Intro Flashcards
What is immunology?
Immunology is a branch of biomedical science concerned with the responses of organisms to immunogenic (antigen) challenges, the recognition of self from non-self, and all the biological (in vivo), serological (in vitro), physical, and chemical aspects of the immune phenomena
where do all cells of the immune system originate from
Hematopoietic cell
what are the two lineages that come from the hematopoietic cells?
Myeloid, Lymphoid
what are the two arms of immune defense
- innate immunity
- Adaptive immunity
what kind of immune response is generated by the innate immune system
nonspecific defense
what kind of immune response is generated from the adaptive immunity
specific defense
which lines of the immune system make up the nonspecific immune response
1st and second line
which lines of defenses makes up the specific defense
3rd
what does the first line of defense consist of?
- skin
- mucous
- membranes
- chemicals
what is the second line of defense made up of
- Phagocytosis
- complement
- interferon
- inflammation
- fever
what is the third line of defense made up of
- lymphocytes
- antibodies
what type of cells are granulocytes and polymorphonuclear leukocytes
-a sub group of white blood cells
what makes granulocytes and polymorphonuclear leukocytes different from other white blood cells/
they are characterized by the presence of cytoplasmic granules
where are granulocytes or polymorphonuclear leukocytes produced
they are produced in the bone marrow
what part of the immune system do the granulocytes and polymorphonuclear leukocytes make up
–innate immunity: first response
how are the cells of the innate immunity/first response classified as
- basophils
- eosinophils
- neutrophils
How does H and E staining effect the naming/classification
they are named as such because of their distinct staining characteristics using H and E histological preparations
how can you distinguish Basophils when looking at them under a microscope
-The granules in the basophils stain dark blue
what are basophils used for
- important for host defense against parasites
- may be involved in allergic inflammatory reactions
what are the granules in basophils and how are they used?
-Basophils contain toxic granules which are used to destroy pathogens during the process of phagocytosis
what is the relation between basophils and adhesion molecules
-basophils express several adhesion molecules which play a critical role in their circulation
which adhesion molecules do basophils express?
- LFA-1 (CD11a/CD18)
- Mac-1 (CD11b/CD18)
- CD44
how do eosinophils stain when looking at them under a microscope
-Eosinophils stain bright red
_______ differentiate from myeloid precursor cells in response to ____, ____, and ______
Eosinophils differentiate from myeloid precursor cells in response to IL-3, IL-5 and GM-CSF
what do eosinophils react to?
chemokines
which chemokines do eosinophils respond to
- CCL5/RANTES
- CCL11/eotaxin-1
- CCL24/eotaxin-2
which cells secrete
- CCL5/RANTES
- CCL11/eotaxin-1
- CCL24/eotaxin-2
- neutrophils
- lymphocytes
how do recruited eosinophils respond
-they release the toxic substances contained in their granules to destroy pathogens and fight infection
how do neutrophils stain in microscopes
-the neutrophilic components in neutrophils stain a neutral pink
which cells are the most numerous innate immune cells?
- Neutrophils
- 50-70% of all white blood cells
what is characteristic of immature neutrophils?
a distinct band-shaped nucleus
how does the band shaped nucleus of immature neutrophils change
-it changes into a segmented nucleus following maturation
where in the body are neutrophils located
- they circulate in the bloodstream
what is the function of neutrophils in the blood stream
-look for foreign objects to phagocytose and degrade
how is the number of circulating neutrophils estimated?
using the absolute neutrophil count
-(ANC)
why might an ANC be high (neutrophilia)
-kidney failure or bacterial infection
what may be the cause of low number of neutrophils (neutropenia)
-leukemia or bone marrow damage
what is the risk associated with neutropenia
an increased risk of infection
how can granulocytes be identified in their immature state
expression of CD16, CD34
how can granulocytes be identified in their active state?
expression of CD11b/CD18
Activated basophils can be identified by
- CD13/Aminopeptidase N
- CD107a/LAMP1
- CD164
Activated eosinophils can be identified by
- CD44
- CD69
- IL-5
Activated neutrophils can be identified by
- CD16
- L-selectin (CD62L)
where are mast cells generated?
in the bone marrow
what are mast cells similar to?
basophilic leukocytes
what do mast cells and basophilic leukocytes have in common
-CD34+ precursor cells
what are the two types of mast cells
- connective tissue mast cells
- Mucosal mast cells
what are connective tissue mast cells responsible for
-local allergic reaction
what are mucosal mast cells responsible for
- they are found in areas of the body that are exposed to the external environment
- (I.E. lung mucosa, digestive tract, mouth and nose)
what is the activated function of mast cells
-release of granules containing histamine and active agents
what are mast cells important for
defense against parasites
what can mast cells found in tissues be used for
-mediate allergic reactions by releasing inflammatory mediators like histamine
where are monocytes/macrophages found
-they are found in the blood stream and in tissues
how do monocytes circulate through the body
-they circulate in the peripheral blood befor entering tissue to replenish tissue specific macrophage populations
(osteoclasts, microglia, histiocytes, Kupffer cells)
What are macrophages named for
- Greek: Big eater
- named for their ability to ingest and degrade bacteria
upon activation, _______ and ______ coordinate an immune response by notifying other immune cells of existing infection
upon activation, Monocytes and Macrophages coordinate an immune response by notifying other immune cells of existing infection
what is the macrophages interaction with lymphocytes
-macrophages can present antigens to lymphocytes
what is the important non immune function of macrophages?
-recycling dead cells such as red blood cells
what is another name for these non immune functions of macrophages
-Housekeeping functions
do these house keeping functions need the immune system to be activated
no the housekeeping functions occur without activation of the immune response
______ are innate immune cells
-Natural killer cells are innate immune cells
can NK cells have featrures of both innate and adaptive immunity?
yes some subpopulations of NK cells have features of both innate and adaptive immunity (I.E. NKT cells)
What is the primary function of Natural killer cells
-they recognize and kill virus-infected cells or tumor cells
how do NK cells function
they contain granules, which are filled with proteins that can form holes in the target cell and also cause apoptosis
apoptosis:
programmed cell death
what is the other function of NK cells other than their function as cytolytic effectors
-they are also regulators of immune response
what are Dendritic cells
-specialized sentinel cells
where do DC cells interact with antigens
-the specialized sentinel cells constantly sense and respond to their immediate environment
where are DC cells derived from
all DC are hematopoietic bone marrow derived cells
where do DC cells mature
- the bone marrow
- lymphoid tissue
- non-lymphoid tissue
what is the primary function of DC cells?
-DCs capture, process, and present antigens to T cells and thus are crucial for bridging innate and adaptive immunity as well as promoting sel-tolerance
what are DC cells function after exposure and uptake of pathogens
-Maturing DC travel to secondary lymphoid organs where they become potent T cell activators
DCs are classified as
- classical/conventional dendritic cells (cDCs)
- Plasmacytoid dendritic cells (pDCs)
pDCs have the ability to secrete large amounts of ________ upon activation through TLR7 and TLR9
-type 1 interferons
what part of the immunity are lymphocytes B lymphocytes (b cells) part of
-are an essential component of the humoral immune response (adaptive immunity)
Where do B cells mature?
B cells mature in the bone marrow
where do b cells mature in avian species
-In birds b cells mature in the bursa of fabricius
When are B cells activated?
when they bind antigens through their receptors (BCR)
What are B cells responsible for?
B cells are responsible for generating antibodies to specific antigens
how do antibodies interact with pathogens
-antibodies coat the surface of a pathogen
what three roles do antibodies serve
- neutralization
- opsonization
- complement activation
Neutralization:
occurs when the pathogen is covered in antibodies and cannot further infect host cells
Opsonization:
an antibody-boud pathogen serves to alert immune cells such as neutrophils and macrophages, to engulf and digest the pathogen
Complement activation:
is a process for directly destroying or lysing pathogens
can complement components act as opsonins?
yes they can opsonize pathogens
what is another name for t cells
t lymphocytes
which antigen specific receptor do T cells express
TCR
what is the precursor to T cells (lymphocytes)
thymocytes
thymocytes develop from:
Hematopoietic stem cells in the bone marrow
where do thymocytes move to to mature
the thymocytes move to the thymus to mature
While in the thymas what happens to ensure the maturation results in a functional t cell
- stages of selection
- Quality control
T cells are an essential component of the___________
-cellular immune response
which two groups are t cells divided into
- CD8+
- CD4+
how are t cells differentiated into CD8+ and CD4+ cells
-it is based on which co-receptor protein is present on the cell surface
CD8+ T cells AKA
- cytotoxic T cells
- cytotoxic T lymphocytes (CTLs)
What is the function of CD8+ cells
they recognize and kill infected or cancer cells
How do CTLs kill target cells
CTLs have cytotoxic granules, containing cytotoxins that kill target cells
what are the 4 major CD4+ T cell subsets
- TH1
- TH2
- TH17
- T regulatory cells
TH refers to:
T helper cells
What is the function of Th1 cells
-coordinate immune responses against intracellular pathogens
what does Th1 cells secret and what is the function of those secretions
-Th1 cells secrete molecules (cytokines) that alert and activate other immune cells, like bacteria-ingesting macrophages
Th2 cells coordinate immune response against:
extracellular pathogens (I.E. helminths)
how do Th2 cells coordinate immune responses against extracellular pathogens
-by alerting B cells, granulocytes, and mast cells
What ar Th17 cells named for
Th17 cells are named for their ability to produce interleukin 17
Interleukin 17 (IL-17) function
-functions as a signalling molecule that activates immune and noon immune cells
Th17 cells function
-to protect surface (skin, gut) against extracellular bacteria (recruitment of neutrophils)
Tregs: or Regulatory T cells: function
monitor and inhibit the activity of other T cells
how do immune cells communicate
through cell to cell contact or secreted signalling molecules
what is fundamental for cellular communication
- Receptors
- ligands
what are receptors
-protein structures
may be expressed on the surface or intracellular compartments of cells
Ligands:
are the molecules that activate receptors
are ligands free floating or membrane bound?
both
how would altering the expression and density of various receptors and ligands affect the immune response
-this allows the immune cells to dispatch specific instructions tailored to the situation at hand
what is the function of cytokines
-small proteins with diverse function such as cell growth, activation etc
where can toll-like receptors be found
innate immune cells such as:
- macrophages
- DC
what is the function of TLRs
TLRs recognize general microbial patterns and they are essential for innate immune cell activation and inflammatory response
B cell receptors (BCRs) and T cell receptors (TCRs) location/function
- expressed on b cells and t cells respectively
- Function: they recognize foreign antigens
MHC:
Major histocompatibility complex
MHC function
as carriers to present antigens on cell surfaces
MHC proteins also signal
whether a cell is a host cell or a foreign cell
Complement are:
a series of proteins found in the blood
the complement functions to
literally punches small holes into the pathogen, creating leaks that lead to cell death
Complement proteins also serve as signalling molecules that:
- alert immune cells
- recruit immune cells to inflammatory sites
