Introduction to the Immune System Flashcards
Define humoral immunity.
The immune responses mediated by soluble effector molecules (Abs)
What are the roles of phagocytes?
To kill microorganisms via phagocytosis or secretion of factors.
What are the roles of mast cells, basophils, and eosinophils?
Defense against multicellular parasites. Also plays a pathogenic role in allergy.
What are the roles of natural killer (NK) cells?
Elimination of infected and malignant cells via apoptotic mechanisms.
What is C-reactive protein’s (CRP) role in the immune system?
A type of acute phase protein and opsonin that binds to the C protein of pneumococci and promotes phagocytosis.
What are the 3 main functions of components of the complement system?
- Lyse bacterial species
- Attract phagocytes to the site of the infection (chemotaxis)
- Opsonization of bacteria for phagocytosis
What is the difference between cytokines and chemokines?
Cytokine is a general term used for all signaling molecules. Chemokines are specific cytokines that function by attracting cells to sites of infection/inflammation.
What is the difference between B and T lymphocytes?
- B cells contain B-cell receptors (BCR) that bind a specific antigen. Once bound, the cell differentiates into plasma cells where it will secrete Abs. Part of humoral immune response.
- T cells contain T-cell receptors (TCR) that also bind to specific antigens. Once bound, the cell controls the cell-mediated immune response. Does not secrete Abs.
Explain how to antigen presenting cells (APCs) work and give examples.
They contain surface molecules called major histocompatibility complexes (MHC) that present to T cells.
Examples: macrophages, dendritic cells, and B cells
What are the two kinds of fixed elements in the immune system? Give examples.
Primary: Bone marrow, thymus
Secondary: Spleen, lymph nodes, mucosal immune tissues
What kind of stem cells are the components of the innate and adaptive immunity derived from?
Hematopoietic Stem Cells (HPC)
What is the difference between the products of the Lymphoid lineage vs the Myeloid lineage?
Lymphoid lineage produces B and T cells. Myeloid cells produce everything else for the immune system.
What does G-CSF stimulate the production of?
First Myeloblasts, then Granulocytes: neutrophils, basophils, and eosinophils.
What does M-CSF stimulate the production of?
First Monoblasts, then Monocytes: dendritic cells, macrophages
What controls differentiation of lymphoid progenitors into mature B cells and T cells?
Interleukin 7 (IL-7)
What kind of cells are neutrophils, eosinophils, basophils, and mast cells?
Granulocytes and Polymorphs (nucleus has multiple compartments)
How does a monocyte become a macrophage?
When it leaves the blood and enters the tissue where the infection is occurring.
What kind of immune cell is exclusively found in tissue?
Mast cell
How are B cells, T cells, and NK cells differentiated from each other?
Using antibodies that recognize specific antigens, termed Cluster of Differentiation (CD).
What are the key CD marker(s) found exclusively on T cells?
CD3, CD4, and CD8
What are the key CD marker(s) found exclusively on B cells?
CD19 and CD20
What are the key CD marker(s) found exclusively on NK cells?
CD56
What are the key CD marker(s) found exclusively on Macrophages/Monocytes?
CD14
What are the two main types of phagocytes? What is the difference between the two?
Neutrophils and macrophages. Macrophages have a “scavenger function” to get rid of damaged tissue.
What are the most abundant cells of the immune system?
Neutrophils
What are defensins?
Small cysteine-rich cationic proteins which act against bacteria, fungi, and many enveloped viruses.
What is the “left shift” seen during leukocytosis?
Seen during inflammation/infection. When the bone marrow is producing more WBCs, namely neutrophils, and releasing them into the blood before they are fully mature.
What is a third way (besides phagocytosis and granule release) that neutrophils attack pathogens?
Releasing Neutrophil Extracellular Traps (NETs). NETs are comprised of DNA, proteins, and enzymes. NETs can either directly kill the pathogen or pull it in for phagocytosis.
Describe how most long-lived resident macrophages come about.
Derived from hematopoietic progenitors emerging in the yolk sac. Then fulfill tissue-specific functions depending on the organ.
What are the functions of inflammatory macrophages?
Contribute to inflammatory reactions and tissue remodeling that repairs “collateral damage” produced by hypersensitivity reactions.
What is the difference between myeloid DCs (mDCs) and plasmacytoid Dcs (pDCs)?
mDCs: derived from monocytes, similar to tissue macrophages.
pDC: subset of interferon-producing DC that circulates blood and peripheral tissues, unknown developmental origin.
What are Langerhans cells (LCs)?
A subpopulation of DCs that reside in the epidermis of the skin. After antigen activation, the become potent APCs.
What is the key role of mast cells, basophils, and eosinophils?
Innate immune response against helminths (multi cellular parasites). They also account for allergic and anaphylactic reactions.
Describe the granules found in mast cells and basophils.
Contains histamine, serotonin, heparin, cytokines, and chemokines. Stained with basic dye.
Describe the granules found in eosinophils.
Large secondary granules: contains four basic proteins
Small granules: histamine, peroxidase, lipase, and major basic protein
Both stained with neutral dye
What is the most common form of mastocytosis?
Urticaria Pigmentosa
Where do NK cells undergo differentiation?
In the bone marrow
How do NK cells work?
They recognize antigens normally expressed on host cells. The absence of that antigen activates the NK cells.
What is the difference between cytotoxic T cells and NK cells?
NK cells are part of the innate immunity. Cytotoxic T cells are part of the adaptive immunity.
What is the difference in roles between T helper cells and cytotoxic T lymphocytes (CTLs)?
T helper cells activate macrophages to kill phagocytized microbes. CTLs directly destroy infected cells.
