UWEC BIOLOGY 221 FINAL (Unit 5)

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What are the two main branches of the immune system?  Describe the characteristics of each.

Innate Imunity:

Adaptive Immunity:

IgA: Functions

Defends against infections in respiratory/digestive tract

IgD: Functions?

Initiate immune response; bind to antigens, signal to B cells

IgE

Allergic reactions: triggers release of histamines

IgG: Functions?

Neutralize bacteria/viruses; activate complement system

IgM: Functions?

First antibody product; activates complement system

Which innate immunity components function as first line defenses?

Skin, mouth—>anus, eye, urogenital tract, alimentary tract, respiratory tract

How do intact skin and mucous membrane function to prevent the entry of microbes into sterile body sites?

Their structure prevents microbes from entering

Describe how the muco-ciliary escalator functions.  What body system does this protect?  What can cause the muco-ciliary escalator to stop functioning?

Muco-ciliary escalator protects the respiratory tract

Actions like smoking can cause the muco-ciliary escalator to stop functioning

Describe the flushing mechanisms that are part of the innate defenses.

Coughing, sneezing, crying, urination, defecation

Lysozyme: what microbial feature is the target for this enzyme?

Breaks the peptidoglycan (Lysis)

 Lactoferrin: how does this inhibit microbial growth?

Siderophore, binds iron.

Iron is a cofactor and is required for enzymes, lactoferrin take away iron from enzymes

Fatty acids: Functions?

Have antimicrobial properties, inhibits

Acidic environments: how does this inhibit growth?  What are examples of acidic environments on the human body?

pH is close to 0, kills microorganisms.

Tummy

What is normal flora and how does this function in innate immunity?

Normal flora are microbes that normal inhabit body surfaces

It is a barrier to the attachment of potential pathogens. Takes up all the space that pathogens/viruses want to attach.

What are stem cells and where are they formed?  What cells can be formed from stem cells?

Stem cells have the potential to become any type of blood cell

They are formed in bone marrow

a.      What is the name of the process by which blood cells are formed?

Hematopoeisis

Which leukocytes are classified as granulocytes?

Grainy

Ex. Eosinophils, basophils, neutrophils

Which leukocytes are classified as agranulocytes?

Not grainy

Ex. Monocytes, Lymphocytes (T cells and B cells)

What function do phagocytes perform in the immune system?  What specific cells function as phagocytes?

ENGULF AND DESTROY

Neutrophils, monocytes, macrophages, dendritic cells

In which branch of the immune system do lymphocytes function?

Lymphocytes function in the adaptive immune system, where they play a crucial role in recognizing specific antigens and generating tailored immune responses.

Describe the function of each type of lymphocyte?

NATTY KILLERSSSS RAHHHHH. Identify abnormal cells and kill it!!!

Chemokines: Function?

Induce chemotaxis

Colony stimulating factors: Function?

Differentiation

Interferons

Antiviral, induce fever, inflammation

Interleukins

Produced by leukocytes

Tumor necrosis factors

Inflammation, apoptosis

What are pattern recognition receptors?  What are PAMPS?

Pattern recognition receptors are PAMPs and DAMPs

PAMPs are Pathogen-Associated Molecular Patterns found on pathogens that trigger an immune response in the host

Ex. Peptidoglycan (Only found in bacteria)

Describe how toll-like, NOD-like, and RIG-like receptors function in innate immunity.

Toll like: Detects pathogens outside the cell

NOD-like: Detects pathogens inside the cell

RIG-like: Detects pathogens inside the cell, specifically viral PAMPs and DAMPs

Describe the three ways in which the complement system can be activated.

Classical pathway, Lectin Pathway, Alternative Pathway

What are the three outcomes of activating complement?

Inflammation, Lysis of foreign cells, opsonization

What complement components help activate inflammation?

C3 and Cea

What complement components form the membrane attack complex?  How does the membrane attack complex kill microbes?

C5b, C6;C7;C8;C9

Creates pores in the cell membrane (disrupts cell integrity)—>Lysis

What is opsonization?  What complement components can function as opsonins?

Opsonization is when C3b binds to microbial cells, functioning as an opsonin.

What is the first step in phagocytosis?  How can opsonization enhance the efficiency of this step?

First step of phagocytosis is attachment

Opsonization enhances the efficiency of this step because phagocytes have C3b receptors that can attach to the coat of C3b

What is the difference between a phagosome and a phagolysosome?  In which vesicle does killing of the engulfed microbe take place?  What do phagocytes use to kill engulfed microbes?  Where are the molecules used to kill microbes stored within the phagocyte?

A phagosome is a membrane bound vesicle. A phagolysosome phagosome and lysosome.

Killing of the engulfed microbe takes place in the phagolysosome.

Phagocytes use the phagolysosome to kill the engulfed microbes

The molecules used to kill microbes stores within the phagocyte is stored within  the phagocyte

What happens to the microbial debris once the microbe has been killed?

The microbial debris is eliminated by exocytosis

What are the signs that an inflammatory response is taking place?  What causes these signs to occur?

Swelling, redness, heat, pain

Microbial products (LPS, flagellin, bacterial DNA) stimulate toll-like receptors to release pro-inflammatory cytokines; Microbial surfaces activate complement; Tissue damage: Coagulation cascade, release of pro-inflammatory cytokines

How can inflammation be triggered?  Describe the specific mechanisms.

Release of vasoactive cytokines: Blood vessels: Initially constrict —> vasodilation —> accumulation of fluids in tissues

Attraction of leukocytes: Chemokines, other chemoattractants; Neutrophils —> lymphocytes —> macrophages. Leave circulation using diapedesis

What are vasoactive cytokines and what effect do they have?  Be familiar with the examples of vasoactive cytokines discussed in class.

Blood cells: Constrict —> Vasodilation —> accumulate fluids in tissues (blood)

How does the function of vasoactive cytokines contribute to the development of the signs of inflammation?

Site of cut feels warm, site of cut hurts,

What beneficial immune system components enter the tissues due to vasodilation?

White blood cells, plasma, complement proteins, siderophores,

How are leukocytes attracted to a specific area during inflammation?  What leukocytes are the first to arrive?  Which leukocytes arrive next?  Which leukocytes arrive last?  How do these groups of leukocytes help to remove microbes in the area?  What is the process by which leukocytes leave circulation and enter the tissues?

Leukocytes are attracted to a specific area during inflammation because of chemokines

Neutrophils are first to arrive (phagocyte)

Next leukocyte is lymphocytes (T cells and B cells)

Last leukocyte is macrophages (white blood cell)

Neutrophils are phagocytes that engulf and kill. Lymphocytes (T cells and B cells) are part of adaptive immunity, so they engulf and kill anything the neutrophils don’t eat up. Macrophages clean up their mess and take out the garbage.

Leukocytes leave circulation by diapedesis

What are the outcomes of inflammation?  What cells predominate during each outcome?  How does the location of an inflammatory response affect the outcome?  What is septic shock?  What causes septic shock?  What happens during septic shock and why does this happen?

Acute inflammation: Neutrophils predominate, promote clearance of damaged cells and healing damaged tissues and cells

Chronic inflammation: Macrophages predominate, damage

The location of an inflammatory response affects the outcome

What are interferons?  Why are interferons considered a sensing system?  What molecular pattern is being detected and by what receptors?

Interferons are PAMPs

Interferons are considered a sensing system because they detect viruses

The molecular pattern being detected are RIG-like receptors

Describe the process by which interferons can stop the viral replication process.

Virus attaches to cell —> Cirus infects cell —> Virus replicates —> leaves behind a piece(ds RNA)(PAMP) —> PAMP gets bound by RIG-like receptors in cytoplasm —> Triggers signaling pathway —> Infected cell produces and releases interferon —> Interferon binds to neighboring cells —> Triggers signaling pathway à Neighbor cell prepares anti-viral proteins

What is the difference between an exogenous pyrogen and an endogenous pyrogen?  Be able to provide examples of each.

Exogenous pyrogen is a pyrogen found outside the cell

Ex: Microbial products (LPS, super antigens)

Endogenous pyrogen is a pyrogen found inside the cell

Ex: Mady by body (IL-1, IL-6)

What benefits are associated with a fever response?

Inhibits growth of some pathogens

Speeds up immune response

What is a primary immune response?  How long does it take to develop?

Primary immune response is an adaptive response on first exposure (First time encountering an antigen)

Take a week<= to develop

What is a secondary immune response?  How long does it take to develop?

A secondary immune response is the exposure to the antigen after the first exposure

Develops fast!

What cells mediate humoral immunity?  What type of antigens induce a humoral immune response?  What are the products of a humoral immune response?

B cells mediate humoral immunity

Extracellular antigens/Exogenous antigens induce a humoral immune response

Humoral immune response produces antibodies and memory B cells

What cells mediate cellular immunity?  To what type of antigens is cellular immunity directed?  What are the products of cellular immunity?

T cells mediate cellular immunity

Intracellular antigens are directed to cellular immunity

Cellular immunity produces cytotoxic T cells, activates macrophages, and memory T cells

 

  What role do helper T cells play in humoral and cell mediated immunity?

T cells activate B cells in humoral immunity

T cells activate macrophages that have an engulfed antigen and stimulate effector T-cytotoxic cells that bind antigen

What types of molecules make the best antigens?  The worst?

The best antigens are made of proteins or polysaccharides

The worst antigens are made of lipids and nucleic acids

What is an epitope (antigenic determinant)?  Can an antigen have more than one epitope?

An epitope is a part of a molecule that stimulates response (what is recognized)

Antigens can have more than one!!

How many heavy chains are found in an antibody monomer?  How are they connected? 

Two heavy chains are found in an antibody monomer.

Connected by disulfide bonds

What is the difference between the variable region and constant region of a heavy or light chain?

The variable region is responsible for antigen recognition and binding, while the constant region determines the antibody's isotype and mediates its effector functions. 

What part of an antibody molecule determines the class of an antibody?

Heavy chains determine the class of an antibody

To what part of an antibody molecule does an epitope bind?  How many epitope binding sites are present on an antibody monomer?  How many different epitopes can a single antibody monomer bind?

An epitope binds to the light chain and heavy chain cleft region of an antibody

An antibody monomer can have two epitope binding sites

Any type of epitope!

What is opsonization?  Which antibodies function as opsonins?

Opsonization is a process where opsonins coat foreign molecules so they can be better recognized

Which classes of antibodies can activate complement?

IgM and IgG can activate the complement through the classical pathway.

 

What is antibody dependent cellular cytotoxicity (ADCC)?  What classes of antibody participate in ADCC?  What type of leukocyte participates in ADCC?  What is its role in ADCC?

Antibody dependent cellular cytotoxicity is where antibodies coat a microbial cell and is now better recognized by natural killer cells.

IgG antibodies participate in ADCC

Neutrophils (natural killers) participate in ADCC

NK’s kill the microbial cell

How do antibodies neutralize pathogens?

Marking them by coating them to be recognized

How do antibodies immobilize pathogens?  How do antibodies lead to agglutination/precipitation?

Antibodies bind to the flagella of the pathogens

Antibody molecules have two epitope binding sites —>Antigens clump up —> Immune system can easily detect them now

What cell surface antigen receptors are used to bind antigens?  What type of antigens are bound?

B cells utilize B-cell receptors (BCRs) to bind antigens, while T cells employ T-cell receptors (TCRs)

How many different epitopes can a single B cell recognize and bind?

One

How is the bound antigen internalized by the B cell?

The bound antigen is internalized by the B cell by using IgM/IgD in receptor mediated endocytosis

What happens to the antigen once it is internalized by the B cell?

The antigen is degraded and then presented

What specific molecule is used to present the antigen on the surface of B cells?

Major histocompatibility complex 2 is used to present the antigen on the surface of B cells.

What type of leukocyte surveys antigens presented by MHC II?  What happens when this leukocyte activates the B cell presenting the foreign antigen?

Helper T cells (Cd4)

Clonal expansion —> B cells become plasma cells/memory B cells

Why do cells present antigen?  What cells survey presented antigen

Cells present antigens as a flare

What is an endogenous antigen?  What types of cells can present endogenous antigen?  What molecule is used to present endogenous antigen on the cell surface?  What types of molecules can be presented?  What types of leukocyte surveys antigen presented by MHC I

ndogenous antigens are antigens produced within the cell, such as viral proteins or tumor-specific antigens. All nucleated cells can present endogenous antigens. These antigens are presented on the cell surface using Major Histocompatibility Complex I (MHC I) molecules. Molecules presented include peptides derived from intracellular proteins. Cytotoxic T cells (CD8+) survey antigen presented by MHC I.

 

  What is an exogenous antigen?  What types of cells can present exogenous antigen?  What molecule is used to present exogenous antigen on the cell surface?  What types of molecules can be presented?  What types of leukocytes surveys antigen presented by MHC II?

Exogenous antigens are antigens from outside the cell, such as bacteria, viruses, or toxins. Antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells can present exogenous antigens. These antigens are presented on the cell surface using Major Histocompatibility Complex II (MHC II) molecules. Molecules presented include peptides derived from the engulfed extracellular pathogens. Helper T cells (CD4+) survey antigens presented by MHC II.

Describe the process by which a humoral immune response is activated.  Include in your description the type of antigen recognized, how the antigen is processed and presented, the specific T cell that will survey the presented antigen, the specific mechanism by which the B cell becomes activated, and what happens to the B cell once it is activated that leads to the production of antibody and memory B cells.

The humoral immune response is initiated when B cells recognize extracellular antigens. The antigen is then internalized, processed, and presented on the B cell surface via MHC II molecules. Helper T cells (CD4+) recognize these MHC II-antigen complexes and activate the B cell through co-stimulatory signals. Activated B cells undergo clonal expansion, differentiating into plasma cells (which produce antibodies) and memory B cells.

 

Describe the process by which a cell mediated immune response is activated.  Include in your description the type of antigen recognized, how the antigen is processed and presented, the specific T cell that will survey the presented antigen, the specific mechanism by which the T cell becomes activated, and what happens to the T cell once it is activated that leads to the destruction of the antigen presenting cell and the production of memory T cells.

Intracellular antigens are processed and presented by infected cells via MHC class I molecules. Cytotoxic T cells (CD8+) recognize these MHC I-antigen complexes. T cell activation requires co-stimulatory signals. Once activated, cytotoxic T cells kill infected cells while memory T cells are generated, thus establishing the cell-mediated immune response.