18 Questions
Which of the following cytokines is NOT involved in the differentiation of Th17 cells?
IFN-γ
What is the primary function of Th2 cells?
Providing help for B cells
Which type of T cell is involved in suppressing stimulatory activity of APCs?
Treg
What is the primary function of CD8+ T cells?
Killing target cells
Which cytokine is involved in the differentiation of Th1 cells?
IFN-γ
What is the role of TGF-β in the differentiation of Treg cells?
Inducing the differentiation of Treg cells
Which cells display peptides in the context of highly polymorphic MHC molecules?
APCs
What is required for the activation of T cells?
Two signals
What is the primary function of CD8 T cells?
To recognise and kill virus-infected or cancerous cells
What is required for the activation of CD4 T cells?
Two signals, one from the T cell receptor and one from a co-stimulatory molecule
What is the function of MHC class I molecules?
To present antigens to CD8 T cells
What is the result of T cell receptor genes undergoing rearrangements?
The creation of a highly diverse repertoire of T cell receptors
What is the function of co-stimulatory molecules such as CD28 and CD86?
To provide the second signal for T cell activation
What is the difference between MHC class I and II molecules?
MHC class I molecules present antigens to CD8 T cells, while MHC class II molecules present antigens to CD4 T cells
What is the result of the interaction between the T cell receptor and MHC molecules?
The recognition of peptides by T cells
What is the characteristic of T cell receptors?
They are composed of two chains joined by disulphide bonds
What is the function of antigen-presenting cells (APCs) such as monocytes, macrophages, and dendritic cells?
To present antigens to T cells
What is the result of the activation of CD4 T cells?
The activation of macrophages and the production of cytokines
Study Notes
T Cell Antigen Recognition
- Peptides are displayed by cells in the context of highly polymorphic MHC molecules.
- MHC molecules are highly polymorphic, with MHC I and II having different structures and functions.
- MHC I is expressed on all nucleated cells, associates with β2 microglobulin, and is endogenously expressed.
- MHC II is expressed on specialized antigen-presenting cells (APCs), including monocytes, macrophages, dendritic cells, and B lymphocytes.
Sources of Peptides Loaded into MHC Class I and II
- MHC class I is loaded with peptides from viral proteins and endogenous proteins.
- MHC class II is loaded with peptides from exogenous antigens.
T Cells Recognise Peptides with Their T Cell Receptors
- T cells are defined by expression of the T cell receptor (TCR), which is a membrane-bound heterodimer.
- TCR consists of two chains (α and β) joined by disulfide bonds, with variable and constant domains.
- TCR genes undergo rearrangements from germline before translation.
Two Main Classes of ab T Cell
- CD8+ T cells (cytotoxic T cells) recognise peptides presented by MHC I.
- CD4+ T cells (helper T cells) recognise peptides presented by MHC II.
Activation of T Cells Requires Two Signals
- Signal 1: TCR recognises peptide-MHC complex.
- Signal 2: Co-stimulation by CD28 and CD86, which is upregulated on APCs by danger signals (infection, inflammation).
CD8 T Cells: Cytotoxic Lymphocytes (CTL)
- CD8+ T cells are cytotoxic cells that can kill target cells, such as virus-infected cells or cancerous cells.
Activated CD4 Cells Can Differentiate into Different Kinds of Effector T Cells
- CD4+ T cells can differentiate into different types of helper T cells, including Th1, Th2, Th17, and Treg cells.
- Each type of helper T cell has distinct functions, such as producing different cytokines and providing help to different cells.
CD4+ T Cell Subsets
- Th1 cells: produce IFN-γ and IL-2, help activate CD8+ T cells and macrophages.
- Th2 cells: produce IL-4, IL-5, and IL-13, help activate B cells.
- Th17 cells: produce IL-17, IL-21, and IL-22, help fight extracellular pathogens.
- Treg cells: produce TGF-β and IL-10, suppress immune responses.
This quiz covers the topics of innate immune protection, antibody and lymphocyte diversity, T cells, MHC, tolerance, and T cell effector functions in immunology lectures 2-5.
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