Immune System - Lecture 1 Part B Flashcards
Where are all blood cells produced?
The bone marrow
Which stem cells do all blood cells come from?
Hematopoietic stem cells
What causes a Hematopoietic stem cell to differentiate into a specific blood cell?
Signals the the cell receives from the microenvironment
What can Hematopoietic stem cells differentiate into?
Myeloid Progenitor or a Lymphoid Progenitor
What cells do Myeloid Progenitors give rise to?
All the blood cells except lymphocytes •RBCs •Basophils •Neutrophils •Eosinophils •Monocytes •Macrophages
What do Lymphoid Progenitor give rise to?
- Natural killer cells (NK cells)
- T lymphocytes
- B lymphocytes
What do Granulocytes have in their cytoplasm?
Granules
Which cells are Granulocytes?
- Neutrophils
- Eosinophils
- Basophils
- MAST cells
What is another name for Neutrophils?
Polymorphonuclear leukocytes
Why are Neutrophils also called Polymorphonuclear leukocytes?
Because their nucleus is multileveled
What are the most abundant Granulocytes?
Neutrophils
Which Granulocytes are the first to arrive at the site of an infection?
Neutrophils
How do Neutrophils get to the site of an infection?
The migrate from the blood to the infected sites
What do Neutrophils do once they arrive at the site of an infection?
They start Phagocytosis of the pathogen or antigen
When do numbers of Neutrophils especially increase?
During a bacterial or fungal infection and acute inflammation
How long do Neutrophils live for?
One or two days
When do Eosinophil numbers increase?
During parasitic or worm infections. They also play a role in allergic reactions
How do Eosinophils fight worms?
They cluster around them and release granules through degranulation that kill the pathogen
What receptors are Eosinophils rich in?
IgE receptors
What is IgE?
The antibody that is increased during parasitic infection
When does Degranulation occur in Eosinophils?
When IgE from a parasite binds to it receptors
Where are Eosinophils mainly found?
The GI tract, the lungs, and urinary and genital mucosa and in the skin
What do Eosinophils release other than Granules?
Cytokines and Chemokine
What do Cytokines and Chemokines released by eosinophils do?
During Inflammatory response recruit other cells to the site of an infection
Why does the level of Eosinophils in the blood drastically increase?
To respond to infection
What do Basophils have in their cytoplasm?
Granules
Which Granulocytes are rare in blood?
Basophils
Which Granulocytes are very Potent?
Basophils
What is the mean of killing of Basophils?
Degranulation but they do not phagocytize after killing
When are Basophils used?
During parasitic and allergic infections as well as reactions
What do Basophils also release aside from Granules?
Histamines
Which Granulocyte releases histamines?
Basophils
What do Histamines do?
They increase vascular permeability and blood flow to the area facilitating the migration of other immune cells
Which Granulocytes have heparin in their granules?
Basophils
Where are Mast cells usually found?
In our skin and mucosal tissues
When are Mast cells important?
During parasitic infections and allergic reactions
What do the Granules of Mast cells contain?
Histamine
What it responsible for the common symptoms during an allergic reaction?
Histamine
What cells produce lipid mediators?
Mast cells
What are some lipid mediators?
Prostaglandins and other cytokines
What do Lipid Mediators do?
Help during inflammation activating other cells to fight against a pathogen
What are the three antigen presenting cells?
Monocytes, Macrophages and dendritic cells
What are Antigen presenting cells?
Cells that ingest and digest the antigen and present it to lymphocytes initiating an immune response
What is a monocyte called once it migrates from the blood to the tissues?
A macrophage
What is the lifespan of Macrophages?
A long time
What do Macrophages do besides Phagocytosis?
Produce a lot of cytokines that help recruit other cells and regulate the immune response
Which cell helps with tissue repair post-infection and post-inflammation?
Macrophages
How do Macrophages help post-infection and post-inflammation?
They phagocytize dead cells and garbage that remain post infection and stimulate the production of collagen
How do dendritic cells facilitate trapping a pathogen?
By their long projections of the cytoplasm that help them to phagocytize the pathogen
What do Dendritic cells do after Phagocytizing a pathogen?
They migrate to the secondary lymph organs
How do Dendritic cells trap pathogens?
Through their projections and Phagocytosis
What do Natural Killer cells do?
Fight intracellular pathogens and find tumor cells and prevent their growth
Why are NK cells considered to be a self-made immune response?
Because they don’t have receptors for specific antigens and don’t generate memory
How do NK cells recognize their targets?
Through MHC1 a protein shared among several cells
How do NK cells kill?
Through apoptosis or programmed cell death
How do NK cells work?
They recognize abnormal MHC1 in cells that are infected or tumours and induce their death. They also have cytotoxic granules
What chemical do NK cells produce and what does it do?
Interferon Gamma and it activates macrophages and enhances their phagocytic activity
What does Interferon Gamma do?
Activates macrophages and enhances their phagocytic activity
What do T lymphocytes become once they are activated?
Helper T-cells or Cytotoxic cells
How do T-Cytotoxic cells fight against intracellular infection?
They induce apoptosis of infected cells and generate memory
Why are T and B cells known as Adaptive immune responses?
Because they create memory
What does it mean for T cells to only be able to recognize processed antigens?
They can only be activated if the antigen that is presented to them is presented by an antigen presenting cells like macrophages or dendritic cells that also have MHC molecules
Which antigens do T cytotoxic cells recognize?
Those bound to MHC1 complexes
Which antigens do T helper cells recognize?
Those bound to MHC2 molecules
What type of antigens do B cells recognize?
Unprocessed antigens (those that have not been processed by other cells like macrophages)
What is interesting about B-lymphocytes?
They can also be antigen presenting cells and present to T cells, especially T helper cells to activate them to produce antibodies
What are the Mediators of the Humoral immune response?
B lymphocytes
