BIOL10002 Lecture Notes - Pronucleus, Umbilical Cord, Epididymis

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graycamel28

2 Jul 2018

School

University of Melbourne

Department

Biology

Course

BIOL10002

Professor

Mary

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Week 10

Lecture 26

The Immune System part 2

Adaptive immunity

 Antibodies

- B cell receptors are membrane bound antibodies

 T-cell receptors (T-cells)

 MHC (Major histocompatibility complex)

- Determines self and not self

 Cytokines

- Can be peptides, proteins or glycoproteins

- Secreted by T helper cells

- Activate or inhibit B cells

- Macrophages, T-cells

 antigens and antigenic determinants (molecules, or molecules on the outside of pathogens)

- interacts with specific receptors on T-cells and B-cells

- immunogens = something that causes and immune response

- not all antigens are immunogenic, but all immunogens are antigens

- antigenic determines = epitopes (specific region on an antigen recognises by a specific antibody or T-cell receptor)

Key features

1. Specificity

2. Distinguishes self from non-self

3. Diversity

4. Immunological memory

Specificity

 antibodies and T cell receptors bind to specific antigens

Humoral = fluid

- antibodies secreted by plasma cells to target antigens in body fluids

- antibodies: have variable regions (made up of some light + some heavy chain) and constant regions (determines

class of antibodies – there are 5), light (outside) and heavy (inside) regions, held together by di-sulphide bonds

B-cells

 B memory cells – (effector cells) remembers (long acting), can also secrete antibodies and endocytose pathogens

 B plasma cells – secrete antibodies (short acting)

Cellular = cells

- T cells attack body cells altered by infection of mutation

T cells

 T helper cells – assist humoral and cellular, respond to cytokines that direct the action of other cells

 T cytotoxic cells – respond by releasing perforins that poke holes in and lyse the infected cells

- T cell receptors have an alpha chain and a beta chain

MHC

 membrane bound glycoproteins that direct recognition of self from non-self

1. Macrophage takes up antigen and breaks it down into fragments

2. A class II MHC molecule binds antigen fragment and carries it to the membrane

3. The MHC molecule displays the antigen on the membrane to present it to the TH cells

Note: MHC I is on infected cells, MHC II is on healthy self cells

Antibody binding promotes phagocytosis

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Diversity

Naïve cells becoming bad or good:

 There are millions of possible specific antibodies and T-cell receptors as a result of many possible DNA

combinations

 The immune system can respond to a wide variety of pathogens

- e.g. antibody heavy chain gene recombination

The line of the gene gets transcribed and then chopped up into many different ways to get multiple possible

combinations of amino acid order, the ones of use are kept but the ones that aren’t helpful are deleted (clonal

deletion). If this doesn’t work = autoimmune diseases

Immunological Memory

 When a pathogen is recognised for a second time -

- immunisation gives exposure to disease causing pathogen = natural immunity via memory B and T cells

- vaccination (artificial) introduces an attenuated pathogen (does not cause disease) = memory B and T cells

- Clonal selection: A B cell is selected for proliferation to form a clone = memory cells

- Clonal deletion: when immature B and T cells show the potential to harm the body’s own antigens, and undergo

apoptosis

- failure of clonal deletion results in autoimmune diseases, such as type 1 diabetes and rheumatoid arthritis

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Document Summary

B cell receptors are membrane bound antibodies. Antigens and antigenic determinants (molecules, or molecules on the outside of pathogens) Interacts with specific receptors on t-cells and b-cells. Immunogens = something that causes and immune response. Not all antigens are immunogenic, but all immunogens are antigens. Antigenic determines = epitopes (specific region on an antigen recognises by a specific antibody or t-cell receptor) Key features: specificity, distinguishes self from non-self, diversity, immunological memory. Antibodies and t cell receptors bind to specific antigens. Antibodies secreted by plasma cells to target antigens in body fluids. Antibodies: have variable regions (made up of some light + some heavy chain) and constant regions (determines class of antibodies there are 5), light (outside) and heavy (inside) regions, held together by di-sulphide bonds. B memory cells (effector cells) remembers (long acting), can also secrete antibodies and endocytose pathogens. B plasma cells secrete antibodies (short acting) T cells attack body cells altered by infection of mutation.

Related Questions

1.How do some pathogens prevent complement activation or avoid the effects of activated complement?

A. some pathogens hijack the host's regulatory membrane proteins that inactivate C3b, preventing the triggering of the alternative activation pathway AND some pathogens produce C5a peptidase that causes destruction of phagoctyes recruited to the area of infection

B. some pathogens produce C5a peptidase that causes destruction of phagoctyes recruited to the area of infection

C. some pathogens produce C5a peptidase that destroys complement C5a, a chemoattractant that recruits phagocytes to the area of infection

D. Some pathogen hijack the host's regultory membrane proteins that inactivate C3b, preventing the triggering of the alternative activation pathway AND some pathogens produce C5a peptidase that destroys complement C5a, a chemoattractant that recruits phagocytes to the area of infection.

2. One of the most important jobs of dendritic cells is

A. production of complement proteins

B. activation of T cells by breakdown of whole antigens and presentation of antigenic epitopes on MHC molecules

C. stimulation of cytokine production by neutrophils

D. activation of B cells by combining epitopes and presentation of whole antigens on MHC molecules

E. production of IgD

3. Normal Microbiota

A. play no role in affecting pathogen growth

B. are the organisms that typically reside on and in your body

C. enhance infection by pathogens

D. are the organisms that typically reside on and in your body AND protect aganist infection by pathogens

E. protect against infection by pathogens.

4. why is the process of gene rearrangement used in creating antibodies and T-cell receptors (TCRs) so important?

A. the given choices are all reasons that generearrangement is critical in adaptive immunity

B. This is how our systems produce memory of previous exposures, a key trait in adaptive immune responses

C. without it, we would need a single gene for every antibody and TCR required to mount all the possible responses needed during our lives

D. interactions with antigens stimulate cells to initate these processes, building the best and strongest response possible to that antigen

E. this is the same DNA altering process that leads to cancer. Understanding it leads to better treatments for cancer.

1. during inflamation fluid will passively diffuse out of blod vessels into the nearby infected tissue. This implies all of the following EXCEPT

a.the osmolarity of the fluid surrounding infected tissues is higher than the plasma b the surrounding tissue will swell with excessive fluids c near by cappilaries have become more pearmeable d B-lymphocyte will differeniate to become plasma cell

2. which of the following best describe the qualities of most antigens?

a macromolecules that are foreign to the host b atomic elements that are not normally present in the human body c macromolecules tah tare produced by the host organism d atomic elements that are harmful or toxic

3. an adbantages to adaptive immunity is

a its memory cell that provide quicker larger and more efficient immune response upon second exposure to an antigen b its need for several cells to be activated over several days on first exposure c the ability for its individul cells to respond to many differnt pathogens d the use of antibodies that cause cells lysis and kill invading cells

4, an advantages of innate immunity is

a its a barrier taht prevent pathogens from entering into the body b the specifcity of its individual cell which specialize in the removal on one type of antigen c the numerous step in the activation of its cell that can prevent autoimmune disease d the use of the antibodies to cause cell lysis and kill invading cell

5. B- lymphocytes are categorized as part of the adaptive branch of the immune sys for all of the following reason but one Which of the following is NOT one part of reason B lyphocytes are considered part of the adaptive immunity?

a they produce memory cell when activated b their receptors will bind to only one antigen c they require costimulation from an activated T helper cell d thet are a first line of defense that can begin killing

6. Over lap in the innate and adaptive immune sys is seen in all of the following examples but one Which of the following examples does NOT illustrate the over lap of innate and adaptive immune resposes ??? a dendritic cell presenting antigen on their MHC II proteins to T helper cells b macrophage becoming activated macrophages in response to cytokines realesed by T helper cells c natural killer cell causing of an abnoraml host cell lacking MHC proteins d Plasma cell that produce large amounts of IgE that will ultimetly allow mast cell to relase histamine

7. Which of the following examples below describe an autoimmune disease? a infection and death of T helper cells bya virus resulting in a loss of adaptive immunity b realse of bacterial endotoxins that block acetylcholine realse result is muscle paralysis c antibody binding to acetylcholine receptors of hte motor end palte resulting in muscle weakness.d uncontrolled cell division resulting in cell surface abnormalities recognized by natural killer cell.

8. Which of he following does NOT describe actions of interferon IFN? a virally infected cell can release interferon which attracts natural killer cell to attack and kill the IFN secreting cell b IFN binds to normal uninfected cell stimulating the activation of genes that produce anti viral proteins c IFN will attract macrophages to the secreting cell to be removed bt phagocytosis d IFN can penetrate the virla capsid and destroy the virus

HI HELP PLEASE I NEED ANSWERS TO ALL QUESTIONS PLEASE THANKS

1. during inflamation fluid will passively diffuse out of blod vessels into the nearby infected tissue. This implies all of the following EXCEPT

2. which of the following best describe the qualities of most antigens?

3. an adbantages to adaptive immunity is

4, an advantages of innate immunity is

6. Over lap in the innate and adaptive immune sys is seen in all of the following examples but one Which of the following examples does NOT illustrate the over lap of innate and adaptive immune resposes ??? adendritic cell presenting antigen on their MHC II proteins to T helper cells b macrophage becoming activated macrophages in response to cytokines realesed by T helper cells c natural killer cell causing of an abnoraml host cell lacking MHC proteins d Plasma cell that produce large amounts of IgE that will ultimetly allow mast cell to relase histamine

BIOL10002 Lecture Notes - Pronucleus, Umbilical Cord, Epididymis

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