Innate Immunity Flashcards
What cells are important in innate immunity?
Neutrophils, macrophages, dendritic cells, natural killer cells
What positively charged antimicrobial peptides are maintained in epithelial cells and neutrophils?
Defensins
The innate immune response displays what two types of barriers?
Physical & chemical
How do innate immune cells recognize pathogens and become activated to carry out their numerous functions?
Pattern Recognition Receptors (PRRs) on innate cells non-specially recognize pathogen-associated molecular patterns (PAMPs) on pathogens.
What are the three types of PRRs on innate cells and where are they located?
C-type lectin receptors - extracellular
TLRs - intracellular/extracellular
NOD-Like receptors - intracellular/cytoplasmic
Carbohydrates are recognized by what PRR?
C-type lectin receptors
What TLR recognizes LPS on G- bacteria?
TLR-4
What TLRs are located extracellularly?
TLR-1, TLR-2, TLR-4, TLR-5, TLR-6
TLR-1, TLR-2, and TLR-6 recognized what ligands?
Peptidoglycan and lipoproteins on G+
What TLR recognizes flagellin?
TLR-5
What TLRs recognize viruses?
TLR-3 - dsRNA
TLR-7, TLR-8 - ssRNA
CpG DNA in bacteria are recognized by which TLR?
TLR-9
What cytokines increase inflammation and enhance the innate immune response?
TNF, IL-1. IL-6, IL-12
What cytokines are released by macrophages?
IL-1, IL-6, IL-8, IL-12, TNF alpha
IL-12, which is released by macrophages, serves what role?
Activates NK cells
What cytokine released by macrophages recruits neutrophils?
IL-8 (CXCL-8)
Which cytokines induce fever?
IL-1, IL-6
What is the function of IL-1?
Activation of the endothelium & lymphocytes. Also induces fever
What is the function of TNF alpha?
Activation of the epithelium and increase of vascular permeability
What cytokine triggers local containment of infection, but may cause shock when released systemically?
TNF alpha
What is the process by which leukocytes enter tissues from the blood?
Leukocyte Rolling & Migration
What receptors are present on macrophages, neutrophils, and dendritic cells that enable phagocytosis?
Complement receptors & Fc receptors
What enzymes are used by phagocytes for phagocytosis?
NADPH oxidase - reactive oxygen species
& inducible nitric oxide synthase (iNOS) - reactive nitrogen species
Where are MHC I receptors expressed? What is their function?
Expressed on all nucleated cells to present antigens to CD8 T Cells
What cells display MHC II receptors? What is their function?
Present on professional phagocytes and antigen-presenting cells to present antigens to CD4 T cells
Neutrophils phagocytize pathogens using reactive oxygen species. If a pathogen is catalase +, how will that affect phagocytosis?
Catalase breaks down H2O2 so there will be a decrease in pathogen vulnerability to phagocytosis by neutrophils
How do macrophages differ from neutrophils?
Neutrophils - exist in blood, short-lived, first responders, phagocytosis by ROS, extracellular traps
Macrophages - exist in tissues, longer-lived, phagocytosis by NOS, cytokine release, antigen presentation, ingestion of necrotic host cells
How does the function of dendritic cells differ from that of neutrophils and macrophages?
Dendritic cells phagocytize pathogens for the purpose of antigen presentation to T cells.
How are virus-infected cells primarily killed?
By Natural Killer cells
How are NK cells activated?
Activation receptors - antibody-coated cells, lectins, viral hemagglutinins
Inactivation receptors - MHC I
A cell expresses less MHC I on the surface than typical. What might this be indicative of? What is the body’s response?
Viral-infected and tumor cells express less MHC I than normal cells. NK cells recognize lower levels of MHC I expression and phagocytize the cell.
How do phagocytes phagocytize pathogens?
The phagocyte ingests the pathogen in a phagosome. The phagosome and lysosome undergo phagolysosomal fusion. The pathogen is degraded in the phagolysosome by degrative enzymes that were stored in the lysosome.
What are the primary pattern recognition receptors (PRRs) of PAMPS?
C-type lectin receptors, TLRs, NOD-like receptors
Where are the PRRs located?
C-type lectin - extracellular
TLRs - extracellular & intracellular
NOD-like receptors - cytoplasm & intracellular