How does a cytotoxic T lymphocyte CTL kill a cell infected with a virus?

How does a cytotoxic T lymphocyte CTL kill a cell infected with a virus?

Cytotoxic T cells kill their targets by programming them to undergo apoptosis (Fig. 8.35). When cytotoxic T cells are mixed with target cells and rapidly brought into contact by centrifugation, they can program antigen-specific target cells to die within 5 minutes, although death may take hours to become fully evident.

Do cytotoxic T cells kill APCs?

CD4+ T cell-mediated killing of major histocompatibility complex class II-positive antigen-presenting cells (APC). CD4+ cytotoxic T cells induce apoptosis of APC.

What do CTL cells do?

Cytotoxic T lymphocytes (CTLs) represent one of several types of cells of the immune system that have the capacity to directly kill other cells. They play a major role in host defense against viral infection, as well as infection by other intracellular pathogens that replicate in the cytoplasm of the host cell.

Why are antigen presenting cells not killed?

Professional APC can avoid from being killed by CD8 because it is mainly located in lymph node where there are only naive and central memory CD8 which has much less effector function.

What methods do cytotoxic T TC cells use to destroy infected cells?

Cytotoxic T Cells CTLs are able to kill target cells directly by inducing apoptosis. Nucleases and other enzymes activated in the apoptotic process may help destroy the viral genome, thus preventing the assembly of virions and potential infection of other cells.

How do T cells kill infected cells?

When the perfectly shaped virus antigen on an infected cell fits into the Killer T-cell receptor, the T-cell releases perforin and cytotoxins. Perforin first makes a pore, or hole, in the membrane of the infected cell. Cytotoxins go directly inside the cell through this pore, destroying it and any viruses inside.

How do cytotoxic T cells kill a level?

CTLs kill target cells directly by inducing apoptosis. They release preformed perforins at the target cell surface to generate transmembrane pores in the target cell, through which a second set of proteins and granzymes gain entry into the cytosol to initiate an apoptotic series of events.

How do helper T cells and cytotoxic T cells work together?

How do helper T-cells and cytotoxic T-cells work together? Helper T-cells produce cytotoxic T-cells. Cytotoxic T-cells produce cytokines to activate helper T-cells. Helper T-cells produce cytokines to activate other cells of the immune system.

Do antigen-presenting cells get destroyed?

Antigen-presenting cells show digested antigens to T cells through the MHC on their surface, which allows the T cell to “see” the antigen and recognize it as foreign. The connection between the MHC and the receptor on the T cell is the first signal necessary to activate the T cell to respond to a tumor and destroy it.

Are antigen-presenting cells destroyed?

Cytotoxic T cells destroy virus-infected cells in the cell-mediated immune response, and helper T cells play a part in activating both the antibody and the cell-mediated immune responses. Antigen fragments will then be transported to the surface of the APC, where they will serve as an indicator to other immune cells.

Why does APC activate naive CTL when the antigen is present?

By choosing this way, APC can activate naive CTL which will kill all cells which present this antigen. See references 1 and 2 for more details. This pathway is important for the immune response to a number of viruses as well as tumors which evade the MHCII mediated immune response by suppressing the MHCII antigen presentation.

What is the function of antigen presenting cells?

ANTIGEN-PRESENTING CELLS Antigen-presenting cells (APC) are cells that can process a protein antigen, break it into peptides, and present it in conjunction with class II MHC molecules on the cell surface where it may interact with appropriate T cell receptors.

Does CD8 kill APC?

Professional APC can avoid from being killed by CD8 because it is mainly located in lymph node where there are only naive and central memory CD8 which has much less effector function. However, what about non-professional APC?

What are maternal antigen-presenting cells (APCs)?

Maternal antigen-presenting cells (APCs), consisting of macrophages and dendritic cells (DCs), are scattered throughout the decidua. Macrophages constitute 20–30\% of the decidual cells at the site of implantation and remain constant during pregnancy (Mor and Abrahams 2003 ).