[W9] T cell phenotypes Flashcards
(28 cards)
What do CD4+ T cells recognise?
Peptides presented by MHC class II
CD4+ T cells primarily interact with MHC class II molecules found on professional antigen-presenting cells.
What do CD8+ T cells recognise?
Peptides presented by MHC class I
CD8+ T cells are essential for recognizing infected or cancerous cells through MHC class I.
What are the three required signals for T cell activation?
TCR + MHC:peptide, Co-stimulation (e.g., CD28/B7), Cytokines from dendritic cells
These signals ensure T cells are properly activated and can respond effectively.
What proteins make up the CD3 complex?
γ, δ, ε, ζ chains (δε, εγ, ζζ dimers)
The CD3 complex plays a crucial role in T cell receptor signaling.
Which kinases are involved in early TCR signalling?
Lck, Fyn, and Zap-70
These kinases are critical for transducing signals from the T cell receptor.
What signalling motifs do CD3 proteins contain?
ITAMs (immunoreceptor tyrosine-based activation motifs)
ITAMs are essential for initiating T cell activation upon antigen recognition.
What cytokines promote Th1 cell development?
IL-12 and strong antigen stimulation
Th1 cells are important for cell-mediated immunity.
What do Th1 cells secrete and what do they activate?
IFN-γ, IL-2, TNF-α → activate macrophages
Th1 cells enhance the ability of macrophages to eliminate intracellular pathogens.
What promotes Th2 differentiation?
IL-4 and low levels of antigen
Th2 cells are crucial for humoral immunity and responses to parasites.
What do Th2 cells help with?
B cell activation, class switching, eosinophils, and mast cells
Th2 cells facilitate the body’s response to extracellular pathogens.
What transcription factor defines Treg cells?
FoxP3
FoxP3 is essential for the development and function of regulatory T cells.
What is the function of Treg cells?
Suppress immune responses, promote tolerance
Treg cells are vital for maintaining immune homeostasis and preventing autoimmunity.
Which cytokines induce Th17 cells?
TGF-β and IL-6
Th17 cells are important for defense against extracellular bacteria and fungi.
What do Th17 cells secrete and recruit?
IL-17, which recruits neutrophils
Th17 cells play a key role in promoting inflammation and recruiting immune cells.
How do Th1 cells help macrophages?
Secrete IFN-γ → activates killing mechanisms
This activation enhances the macrophages’ ability to destroy pathogens.
How do Th2 cells help B cells?
Via CD40L-CD40 interaction and cytokines (IL-4, IL-5) for class switching and plasma cell formation
Th2 cells are essential for antibody production and class switching in B cells.
What aids focused cytokine delivery between Th and B cells?
Adhesion molecules and Golgi/cytoskeleton polarisation
This ensures effective communication and activation between T and B cells.
How do CD4+ T cells support CD8+ T cells?
Activate dendritic cells, promote co-stimulatory molecule expression, enhance memory formation
CD4+ T cells are crucial for the optimal activation and function of CD8+ T cells.
What is required for CD8+ T cell priming?
Strong co-stimulation in lymph nodes, often with CD4+ T cell help
Effective priming is essential for the subsequent cytotoxic response of CD8+ T cells.
Do CD8+ T cells need co-stimulation to kill?
No – once activated, they kill targets without co-stimulation
This allows for rapid response to infected or malignant cells.
What are the two main cytotoxic mechanisms used by CD8+ T cells?
Perforin/granzyme → induces apoptosis, Fas/FasL interaction → triggers apoptosis
These mechanisms are critical for the elimination of infected or cancerous cells.
What cytokine do CD8+ T cells secrete to limit viral spread?
IFN-γ
IFN-γ also has immunoregulatory roles and enhances the activity of other immune cells.
What ensures macrophage activation is controlled?
Requires antigen-specific CD4+ T cell help to prevent bystander damage
This mechanism prevents unnecessary tissue damage during immune responses.
What determines the T cell phenotype outcome?
Antigen strength and density, Co-stimulatory molecule expression, Cytokine environment from dendritic cells
These factors collectively shape the immune response and T cell differentiation.
