Antibodies

Question 1

Review T cell Development

1. Where are T cells produced?
2. describe the steps in their maturation (locations mostly)
3. what are the 1’ and 2’ lymph organs?

Answer 1

1. T cells are made in the RBM
2. RBM –> circulation –> thymus gland secretes chemokines to cause chemotaxis –> thymus –> Spleen & LNs
3. Thymus gland is 1’ lymph organ
   - Spleen & LN are 2’ lymph organs

Question 2

What are the thymic factors and what is their role?

bonus if you can then describe whole path to CD4 and CD8

Answer 2

thymosin, thymopoetin, thymic –> stimulate T cell DNA to make Rag 1 & 2

Bonus:

Rag1 & 2 shuffle DNA to make proteins –> insert proteins on surface of T cell –> called TCRs (t cell receptors)

Rag 1 & 2 activate cluster differention proteins (CD4 & CD8)

Question 3

What two things do RAG 1 & 2 do (related to T cell development)?

Answer 3

1) Rag1 & 2 shuffle DNA to make proteins –> insert proteins on surface of T cell –> called TCRs (t cell receptors)
2) Rag 1 & 2 activate cluster differention proteins (CD4 & CD8)

Question 4

What cells are MHC-1 and MHC-2 on/associated with?

Answer 4

MHC-1 = CD8 cells

MHC-2 = CD4 cells

Question 5

What cells perform positive/negative selection of MHC/T cell complexes?

Answer 5

-thymic cells

Question 6

What is positive T cell selection?

What is the next step for these cells after this positive selection?

Answer 6

Positive selection: when MHC is bonded correctly with its corresponding T cell

2) Next, TCRs are tested to make sure it does not bind itself –> this is negative selection!!

Question 7

What happens to T cells that are not bonded correctly with MHC/CD of the cells or if a TCR has bound itself?

Answer 7

thymic cells release FAS –>triggers apoptosis

Question 8

What happens if a CD4 is interacting with it’s correct MHC-2?

Answer 8

• This cell becomes a T helper cell (CD4+)
• Then CD8 cells are downregulated

Question 9

What happens if a CD8 is interacting with it’s correct MHC-I?

Answer 9

It becomes a CD8+ cytotoxic T cell

Question 10

1) What cells can become T reg cells?
2) what is T reg cells’ purpose and where are they located?

Answer 10

1) CD4+ & CD8+ can both become T regs
2) Tregs are for controlling CD4+ & CD8+ cells
- Tregs located in thymic corpuscles
- Tregs put CD4 & CD8 into deep LN cortex & white pulp of spleen blood vessels

Question 11

1) IgG structure & function (mechanism)

Answer 11

1) IgG is a monomer made in plasma cells
- it is most abundant in 2’ immune response

Mech: IgG binds Ag triggers 3 things?

–> starts complement system

–>forms MAC (opsonizatino)

–> leads to increase in C3 & C5 to increase inflammation?

IgG binds free Ag –>phagocytosis & opsonization = precipitation

Question 12

1) What is special about IgG’s action on viruses?
2) how is IgG related to passive immunity?
3) What HSR is IgG involved in?

Answer 12

1) IgG binds to every Ag on the virus –> blocks its entry into cells

This process is called Neutralization

2) IgG can cross the placenta!! gives fetus passive immunity @ birth
3) Type 2 & 3 HSR

Question 13

1) IgA structure & location
2) how is it related to passive immunity?

Answer 13

1) plasma cells secrete IgA as a dimer into skin & saliva & GI mucosa
2) IgA is passed through breast milk!

Question 14

1) IgM structure & function (mechanism)
2) what is our controversial notes say about HSR involving IgM

Answer 14

1) plasma cell secretes as a pentamer (j protein connector) or as a monomer

Function: 1’ immune response, if high it usually means it is an active infxn

IgM –> activates complement –> MAC & opsonization

2) Our notes say IgM is 1’ actor in mismatched ABO group blood transfusions [this may be true, but IgG is also involved] and thus could be labeled as Type II. Also can have type I [anaphylaxis] HSR to blood transfusion but it is actually reaction to plasma proteins in the blood transfusion

Question 15

1) IgE structure, location & function (mechanism)
2) What HSR is IgE involved in?
3) besides allergens, what is IgE created to react against?

Answer 15

1) plasma cells secrete IgE as monomers into resp tract mucosa, urogenital mucosa, lamina propria and lymph tissue

For allergens:

IgE binds mast cell –> releases H/L/P –>vasodilation & leaky cells (causes pulm edema & edema in general) & bronchoconstriction –>all signs of anaphylaxis

2) Type 1 HSR!!!
3) parasites!! and IgE is used to attract esoinophils –> eos make major B protein –> kills parasite

Question 16

How much IgE is in the blood?

Answer 16

trace amounts

Question 17

1) IgD structure & function (mechanism)

Answer 17

1) igD secreted by plasma cells as monomers –>then these fuse with plasma cell membrane & becomes B cell receptor

Otherwise we don’t really know much about its function

Question 18

Somatic Hypermutation, what is it?

Answer 18

SHM is the switching between plasma cell secretion of Ig’s

ex) IgM to IgG

Question 19

Give examples of passive immunity, both natural and artificial!

Answer 19

Natural = IgG passed over placenta and IgA passed through milk to baby

Artificial = antivenom (injection that has antibodies against the venom and blocks it from spreading)

Question 20

Give examples of active immunity, both natural and artificial!

Answer 20

Natural = self infected & antibodies produced against antigens

Artificial = vaccination!!

Question 21

Describe antibody structure! (Just see picture for answers)

Answer 21

recombination is important