APCs Flashcards
How innate and adaptive immununities interact
antigen presenting cells
Communication Outline
Infection, immune cells phagocytose and present antigen, antigen displayed to T and B cells and T and B cell activation.
Antigen Def
Substance that induces immune response in body. Anything deemed as foreign by immune system (includes altered self - cancer)
Antigen Examples
Foreign microbes (antigens), innocuous peptides (allergens), self-peptides (autoimmune), danger associated molecular patterns (injury) and tumour specific antigens
MHC Receptors
Major Histocompatibility Complex receptors on cell surfaces that trigger T cell activation. 2 Types: MHC 1 and MHC 2
Cells that contain MHC 1
Epithelial cells, macrophage and dendritic cells
Cells that contain MHC 2
Macrophage and dendritic cells
T cells activated by MHC1
CD8 - cytotoxic T cells. Kills cells infected by pathogens (and cancer cells). triggered in response to intracellular infection
T cells activated by MHC 2
CD4 - T helper cells. Help immune response (Th1, Th2 and Th17). Triggered in response to extracellular infection (antigens need to be phagocytosed)
MHC 1 Outline
Intracellular infection. Antigens in cell are broken down by proteases to peptides. peptides are placed in endoplasmic reticulum where they are attached to MHC 1. They are then transported tto cell surface
When are CD8 cells activated to work
When they interact with the specific antigen they’re primed for or when they don’t interact with MHC1
Dendritic Cells Outline
Cells in epithelia and endothelia (skin barrier). APCs and main activator of CD4 cells (most common). Langerhans’s cells = epidermal dendritic cells
How APCs stimulate T cells
Phagocytose external antigens and display antigens on surface. Migrate to lymph nodes where they interact with adaptive immune cells activating them
What molecules are T-cell receptors sensitive to
specififc peptide antigen on APCs MHC 2 receptor
