Studied by 4 people
Define: Extracellular
Site of infection is outside of cells (blood, lymph, epithelial surfaces)
Define: Intracellular
Site of infection inside of cells (cytoplasmic or vesicular)
Define: Humoral Immunity
Related to the earliest efforts to understand immunity, belief that health is controlled by fluids, if the fluids are out of balance it less to disease.
Modern definition: Immunity mediated by soluble molecules
What were the four humors?
Blood, Phlegm, Bile (yellow bile), Stool (black bile)
Explain von Behring's contributions to Humoral immunity
He observed that fluids transferred from one inoculated animal could provide protection to another, even to a lethal dose of bacteria.
Explain Jules Bordet's contributions to Humoral immunity
Demonstrated two components of humoral immunity:
Heat stable, and specific for whatever the animal was immunized to
Heat-liable, non-specific anti-microbial activity
Explain Paul Ehrlich's contributions to humoral immunity
Define the components discovered by Bordet:
Component 1 were proteins produced by cells, expressed on cell surface and released into blood (antibodies - adaptive)
Component 2 was non-specific blood component that complemented the antibodies (complement - innate)
What mediates humoral immunity?
B cells (antibodies) and Complement. Pathogens are covered in antibodies so that they cannot replicate, then complement pokes holes in bacteria and lyses them.
Define: Complement
Approximately 40 soluble proteins that can bind to and activate in the presence of microbial cell surfaces. Activation leads to proteolytic cascade that results in the generation of the MAC (membrane attack complex), which creates pores and lyses the target.
Explain the characteristics of complement
Little specificity and no memory (one complement protein the same as the next, secondary responses do not improve)
NOT responsible for protective immunity observed in serum transfers
Define: Antibodies
Highly pathogen-specific side-chains produced by B-cells
How are humoral and cellular immunity related? Give an example that involves antibodies
Antibodies (humoral) are made by B-cells (cellular). Additionally B-cells often need help from T-cells (cellular) to make antibodies.
Name three functions of antibodies
Neutralization Opsonization Complement activation
What is Humoral Memory comprised of?
Long-lived circulating antibodies Long-lived plasma-cells (B-cells) that continue to secrete antibodies or memory B-cells
Explain Metchnikoff's contributions to our understandings of cellular immunity
Observed that cells from sea urchins were able to absorb and internalized particulate matter, first described phagocytosis (cells eating bacteria). Birth of cell-mediated immunity
Explain Miller's contributions to our understandings of cellular immunity
Proposed subsets of lymphocytes, named antibody producing cells in bone marrow B-cells and lymphocytes from the thymus T-cells
Which lymphocytes are produced in bone marrow?
B-cells
Where are T-cells created, do they mature in the same place?
T-cells are created in bone marrow, however unlike B-cells they mature in the thymus
Explain Pross's contributions to our understandings of cellular immunity
Identified Natural Killer cells (NK cells) from the spleen that can kill cells without prior exposure. These cells maintained their killing even after the depletion of B and T cells.
Define: Cellular immunity, name components of cellular immunity
Cell-mediated immune response, responsible for clearance of virally infected cells, intracellular bacteria and tumors. Consists of involves phagocytes, granulocytes, T-cells, B-cells, and NK cells
How does cellular immunity kill targets?
Phagocytosis Neutrophil degranulation Modulation of cellular activity Direct killing of infected cells
How do T-cells and Natural Killer cells differ?
T-cells can't recognize a pathogen directly, they rely on innate immune cells to present the pathogens to the T-cell. Only after activation are T-cells able to kill the target.
NK cells don't need to do this, they kill without aid from the innate immune system.
Define: Neutralization
Antibodies prevent bacterial adherence by coating pathogen
Define: Opsonization
Antibodies promote phagocytosis by coating pathogen with specific antibodies for phagocytes to target
Define: Complement activation
Antibodies activate complement, which enhances opsonization and lyses some bacteria (very efficient)
True or False: Antibodies are effective against all forms of bacteria
False, antibodies are ineffective against intracellular bacteria as antibodies cannot perform their functions within cells.
Define: Phagocytosis
Neutrophils or macrophages consume pathogen (extracellular)
Define: Neutrophil Degranulation
Neutrophils release toxins around pathogen (extracellular)
Define: Modulation of Cellular Activity
TH1 cells signal infected cells to increase levels of digestive enzymes to consume pathogen within, does not kill cell.(intracellular)
Define: Death Receptors
CD8+, T-cells, and NK cells signal death receptors, cell self-lyses. (intracellular)
Define: Cytotoxic Granules
CD8+, T-cells, and NK cells release toxins directly on affected cell, killing cell and pathogen within. (intracellular)
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