Endogenous Antigens in Human Cells

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What is the main reason for the massive T-cell activation and release of large amounts of cytokines caused by superantigens?

They activate only a small fraction of T cells in the immune response

They polyclonally activate a large fraction of T cells (correct)

They enhance acquired immunity by promoting memory T-cell formation

They are produced by viruses and bacteria to evade the immune system

Why do microbial antigens need to be transported to lymph nodes despite T cells mainly being present in lymphoid organs?

To prevent T-cell activation

To enhance the chances of encounter with T cells (correct)

To stimulate memory T-cell formation

To increase the microbial antigen concentration in the blood

Which of the following is a characteristic of conventional T-dependent antigens compared to superantigens?

Production by pathogenic viruses and bacteria

Recognition by a small fraction of T cells leading to monoclonal/oligoclonal response (correct)

Release of large amounts of cytokines causing systemic toxicity

Polyclonal activation of a large fraction of T cells

What is the primary function of superantigens produced by some pathogenic viruses and bacteria?

Acting as a defense mechanism against the immune system Signup and view all the answers

Why do T cells need microbial antigens to be captured, processed, and presented in a specific way for interaction?

To enable T cells to interact with complex microbial antigens Signup and view all the answers

What is the mechanism of uptake by immature dendritic cells?

Pinocytosis of liquid or small granule Signup and view all the answers

Which mechanism leads to the uptake of exogenous antigens through Fc receptor mediation?

Phagocytosis Signup and view all the answers

What is the purpose of antigen processing in relation to T cell recognition?

Degrade antigens into short peptide sequences for T cell recognition Signup and view all the answers

Which antigen presentation pathway involves MHC class II molecules?

Exogenous antigen processing Signup and view all the answers

Where does the association of peptides with MHC molecules occur during antigen processing?

Endoplasmic reticulum Signup and view all the answers

What is the role of APCs in antigen presentation?

Activate T cells via T cell receptors and MHC molecules Signup and view all the answers

What is the main function of MHC class I molecules?

Regulation of immune responses to intracellular parasites Signup and view all the answers

Which cell types are included in the group of Professional Antigen Presenting Cells (APC)?

Macrophages, dendritic cells, and B cells Signup and view all the answers

Why is the distribution of MHC class II expression restricted to Antigen Presenting Cells (APCs)?

Because only APCs can uptake extracellular antigens Signup and view all the answers

What is the role of T cells in responding to antigens?

Being presented antigenic peptides by APCs Signup and view all the answers

Which feature is characteristic of peptides binding to MHC molecules?

Low affinity and broad specificity binding Signup and view all the answers

What is the primary determinant of tissue graft acceptance or rejection?

MHC molecules on the cell surface Signup and view all the answers

Which type of antigens are generated within cells due to normal cell metabolism or intracellular infections?

Endogenous antigens Signup and view all the answers

Which of the following is an example of endogenous antigen?

Infected human cells Signup and view all the answers

What is the function of superantigens?

Cause excessive activation of the immune system Signup and view all the answers

Which antigens are recognized by the immune system in patients with autoimmune diseases?

Autoantigens Signup and view all the answers

What is the function of histocompatibility antigens?

Help in tissue compatibility for transplants Signup and view all the answers

What is the main purpose of antigen transport to the lymph node?

To interact with T cells Signup and view all the answers

Which class of antigens results in massive cytokine release due to polyclonal T cell activation?

Superantigens Signup and view all the answers

During antigen uptake, where do the antigens enter mainly?

Cytoplasm of cells Signup and view all the answers

What occurs during the process of antigen degradation?

Partial breakdown of antigens into peptides Signup and view all the answers

Why is it essential for immature dendritic cells (DCs) to migrate to draining lymph nodes?

To start processing presenting the antigen to T cells Signup and view all the answers

What is the main difference in membrane protein expression between immature and mature DCs?

Immature DCs express receptors for microbial binding, mature DCs express MHC molecules Signup and view all the answers

Which statement best describes antigen presentation to T cells?

Expressing peptide-MHC complexes on cell surfaces for T cell recognition Signup and view all the answers