CTL Function and Mechanisms

The video tutorial covers CD8+ T cells, focusing on their development, activation, and mechanisms of action. CD8+ T cells, or cytotoxic T lymphocytes (CTLs), recognize targets through T-cell receptors and MHC class I molecules. They develop in the thymus and circulate as naïve cells until activated. The CTL response involves activation, contraction, and memory phases. CTLs kill target cells via perforin/granzyme-mediated lysis or death receptor-induced apoptosis. The video also discusses antigen presentation, cytokine production, and the role of memory cells in immune response.

What is the primary role of CD8+ T cells in the immune system?

• To produce antibodies

• To suppress immune responses

• To recognize and destroy infected or cancerous cells

• To activate B cells

Where do naïve CD8+ T cells circulate?

• Between peripheral lymphoid organs

• In the bone marrow

• In the central nervous system

• Only in the bloodstream

Which receptor is highly expressed by naïve CD8+ T cells for lymph node homing?

• CCR5

• CD62L

• CXCR4

• CD28

What are the three phases of the CTL response to an acute infection?

• Activation, contraction, and memory maintenance

• Recognition, proliferation, and apoptosis

• Infiltration, expansion, and resolution

• Migration, differentiation, and suppression

Which type of memory CTL is found in non-lymphoid tissues?

• Tissue-resident memory cells

• Central memory cells

• Effector memory cells

• Naïve T cells

What is cross-presentation in the context of CTL activation?

• Presentation of exogenous antigens by APCs

• Direct presentation of antigens by infected cells

• Presentation of antigens by B cells

• Activation of CTLs without antigen presentation

Which cytokine is primarily produced by antigen-stimulated CTLs?

• TGF-β

• IL-4

• IFN-γ

• IL-10

What is the role of perforin in CTL-mediated cytotoxicity?

• To bind to antigens

• To form pores in target cell membranes

• To inhibit apoptosis

• To activate B cells

Which pathway involves the Fas/FasL interaction in CTL cytotoxicity?

• Complement-mediated lysis

• Death receptor-induced apoptosis

• Perforin/granzyme pathway

• Antibody-dependent cellular cytotoxicity

What is the function of TRAIL in CTL activity?

• To induce apoptosis in target cells

• To promote cell proliferation

• To enhance antibody production

• To suppress T cell activation