Module 2 Lecture 3: Leukocytes Flashcards
What are leukocytes and an example of what can be a leukocyte?
WBCs; they are the mobile units (some immobile) of the immune system; complement proteins (alpha and beta globulins) are an example
Immune system contains: leukocytes, leukocyte derivatives, plasma proteins and immune organs
Other than recognizing and destroying foreign materials, what other functions do leukocytes play?
- defends against invading pathogens (i.e. bacteria and viruses)
- Clean-up crew: removes worn out-cells (aged RBCs) & cleans tissue debris (damaged by trauma or disease), wound healing and tissue repair
- Identifies and destroys cancer cells arising in the body
- Seek out and attack strategy
Seek out and attack lets them move to site of invasion or damage; hence why they are in blood (to quickly go from site of production to where they are needed)
What does the structure of leukocytes look like? What are they classified into?
Colourless (lacking Hb so stained with dye to see)
* 5 Types of circulating Leukocytes with 2 categories: Polymorphonuclear granulocytes & mononuclear agranulocytes
Bigger than RBCs & some immune cells don’t primarily circulate in blood
How do Neutrophils work?
Phagocytic specialists; destroy bacteria intracellularly
* Release extracellular fibre webs (NETS) that use bacteria-killing chemicals
Polymorphonuclear granulocytes (many shaped nucleus with granules)
granules stained with neutral dye (hence neutrophils)
How do Eosinophils work?
Only attacks parasites covered in antibody via granule content
* Only follow the instructions of the immune system; releases contents if the parasite has specific antigen
* Increase in eosinophils means allergic conditions such as asthma as well as parasite infections
Polymorphonuclear granulocytes
Granules are stained red for acidic
How do Basophils work?
Chemotactic factor production
* Synthesises and Stores histamine and heparin
* Least number and poorly understood (controls immune responses to parasite)
Polymorphonuclear granulocytes
Granules are stained with basic dye; histamine is used for allergic reactions and heparin speeds up the removal of fat particles from blooc
How do monocytes work?
Phagocytosis, cytokine production, antigen presentation & cytotoxicity
* While immature; emerge from bone marrow and circulate for 1-2 days in blood before going into tissue
* Enlarge in tissue => macrophages
* Dies from phagocytosis but lasts longer than neutrophils
Mononuclear agranulocytes (single nucleus lacking granules)
Other immune function = produces cytokines to signal other immune cells. Also tissue resident macrophages release cytokines to do the same thing
What are some functions of Macrophages?
- Eats up dead neutrophils
- Eats cellular matrix, pathogens, and debris that were destroyed
- Sends signals to fibroblasts to rebuild ECM and tissue
Fibroblasts secrete the proteins found in the ECM
How do large granular lymphocytes work?
Two types; one has granules contrary to being agranulocytic
Large granular lymphocytes => NK cells
* Cells of innate immune response
* Extremely effective on virally infected cells
* Releases lytic granules
* Cytokines made to limit viral replication
NK cells kill any cell that refuses show its “ID”
Which lymphocytes are adaptive?
B lymphocytes and T lymphocytes
How do B cells work?
**Can fully differentiate into plasma cells and make antibodies in the ER
* Recognizes the antigen and marks it (does not destroy the pathogen)
Anti-body mediated immunity - releases antibodies but does not kill via itself
How do T cells work?
Cell-mediated immunity
* Two functions: Act like NK cells and also commands other cells
* Destroys targets via releasing chemicals that punches holes through them.
Do not produce antibodies unlike b cells; they themselves go and attack
