T Cells Activation Polarization Flashcards
What are the three signals required for T cell activation?
Signal 1: Antigen recognition via TCR and MHC interaction.
Signal 2: Costimulatory signal via CD28 and B7 interaction.
Signal 3: Cytokine signaling to drive differentiation.
What is the role of IL-2 in T cell activation?
IL-2 promotes T cell proliferation and differentiation into effector cells.
What are the major subsets of CD4+ T cells?
Th1 (intracellular pathogens, macrophage activation)
Th2 (extracellular parasites, B cell activation, IgE production)
Th17 (mucosal immunity, inflammation, neutrophil recruitment)
Treg (immune regulation, suppression of immune response)
What factors influence T cell polarization?Cytokine environment, antigen dose, TCR binding strength, and type of pathogen.
Cytokine environment, antigen dose, TCR binding strength, and type of pathogen.
What is T cell anergy?
Anergy is a state of unresponsiveness in T cells caused by lack of costimulatory signals.
CD4+ T cells recognize antigens presented on
MHC class II molecules.
CD8+ T cells recognize antigens presented on
MHC class I molecules.
Th1 cells produce IFN-γ and TNF-α to activate
macrophages and enhance cellular immunity.
Th2 cells produce IL-4, IL-5, and IL-13 to promote
humoral immunity.
CTLA-4 competes with CD28 to
downregulate T cell activation.
T cell activation requires only antigen recognition.
False
CD4+ and CD8+ T cells require different MHC molecules for activation.
True
Th1 cells are involved in allergic responses.
False – Th2 cells mediate allergic responses.
Tregs suppress immune responses and prevent autoimmunity.
True
The primary cytokine responsible for T cell proliferation is ______________.
IL-2
Th1 cells are important for defense against ______________ pathogens.
Intracellular
The absence of costimulatory signals leads to T cell ______________.
Anergy
CD8+ T cells differentiate into ______________ T lymphocytes.
Cytotoxic
Which cytokine promotes Th2 differentiation?
a) IFN-γ
b) IL-4
c) TNF-α
d) IL-17
Answer: (b) IL-4
Which costimulatory molecule is required for full T cell activation?
a) CTLA-4
b) CD28
c) IL-10
d) FasL
Answer: (b) CD28
Which T cell subset is involved in neutrophil recruitment and inflammation?
a) Th1
b) Th2
c) Th17
d) Treg
Answer: (c) Th17
A patient with a viral infection has increased CD8+ T cell activity. What process is occurring?
CD8+ T cells are recognizing viral antigens on MHC class I and differentiating into cytotoxic T lymphocytes.
A person with a helminth infection shows high levels of IgE. Which T cell subset is likely dominant?
Th2 cells, which promote IgE production and eosinophil recruitment.
A patient with an autoimmune disorder shows defective regulatory T cells. What might be happening?
Lack of Treg-mediated suppression could be leading to excessive immune activation and autoimmunity.
T Cell Activation:
The process by which T cells recognize antigens and receive signals to proliferate and differentiate.
T Cell Polarization:
The differentiation of CD4+ T cells into distinct subsets (Th1, Th2, Th17, Treg).
Costimulation:
A secondary signal required for full T cell activation, provided by CD28-B7 interaction.
Cytokines:
Soluble proteins that regulate immune responses and T cell differentiation.
Anergy:
A state of unresponsiveness in T cells due to the absence of costimulation.
