Cells of the Immune System Flashcards
(35 cards)
What do BM stromal cells do?
provide support and growth factors for HSC maintenance and differentiation
What are the fates of the common myeloid progenitor?
Thrombocytes, Erythrocytes, Mast cells, or
Myeloblast, which gives rise to: Basophils, Eosinophils, Neutrophils, Macrophage, Myeloid dendritic cell
What are the fates of the common Lymphoid progenitor?
Lymphoid dendritic cell, NK cell, T cell, B cell –> Plasma cell
What cytokines are required for myeloid differentiation?
IL-3, GM-CSF
What cytokine is required for Basophil differentiation
IL-4
What cytokine is required for Neutrophil differentiation?
G-CSF
What cytokine is required for Eosinophil differentiation?
IL-5
What cytokine is required for lymphoid differentiation?
IL-7
What cytokine is required for T cell differentiation?
IL-2
What cytokine is required for B cell differentiation?
IL-3
What cytokine is required for monocyte differentiation?
GM-CSF, M-CSF
What is unique about the myeloid family? (are they innate or adaptive?)
ALL THE CELLS OF THE MYELOID LINEAGE ARE INNATE
Describe a myeloid lymphocyte
Comprise most of the innate immune system
First line of defense against a microbial infection
Responsible for presentation of antigen to the adaptive immune system
They are effector cells that can propagate or regulate an established immune response
What is the function of Neutrophils?
Phagocytosis and activation of bactericidal mechanisms
Describe the mechanism of phagocytosis
A pathogen binds to a receptor on a macrophage or neutrophil, which then releases cytokines and inflammatory mediators
The phagocyte then engulfs the pathogen and internalizes it in a phagosome
The phagosome is acidified and fuses with a lysosome
The phagolysosome is filled with antimicrobial enzymes, and the pathogen is degraded (and displayed in the case of APCs)
In addition to phagolysosome formation, what else do Neutrophils do?
release granules of other antimicrobial substances
Primary Granules (azurophilic): Direct toxic/enzymatic activity
Secondary granules (specific): free radical formation
Where are neutrophils generally found, and are they short lived or long-lived?
Neutrophils are most often found in the blood (>70% of WBCs in the blood) but can extravasate into tissues if infected
Short lived –> generally will apoptose after one round of phagocytosis, death can help wall off an infection
In addition to phagocytosis and granule release, how else can neutrophils kill invaders?
NETs (neutrophil extracellular traps)
What are the general functions of Macrophages/Monocytes?
Phagocytosis and activation of bactericidal mechanisms
Antigen presentation
How do macrophages recognize foreign stuff? Is it specific?
Macrophages are innate, so not specific, but have receptors such as TLRs, LPS receptors(CD14), Mannose receptors, glucan receptors, scavengar receptors that help them recognize foreign stuff
What is the general function of dendritic cells?
Antigen uptake in peripheral sites and antigen presentation to naive T cells
Describe the process of a dendritic cell presenting Ag to a T cell
The dendritic cell will recognize a pathogen, phago- or pinocytose it, migrate to a lymph node, and present it to a T cell
What are the general functions of an eosinophil and where are they found?
Killing of Ab coated parasites via granule release
Found in sub-epithelial connective tissue
What are the components of eosinophil granules and what are their functions?
Major basic protein: toxic, stimulate histamine release from mast cells
Eosinophil collagenase: remodels connective tissue matrix
Leukotrienes: smooth muscle contraction, vascular permeability, increased mucus secretion
Eosinophil-derived neurotoxin: helps paralyze pathogen
