Immune exam review

What is immunology?

the study of the immune system, immune response, and molecular mechanisms that help defend against microbial attacks or other foreign substances.

the immune system protects against…

pathogens (viruses, bacteria, protists, fungi, and parasites), cancer cells, and cells of differentiated blood types

define immune response

collective and coordinated response to the introduction of foreign substances

define the immune system

a system of cells, tissues, and their soluble products that recognize, attack, and destroy foreign entities that endanger health.

the ___ is the central player in maintenance of homeostasis and human health

immune system

malfunctioning of the immune system may result in…

autoimmune diseases, transplant rejection, hypersensitivity and allergy, immunodeficiency.

[transition of immunology into experimental science, role of modern molecular bio]

present at birth, highly nonspecific, no immunological memory, most evolutionarily conserved arm of the immune system

innate immunity

highly specific, activated after exposure to pathogens and acquired during one’s lifetime, highly specific and retains immunological memory

adaptive/acquired immunity

which immunity is only present in vertebrates?

acquired/adaptive immunity

what are the three phases of the host immune defense? just list

1. Non-induced, non-specific innate responses

2. induced innate responses

3. specific adaptive immune response

the innate response of immune defense involves ___ defense barriers. (give examples)

primary. ex: skin, epithelial barriers, mucous membranes, salivary enzymes, lacrimal secretions, pH

phagocytosis, target cell lysis, inflammatory responses, and complement action are all parts of which phase of innate immunity?

induced innate responses

specific adaptive immune response involves ___ and ___

B-lymphocytes and T-lymphocytes

along with epithelial barriers, ___ cells are major components of the innate immune response

phagocytic cells

what are epithelial barriers in immunity?

the major interfaces between the body and the external environment that provide physical and chemical barriers (defensins) against infection- skin, GI tract, respiratory tract, genitourinary tract.

The two types of circulating phagocytes, ___ and ___, are blood cells that are recruited to sites of infection, where they recognize and ingest microbes for intracellular killing

neutrophils and monocytes

the most abundant leukocytes in the blood. these cells ingest microbes in the circulation and rapidly enter extravascular tissues at sites of infection, where they also phagocytose and destroy microbes.

neutrophils

neutrophils are also called

polymorphonuclear leukocytes (PMNs)

during inflammatory reactions, these cells enter extravascular tissues and differentiate into cells called macrophages.

monocytes

blood ___ and tissue ___ are two stages of the same cell lineage, which is often called the ___ system

monocytes, macrophages. mononuclear phagocyte system

these cells function as sentinels in tissues that respond to microbes by producing numerous cytokines, which serve two main functions: they initiate inflammation, and they stimulate adaptive immune responses

dendritic cells

dendritic cells capture ___. why?

protein antigens. they display fragments of these antigens to T cells (antigen presenting cells)

these cells recognize infected and stressed cells and respond by killing these cells and secreting interferons (macrophage-activating cytokine).

natural killer cells

describe how natural killer cells induce cell death.

they secrete perforin, a protein that creates pores in the target cell’s membrane. Unregulated diffusion of ions and molecules through the pores causes osmotic imbalance, causing swelling and rupture of infected cell.

the complement system is a collection of ___ that are important in ___

membrane-associated proteins, defense against microbes

complement activation culminates in…

the formation of a polymeric protein complex (membrane attack complex) that inserts into the microbial cell membrane, disturbing the permeability barrier and causing osmotic lysis

tissue reaction that delivers mediators of host defense—circulating cells and proteins—to sites of infection and t issue damage.

inflammation

describe the steps producing inflammation

1. bacteria introduced at wound site. activated macrophages engulf the pathogens and secrete cytokines and chemokines

2. mast cells in the area are activated by the tissue damage and release histamine

3. histamine and cytokines dilatate local blood vessels and increase their permeability. The cytokines also make the vessel wall sticky, causing neutrophils and monocytes to attach.

4. chemokines attract neutrophils and monocytes, which squeeze out of the blood vessel wall and migrate to the infection site

5. newly arrived monocytes differentiate into macrophages. neutrophils and macrophages engulf pathogens and destroy them.

in response to pathogens, the initial release of ___, ___, and other mediators by mast cells and macrophages causes ___

histamine, prostaglandins; causes increased blood flow and exudation of plasma proteins, which contributes to redness, warmth, and swelling associated with inflammation

adaptive immune responses are carried out by

white blood cells called lymphocytes

what are the two broad classes of active immune responses?

antibody-mediated/humoral responses

cell-mediated responses

are T/B-lymphocytes the same as T/B cells?

yes

antibody/humoral responses are carried out by ___ lymphocytes, while cell-mediated responses are carried out by ___ lymphocytes

antibody - B

cell - T

describe the antibody-mediated immune response

B cells are activated to secrete antibodies, which are proteins called immunoglobulins.The antibodies circulate in the bloodstream and permeate the other body fluids, where they bind to the foreign antigen that stimulated their release.

antibodies are secreted forms of ___, secreted by ___.

immunoglobulins are present as cell surface-bound molecules on ___

antibodies are secreted forms of immunoglobulins, secreted by plasma B-cells.

immunoglobulins are present as cell surface-bound molecules on naive B-cells.

binding of antibody inactivates viruses and microbial toxins by

blocking their ability to bind to receptors on host cels.

___ marks invading pathogens for destruction by making it easier for phagocytic cells of the immune system to ingest them

antibody binding

describe the cell-mediated immune response

T cells recognize foreign antigens that are bound to MHC proteins on the surface of host cells such as dendritic cells, which are specialized for presenting antigen to T cells (therefore often referred to as antigen-presenting cells (APCs).

because MHC proteins carry fragments of pathogen proteins from inside a host cell to the cell surface, T cells can detect pathogens hiding inside a host cell and either kill the infected cell or stimulate phagocytes of B cells to help eliminate the pathogens.

T cells can only recognize antigens presented on antigen presenting cells in the context of

an MHC

T cells develop in the ___, B cells develop in the ___

T cells: thymus

B cells: bone marrow

list the 5 phases of adaptive immune response

antigen recognition, lymphocyte activation, antigen elimination, contraction and restoration of homeostasis, development of immunological memory

define the following: antigen, epitope, paratope

antigen - any foreign molecule that triggers an adaptive immune response

epitope (or antigenic determinant) - the small specific part of the antigen that the antibody molecules bind to

paratope - the corresponding site on the antibody that binds to an epitope

list the three ways antibody-bound antigens are processed to protect the host from infection

neutralization - inhibit the toxic effects or infectivity of pathogens by binding to them

opsonization - by coating the pathogens, they can enable accessory cells that recognize the Fc portions of arrays of antibodies to ingest and kill the pathogen

complement system activation

how are the polypeptide chains in antibodies, B cell receptors, and T cell receptors different?

B cell receptor - Y shaped immunoglobulin molecule with a transmembrane tail that anchors it in the plasma membrane. it has 2 identical antigen binding sites

antibody - differentiated from a B cell receptor, so very similar but without the transmembrane region

T cell receptor - one antigen binding site

antigens bind to the ___ regions

variable

differences in the ___ regions define 5 main isotopes/classes of immunoglobulin, which have different functions in the immune response

heavy-chain C

which immunoglobulins are monomers? What are the structures of the others?

monomers: IgG, IgD, IgE

IgA is a dimer

IgM is a pentamer

___ is always the first class of antibody to be secreted in an immune response. it is secreted as a ___ of immunoglobulin

IgM, pentamer

___, ___, and ___ are the main antibodies present in blood, lymph, and the fluid in connective tissues

IgM, IgA, and IgG

What is the most abundant antibody circulating in the blood and lymphatic system? It is produced in large amounts when the body is exposed a second time to the same antigen

IgG(γ)

these antibodies are produced in response to parasites and, in genetically susceptible individuals, to otherwise harmless environmental antigens (allergens).

IgE

5 steps of antibody-mediated immunity

1. Engulfment of bacterium

2. degradation of bacterium and release of antigens

3. Presentation of antigens on dendritic cell surface

4. Interaction of APC with lymphocyte

5. Activation of T cell

in antibody-mediated immunity, a bacterium is taken up by a ___ cell by ___

dendritic cell by phagocytosis

in antibody-mediated immunity, the bacterium is degraded within a ___. the released bacterial protein fragments act as ___

lysosome; antigens

in antibody-mediated immunity, antigens bind to ___ within the cell, resulting in an antigen-presenting cell (APC).

class II MHC proteins

in antibody-mediated immunity, the APC presents the antigen to ___ with a receptor that recognizes the antigen.

a CD4+ T cell

in antibody-mediated immunity, the ___ receptor binds directly to the ___ protein, resulting in the APC and T cell becoming linked.

CD4+ receptor binds to the class II MHC protein

in antibody-mediated immunity, the APC secretes ___, which ___

interleukins, which activate the T cell

the phenomenon whereby we develop long-lasting immunity to many common infectious diseases after our initial exposure to the pathogen, either through natural infection or vaccination.

immunological memory

how does the response to the same antigen change upon multiple exposures?

the secondary response is much quicker and more specific to a certain antigen the second time the immune system encounters it.

active immunity

production of antibodies in the body in response to exposure to a foreign antigen. immunological memory is produced by a primary immune response

passive immunity

acquisition of antibodies from another person, including antibodies passed from parent to child through the placenta or breast milk.

what are the uses of antibodies in research?

immunohistochemistry techniques: ELISA, immunoblotting

monoclonal antibody production - hybridoma technology

What are the steps of cell-mediated immunity?

1. Presentation of antigens on cell surface

2. activation of T cell

3. Production of cytotoxic T cells

4. Attack of infected cell by cytotoxic T cell

5. Destruction of infected cell

in cell-mediated immunity, viral proteins are degraded into fragments that act as antigens. The antigens are displayed on the cell surface bound to ___, making the cell an antigen presenting cell APC

class I MHC proteins

in cell-mediated immunity, the APC presents the antigen to a ___ cell with a receptor that recognizes the antigen. this cell receptor binds directly to the ___, resulting in ___

APC presents antigen to a CD8+ T cell

CD8 receptor binds directly to the class I MHC protein, resulting in the APC and T cell linking, which in addition to the secretion of interleukins by the T cell, activate the T cell.

in cell-mediated immunity, what happens after the CD8+ T cell is activated?

it proliferates to form a clone. Many of these cells differentiate into cytotoxic T cells, which fight infection. Some differentiate into memory cytotoxic T cells, which live long and respond rapidly if the same antigen is encountered later

cytotoxic cells are a type of ___

effector T cell

in cell-mediated immunity, what happens after the T cell receptor on a cytotoxic T cell recognizes the antigen bound to a class I MHC protein on the infected cell?

the T cell releases perforins

type 1 diabetes, lupus, rheumatoid arthritis, and multiple sclerosis are all ___

autoimmune diseases (increased immune response)

type 1 diabetes

an autoimmune reaction against the pancreatic beta cells producing insulin

lupus

produces antibodies against blood cells, platelets, mitochondria, and proteins associated with DNA

rheumatoid arthritis

attacks connective tissues in the joints, causing pain and inflammation

multiple sclerosis

attacks myelin sheaths of neurons

substances responsible for allergic reactions form a distinct class of antigens called allergens, which induce ___ to secrete an overabundance of ___. This results in ___

B cells, IgE antibodies. this results in the release of histamine, producing severe inflammation.

antihistamines counter the effects of what type of cell?

mast cells