Antigen Presenting Cells Quiz

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Questions and Answers

Which type of cell is primarily responsible for the activation of naive T cells?

Macrophages

B cells

Non-professional APCs

Dendritic cells (correct)

What characteristic is unique to professional antigen-presenting cells?

Constitutive expression of MHC class I molecules

Weak antigen-presenting capacity

Constitutive expression of MHC class II molecules (correct)

Inducible expression of MHC class II molecules

How do professional APCs present exogenous antigens?

By direct contact with T cells

Through MHC class I molecules

By ingesting and processing the antigens (correct)

Using antibodies bound to the antigens

Which cells are categorized as non-professional antigen-presenting cells?

Endothelial cells Signup and view all the answers

What is a functional characteristic of plasmacytoid dendritic cells (pDC)?

Produce large amounts of type I interferons when activated Signup and view all the answers

What is the main function of antigen-presenting cells (APCs) in the immune system?

Processing antigen and presenting it to T cells Signup and view all the answers

Why are dendritic cells considered the most effective APCs?

They can activate naive T cells efficiently Signup and view all the answers

Which class of MHC molecules is responsible for presenting endogenous antigens?

MHC class I Signup and view all the answers

What distinguishes traditional APCs from non-professional ones in terms of their ability to stimulate T cells?

Traditional APCs express co-stimulatory signals and MHC molecules consistently. Signup and view all the answers

What types of antigens are presented by MHC class I molecules?

Endogenous antigens Signup and view all the answers

Which antigen-presenting cell (APC) is known for its high constitutive expression of MHC class II molecules?

Dendritic cells Signup and view all the answers

How does B cell antigen presentation primarily occur?

Using antigen-specific receptors (BCR) Signup and view all the answers

What is the primary function of APCs in the immune response?

To activate T cells Signup and view all the answers

What distinguishes exogenous antigens from endogenous antigens?

Exogenous antigens come from outside the cell Signup and view all the answers

Which pathway is responsible for presenting endogenous antigens to CD8+ T cells?

MHC class I pathway Signup and view all the answers

Which type of antigen-presenting cell is most effective for activating naive T cells?

Dendritic cells Signup and view all the answers

In terms of co-stimulatory molecules, how do macrophages compare to B cells?

Macrophages have inducible expression of co-stimulatory molecules. Signup and view all the answers

Which of the following antigens is processed through the MHC class II pathway?

Bacterial toxins engulfed by APCs Signup and view all the answers

What is a characteristic of B cells in relation to their antigen presentation capabilities?

B cells can present antigens at low concentrations. Signup and view all the answers

What is the primary characteristic of immature dendritic cells (DC)?

Strong antigen uptake and processing ability Signup and view all the answers

Which factor is essential for immature dendritic cells to migrate to peripheral lymphoid organs?

Specific chemokine receptor expression like CCR7 Signup and view all the answers

What distinguishes mature dendritic cells from their immature counterparts?

Increased ability to induce T cell activation Signup and view all the answers

What is a primary function of dendritic cells in the immune response?

Process and present antigens to T cells Signup and view all the answers

During the migration phase, what changes occur in immature dendritic cells?

Expression of specific chemokine receptors Signup and view all the answers

Which of the following statements about antigen presenting cells (APCs) is accurate?

Mature DCs have a higher affinity for processing exogenous antigens than immature DCs. Signup and view all the answers

What role do inflammatory cytokines play in the maturation of dendritic cells?

They promote the transition from immature to mature dendritic cells. Signup and view all the answers

How do dendritic cells contribute to immune tolerance?

By secreting cytokines that inhibit T cell activation Signup and view all the answers

Which cells are considered a type of immature dendritic cells specifically found in the skin?

Langerhans cells Signup and view all the answers

Study Notes

Antigen Presenting Cells (APCs)

APCs are immune cells that process and present antigens to T cells, activating them and initiating immune responses.
APCs play a crucial role in immune recognition, response, and regulation.

Types of APCs

Professional APCs (pAPCs) constitutively express MHC II molecules and co-stimulatory molecules, enabling strong antigen presentation. Examples include dendritic cells (DCs), monocytes/macrophages, and B lymphocytes.
Non-professional APCs express MHC II molecules inducibly, exhibiting weaker antigen presentation capabilities. Examples include endothelial cells, fibroblasts, and various epithelial and stromal cells.

Dendritic Cells (DCs)

DCs are the most potent professional APCs, capable of activating naive T cells.
Immature DCs exhibit strong antigen uptake and processing capabilities with weak antigen presentation functions.
Mature DCs have reduced antigen uptake and processing but enhanced antigen presentation capabilities. They express numerous dendritic-like projections.

Migration and Maturation of DCs

Immature DCs migrate from the bone marrow to various tissues, such as the skin and mucosa.
Immature DCs, upon encountering antigens or inflammatory stimuli, express specific chemokine receptors and migrate through lymphatic vessels and/or blood circulation to peripheral lymphoid organs, transitioning to migratory DCs.
Migratory DCs further mature into mature DCs in peripheral lymphoid organs, characterized by high expression of MHC II molecules, co-stimulatory molecules, and adhesion molecules.

DCs Biological Functions

DCs possess various biological functions essential for immunity:
- Recognition and uptake of antigens, participating in innate immune responses.
- Processing and presentation of antigens, initiating adaptive immune responses.
- Immunoregulatory functions: secrete cytokines and chemokines.
- Induction and maintenance of immune tolerance: thymic DCs induce central immune tolerance, while immature DCs can induce peripheral immune tolerance.

Monocytes/Macrophages

Monocytes/macrophages are phagocytic cells that engulf and degrade pathogens.
They can present antigens to T cells, contributing to both innate and adaptive immunity.
They are classified into bone marrow pre-monocytes, peripheral blood monocytes, and macrophages.

B Cells

B cells are important for antibody production.
They can also act as APCs by presenting antigens to T cells.
B cells constitutively express MHC II molecules at low levels, effectively presenting antigens to CD4+ T helper cells even at low concentrations.

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Description

Test your knowledge on Antigen Presenting Cells (APCs) and their types. This quiz covers professional and non-professional APCs, focusing on the roles of dendritic cells in immune response. Understand how these immune cells activate T cells and their importance in immune regulation.