29 Questions
What is the main reason for the massive T-cell activation and release of large amounts of cytokines caused by superantigens?
They polyclonally activate a large fraction of T cells
Why do microbial antigens need to be transported to lymph nodes despite T cells mainly being present in lymphoid organs?
To enhance the chances of encounter with T cells
Which of the following is a characteristic of conventional T-dependent antigens compared to superantigens?
Recognition by a small fraction of T cells leading to monoclonal/oligoclonal response
What is the primary function of superantigens produced by some pathogenic viruses and bacteria?
Acting as a defense mechanism against the immune system
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
What is the mechanism of uptake by immature dendritic cells?
Pinocytosis of liquid or small granule
Which mechanism leads to the uptake of exogenous antigens through Fc receptor mediation?
Phagocytosis
What is the purpose of antigen processing in relation to T cell recognition?
Degrade antigens into short peptide sequences for T cell recognition
Which antigen presentation pathway involves MHC class II molecules?
Exogenous antigen processing
Where does the association of peptides with MHC molecules occur during antigen processing?
Endoplasmic reticulum
What is the role of APCs in antigen presentation?
Activate T cells via T cell receptors and MHC molecules
What is the main function of MHC class I molecules?
Regulation of immune responses to intracellular parasites
Which cell types are included in the group of Professional Antigen Presenting Cells (APC)?
Macrophages, dendritic cells, and B cells
Why is the distribution of MHC class II expression restricted to Antigen Presenting Cells (APCs)?
Because only APCs can uptake extracellular antigens
What is the role of T cells in responding to antigens?
Being presented antigenic peptides by APCs
Which feature is characteristic of peptides binding to MHC molecules?
Low affinity and broad specificity binding
What is the primary determinant of tissue graft acceptance or rejection?
MHC molecules on the cell surface
Which type of antigens are generated within cells due to normal cell metabolism or intracellular infections?
Endogenous antigens
Which of the following is an example of endogenous antigen?
Infected human cells
What is the function of superantigens?
Cause excessive activation of the immune system
Which antigens are recognized by the immune system in patients with autoimmune diseases?
Autoantigens
What is the function of histocompatibility antigens?
Help in tissue compatibility for transplants
What is the main purpose of antigen transport to the lymph node?
To interact with T cells
Which class of antigens results in massive cytokine release due to polyclonal T cell activation?
Superantigens
During antigen uptake, where do the antigens enter mainly?
Cytoplasm of cells
What occurs during the process of antigen degradation?
Partial breakdown of antigens into peptides
Why is it essential for immature dendritic cells (DCs) to migrate to draining lymph nodes?
To start processing presenting the antigen to T cells
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
Which statement best describes antigen presentation to T cells?
Expressing peptide-MHC complexes on cell surfaces for T cell recognition
Explore the concept of endogenous antigens that are generated within cells due to normal cell metabolism or infections like viruses. Learn about human tissue antigens including blood group antigens (A, B, Rh), histocompatibility antigens (MHC, HLA), and cells infected with viruses.
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