14 Questions
Which cell type expresses class II MHC constitutively and increases expression with maturation and by IFN-gamma?
Dendritic cells
What principal function is associated with dendritic cells in the context of antigen presentation?
Antigen presentation to naive T cells in the initiation of T cell responses to protein antigens (priming)
Which cell type plays a role in the maturation and selection of T cells in the thymus?
Epithelial cells
Which cell type can present class I MHC–associated peptides to CD8+ T cells?
T cells
What is the principal function of macrophages in the effector phase of cell-mediated immune responses?
Antigen presentation to CD4+ effector T cells
What induces the expression of class 2 MHC in macrophages?
IFN-gamma
What is the effect of TLR ligands on the expression of co-stimulators in macrophages?
Increase expression
In B lymphocytes, what induces the expression of class 2 MHC?
T cell interactions (CD40-CD40L)
What is the principal function of B lymphocytes in humoral immune responses?
Production of antibodies
What is the physiologic role of MHC molecules?
Displaying peptides derived from microbial protein antigens to antigen-specific T lymphocytes
What kind of genes are present in the MHC that code for proteins involved in antigen presentation?
Polymorphic genes
What do MHC molecules explain?
MHC restriction of T cells
3
q
What are MHC genes also known as in humans?
Human leukocyte antigens (HLAs)
Study Notes
Antigen Presentation and MHC Molecules
- Dendritic cells express class II MHC constitutively, and its expression increases with maturation and in response to IFN-gamma.
- Dendritic cells are responsible for processing and presenting antigens to T-cells, activating an immune response.
Thymic T Cell Maturation
- Thymic epithelial cells play a crucial role in the maturation and selection of T cells in the thymus.
Antigen Presentation and T Cells
- Class I MHC-associated peptides are presented to CD8+ T cells by antigen-presenting cells (APCs).
- CD8+ T cells recognize and respond to these peptides, leading to cell-mediated immune responses.
Macrophages in Cell-Mediated Immunity
- Macrophages play a key role in the effector phase of cell-mediated immune responses, where they phagocytose and eliminate pathogens.
- IFN-gamma induces the expression of class II MHC in macrophages, enhancing their antigen-presenting capacity.
- TLR ligands stimulate the expression of co-stimulatory molecules in macrophages, amplifying immune responses.
B Lymphocytes and Humoral Immunity
- IFN-gamma induces the expression of class II MHC in B lymphocytes, enabling them to present antigens to T cells.
- B lymphocytes are central to humoral immune responses, producing antibodies that recognize and eliminate pathogens.
MHC Molecules and Antigen Presentation
- MHC molecules are responsible for presenting antigens to T cells, initiating immune responses.
- The MHC complex contains genes that code for proteins involved in antigen presentation, including class I and class II MHC molecules.
- MHC molecules explain the genetic basis of transplantation rejection and autoimmune diseases.
- In humans, MHC genes are also known as human leukocyte antigens (HLA).
Test your knowledge on the properties and roles of antigen-presenting cells expressing class II major histocompatibility complex (MHC) in initiating immune responses and interacting with CD4+ helper T cells.
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