infected cells and also are infected themselves will have antigens presented by…
both class I and II MHC molecules
What ligand allows for proliferation of T cells?
IL-2R
Signal transduction pathways in T lymphocytes involve a lot of…
phosphorylation and dephosphorylation
What is the space between the APC and T cell called?
immunological synapse
What do the drugs cyclosporine and rapamycin do?
interfere with the signal transduction pathways in T cells
- used in transplant patients to prevent rejection
What is the principle function of IL-2?
survival and proliferation of antigen-specific T cells
What is the antigen and costimulator required for T cell activation?
CD28
B7
What is the affinity difference between a T cell with IL-2RByc and IL-2RaByc?
low affinity - IL-2RByc
high affinity - IL-2RaByc
What causes the difference between IL-2RByc and IL-2RaByc on the T cell?
IL-2 secretion
T follicular helper cells remain where?
in lymphoid organ and migrate to the follicles
Effector T cells and antibodies enter circulation and go to…
sites of infection
CD4+ T cells activate…
macrophages - killing of phagocytosed microbes
B cells - secretion of antibodies
How do CD4+ T cells activate macrophages and B cells?
CD40L and cytokines
S1P is required for naive T cells or Activated T cells?
both
What T cell homing receptors are required for naive and effector T lymphocytes?
selectin
integrin
chemokine receptor
What are the T cell homing receptors for naive T cells?
L-selectin
LFA-1
CCR7
