Innate Immunity Cells Flashcards
Myeloid lineage cells
All RBCs, granulocytes, monocytes, and macrophages
What are the functions of the WBCs that emerge from the myloid lineage cells?
- Respond rapidly to the invasion of a pathogen and attempt to repel the invaders themselves
- Release molecules (cytokines) that alert other immune cells to danger, induce vasodialation to increase blood flow to the area, and activate other immune cells (locally and distally)
Granulocytes
- contain granules
- multilobed nuclei
-Include neutrophils, eosinophils, basophils, and mast cells
Granules
Membranebound internal vesicles that release their contents in response to an infection (filled with bio-active antimicrobial peptides/proteins)
Function to directly damage pathogens, regulate trafficking and activity of other WBCs and contribute to tissue repair
Neutrophil
- First responders, most abundant class of granulocytes in the blood
- Express a broad variety of PRRs (increases versitility through linking with host receptors)
- Recruited to the site of infection in response to chemoattractant molecules
- Circulating neutrophils sense endothelial layers at inflammatory sites and attach at these locations, slow down and enter the tissue via extravasion
- Functions to help in tissue remodelling, directly harms pathogens, regulates proteases, and induced vasodialation and inflammation
Eosinophils
- Rare in blood (1-3%) and abundant in the small intestine/ resp tract
- Eosinophil PRRs result in the release of cytokines including IL-1, IL-6, and chemokine CXCL8; these will increase blood flow to the tissue and attract other leukocytes (makes endothelial cells more permeable to WBCs
- Functions to induce ROS formation, vasodialtaion, and basophil degranulation, aids in antiviral activity, modulates adaptive immune responses, and attracts leukocytes
- They bind to IGE and aide in parasite destruction
- release NETs
- the granule contents can cause allergy and asthma symptoms
Basophil/ mast cells
- basophils are rare in blood (<1%) and mast cells reside in perpheral tissues
- basophils express PRRs through which they can become activated to secrete cytokines like IL-4 and IL-13 which promote at type 2 cellular response. They also release CCL3 which recruits other leukocytes
- Functions to regulate inflammation, modulates adaptive immunity and induces vasodialation and smooth muscle activation
- release NETs and play a role in parasitic immunity
- when activated they can secrete TND-alpha and IL-4 which help drive innate and adaptive immune responses
- contribute to allergy symptoms
What are the 3 types of cytokine action?
Autocrine: cytokines activate the cell that released them (same cell)
Paracrine: cytokines activate a nearby cell
Endocrine: cytokines enter circulation and target distant cells from their original “creator”
Cytokines
Master regulators of the actions of the immune system. Include chemokines, colony stimulating factors, interferons, interleukins, transforming growth factor, and tumour necrosis factor.
How do activated neutrophils directly destroy pathogens?
Phagocytosis, extending NETs (Neutrophil extracellular traps), and generate ROIs (reactive oxygen intermediates)
Profesional antigen presenting cell (pAPC)
a cell with the capacity to activate T lymphocytes; includes monocytes, macrophage, dendritic cells, and B cells (important cellular bridge between innate and adaptive immunity)
What makes a pAPC “professional”?
They are able to presnet antigenic peptides in both MHC class I and MHC class II 9recodnized bt helper T cells) as well as they co-express costimulatory ligands necissary for T cell stimulation
What are the 3 major activities of the pAPCs when they encounter pathogens?
- Secrete proteins that attact and activate other immune cells
- Internalize pathogens via phagocytosis and present these peptide antigens on their surface using MHC class II molecules
- Upregulate costimulatory molecules required fo optimal activation of T helper cells
Describe the process of what happens after a APC recodnizes a foreign molecule/ infected cell.
- Phagocytosis of enemy cell/ antigen
- Fusion of lysosome and phagosome
- Enzymes start to degrade enemy cell
- Enemy cell broken into small fragments
- Fragments of antigen is presented on the APC surface
- Leftover fragments are released by exocytosis
Monocyte
- have cellular components: nucleus, lysosome, and phagosome
- constitute 2-12% of circulating WBCs
- a heterogenous group of cells that migrate into tissues and differenciate into a diverse array of tissue-resident phagocytic cells; they regulate inflammatory responses at site of tissue damage and infection
- 2 main types: inflammatory and patrolling
