immune system II - adaptive immune system

Question 1

what are the 5 distinct classes of antibodies?

Answer 1

IgM, IgA, IgD, IgG, igE

use MADGE to remember

Question 2

give the structure of antibodies

Answer 2

-fab regions contain specific antigen binding sites
-constant Fc tail region which contains binding sites for mediators of antibody-induces activities

Question 3

How does clonal expansion of B lymphocytes work?

Answer 3

1. the b cell clone specific to the antigen proliferates and differentiates into plasma cells and memory cells
2. plasma cells secrete antibodies that bind with free antigen
3. memory cells expand and the specific clone and are primed and ready for subsequent exposure to the same antigen

Question 4

what is the difference between primary and secondary immune response

Answer 4

primary
-delayed until formation of plasma cells
-decline of antibody levels

secondary
-rapid
-potent
-long term immunity
-action of memory cells
-specific immune response

Question 5

how do immunoglobins physically hinder the antigen with examples

Answer 5

-neutralisation e.g. IgG
-agglutination e.g. IgM
-antitoxin e.g. IgG, IgA

Question 6

what are the 5 actions of immunoglobins?

Answer 6

-physical hindrance of antigen
-enhance phagocytosis: opsonin marks target for destruction e.g. IgM and IgM
-helps in parasite destruction e.g. IgE binds helminth and eosinophils
-binds and activates mast cells/ basophils e.g. IgE for allergic reactions
-activates complement cascade and NK cells e.g. IgG, IgM

Question 7

What are the sequence of steps of antibody action?

Answer 7

1. neutralisation
2. agglutination
3. activation of complement system
4. opsonisation
5. stimulation of natural killer cells

Question 8

step 1: neutralisation?

Answer 8

binds bacterial toxins, prevents interaction with susceptible cells

Question 9

step 2: agglutination

Answer 9

1. antibodies bind to foreign cell antigen
2. formation of Ab-Ag complexes
3. complex too large to remain soluble
4. precipitation

Question 10

step 3: activation of complement system

Answer 10

1. Ab tail binds and activates C1
2. complement cascade
3. membrane-attack complex
4. destruction of specific invader

Question 11

step 4 - opsonisation

Answer 11

1. Abs act as opsonins
2. binds antigen on invader
3. Ab tail binds phagocyte receptor
4. phagocytosis of specific invader

Question 12

step 5 - activation of natural killer cells

Answer 12

NK cells receptors bind to Fc tail region of Abs. kills by lysis or inducing apoptosis

Question 13

Give the steps of cell mediated immunity

Answer 13

1. Pathogens invade body cells or are taken up by phagocytes
2. The phagocyte places antigens from the pathogen on its cell-surface membrane (antigen presentation)
3. Receptors on a specific helper T cell fit exactly onto these antigens
4. This attachment activates T cells to rapidly divide by mitosis and form a clone of genetically identical cells
5. The cloned T cells then:
   - develop into memory cells that enable a rapid response to future infections by the same pathogen
   - stimulate phagocytes to engulf pathogens by phagocytosis
   - stimulate B cells to divide and secrete their antibody
   - activate cytotoxic T cells

Question 14

what are the three types of helper T cells?

Answer 14

-Tc cells mediate cell death
-Th1 and Th2 modulate activity of immune cells, B and Tc cells
-Ts cells dampen down immune response

Question 15

what are the two functions of suppressor/ regulatory T cells?

Answer 15

-limits reaction of all other immune cells due to its negative feedback mechanism
-Th stimulate Ts which inhibits Th and other activated cells
this therefor prevents excessive immune response

Question 16

give examples of type 1 hypersensitivity and what it involves

Answer 16

-hives, hay fever, conjunctivitis
IgE antibody

Question 17

give examples of type II hypersensitivity and what it involves

Answer 17

-Rhesus Ab incompatibility, mismatch blood transfusion
IgM/ IgG

Question 18

give examples of type III hypersensitivity and what it involves

Answer 18

-Rheumatoid arthritis, glomerulonephritis
IgM/ IgG

Question 19

give examples of type IV hypersensitivity and what it involves

Answer 19

transplant rejection like graft-versus-host reactions and contact dermatitis
Th1 to Tc cells and macrophages

Question 20

for allergic conjunctivitis, what percent of the pop does it affect, what type of hypersensitivity is it and what are the two types and their allergens

Answer 20

-15-20%
-type I
-seasonal which has grass and tree pollen allergen
-perennial which has smoke, dust mites, animal fur all year etc as allergens

Question 21

what are the symptoms, signs and treatments for allergic conjunctivitis?

Answer 21

symptoms - red eye, itchy and watering, sneezing and nasal discharge
signs - pink conjunctiva, eyelid oedema, swollen conjunctiva, tearing, papillae under eyelid, water mucous discharge
treatment, nothing gets prescribed, topical anti histamine?

Question 22

what is vernal keratoconjunctivitis?

Answer 22

rare allergic disorder mostly affecting children, T cell mediated in type IV hypersensitivity, associated with a history of eczema and asthma

Question 23

for vernal keratoconjunctivitis, what are the symptoms, signs and treatments

Answer 23

symptoms: itchy, burning, watery, blurred vision, corneal pain
signs, red conjunctiva, giant papillae, swelling, limbal inflammation, trantas dots, cornea has neovascularisation, and epithelial erosion, discharge of stringy mucous
treatment, referral ocular lubricants, topical anti inflammatory , systemic anti histamines or topical mast cell stabilisers

Question 24

look up atopic keratoconjunctivitis

Answer 24

ok