What is the mechanism of CTL mediated destruction of infected cells?

What is the mechanism of CTL mediated destruction of infected cells?

Cytotoxic T lymphocytes (CTLs) induce the death of target cells via two distinct and independent mechanisms: the exocytosis of granule components including perforin and granzymes and triggering of the Fas surface receptor.

How do CTL kill target cells?

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.

Which system brings the lysis of target cells on activation?

the immune system
Cell-mediated lysis describes the killing of specific cellular targets by cells of the immune system. The effector cells are most often differentiated CD8+ T cells (that is, cytotoxic T lymphocytes or CTL) or natural killer cells (NK cells).

What is the role of perforin?

Perforin is a glycoprotein responsible for pore formation in cell membranes of target cells. Perforin is able to polymerize and form a channel in target cell membrane. Natural killer (NK) cells and CD8-positive T-cells are the main source of perforin.

What is CTL immunology?

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.

Which pair of molecules is a component of cytotoxic T lymphocyte CTL granules and is important in the mechanism of CTL killing of target cells?

Perforin molecules, as well as several other effector molecules, are contained in the granules of cytotoxic T cells (panel a). When (more…) Both perforin and granzymes are required for effective cell killing.

Does perforin induce apoptosis?

Perforin/granzyme apoptosis pathway is the primary signaling pathway used by cytotoxic lymphocytes to eliminate virus-infected and/or transformed cells. Studies in gene-disrupted mice indicate that perforin, in combination with granzyme, could induce apoptosis.

What leukocyte induces apoptosis using perforin and granzyme?

Key Points. Perforin/granzyme-induced apoptosis is the main pathway used by cytotoxic lymphocytes to kill virus-infected and transformed cells.

How does NK cell recognize the infected cells?

Infected cells are routinely opsonized with antibodies for detection by immune cells. Antibodies that bind to antigens can be recognised by FcγRIII (CD16) receptors expressed on NK cells, resulting in NK activation, release of cytolytic granules and consequent cell apoptosis.

How does the natural killer cell respond if the target cell does not have MHC class I molecules on its surface?

How does the natural killer cell respond if the target cell does not have MHC class I molecules on its surface? It kills the cell by causing pores to form in it.

How does the lysis of target cells via CTL work?

The lysis of target cells via CTL proceeds through a sequence of programmed steps, including killer-target cell binding, delivery of the lethal hit, target cell lysis, and killer cell recycling.

What is the cytotoxic T lymphocyte (CTL) mediated killing mechanism?

FIGURE 1. Schematic presentation of cytotoxic T lymphocyte (CTL)-mediated killing mechanism. Perforin (bars) and granzymes (ovals) are stored together within lysosomes of CTL and secreted via exocytosis in the direction of target cell.

What is the function of CD8 in CTL?

The majority of CTL also bears CD8 molecules, thought to bind reversibly to target cell receptor. Other surface molecules (CD2, CD28, intracellular adhesion molecule) appear to play an important role in activation of CTL following antigen recognition via TCR. CTL are incapable of recognizing free antigens.

How are antigens absorbed by ctctls?

CTL are incapable of recognizing free antigens. Antigens are therefore initially absorbed by specific cells such as dendritic cells and Langerhans cells, which process and present the antigen at their surface along with molecules of the class I major histocompatibility complex (MHC I).