Lecture 11 9/21/23 Flashcards
What happens to viral infected cells?
killed by cytotoxic T cells
What happens to tumor/abnormal cells?
killed by cytotoxic immune cells (cytotoxic T cells, NK cells, etc)
Why is cell-mediated immunity important for intracellular pathogen elimination?
antibodies are unable to reach pathogens inside of cells
What receptors are present on the surface of cytotoxic T cells?
-CD3
-CD8
-TCR
-LFA-1
-PRRs
How do LFA-1 and ICAM-1 play a role in cytotoxic T cell function?
-cytotoxic T cells have LFA-1 on surface
-target cells have ICAM-1 on surface
-LFA-1 and ICAM-1 adhere T cells to their target cells
How do DCs indirectly activate cytotoxic T cells?
-DCs activate Th1 cells
-Th1 cells activate CD8 T cells
What do CD8 T cells do once fully activated?
-leave the lymphoid organs
-seek out infected cells by themselves
What do T cells do once they recognize an antigen?
induce the target cell to undergo apoptosis
What are the two pathways utilized by cytotoxic T cells to kill target cells?
-perforin pathway
-fas pathway
What are the characteristics of the perforin pathway?
-CD8 T cells target cells presenting abnormal peptides on MHCI
-CD8 T cell releases perforin and granzymes
-apoptosis is induced in viral infected cells and some tumor cells
What is the role of perforin?
to polymerize on the target cell membrane and form a pore/channel into the cell
What is the role of granzymes?
to enter the cell through the perforin pore and induce apoptosis
What are the characteristics of the fas pathway?
-T cell surface protein Fas-ligand binds to target cell death receptor Fas
-targets tumor cells, unwanted T cells, and autoimmune T cells
What type of infection are NK cells and other phagocytic cells involved in, from a cytotoxicity standpoint?
viral infections and other intracellular infections
What are the characteristics of NK cells?
-target cells that fail to present MHCI and/or have abnormal cell surface proteins
-line of defense against viruses and tumors
-contain perforin and granzymes
