immune system II - adaptive immune system Flashcards
what are the 5 distinct classes of antibodies?
IgM, IgA, IgD, IgG, igE
use MADGE to remember
give the structure of antibodies
-fab regions contain specific antigen binding sites
-constant Fc tail region which contains binding sites for mediators of antibody-induces activities
How does clonal expansion of B lymphocytes work?
- the b cell clone specific to the antigen proliferates and differentiates into plasma cells and memory cells
- plasma cells secrete antibodies that bind with free antigen
- memory cells expand and the specific clone and are primed and ready for subsequent exposure to the same antigen
what is the difference between primary and secondary immune response
primary
-delayed until formation of plasma cells
-decline of antibody levels
secondary
-rapid
-potent
-long term immunity
-action of memory cells
-specific immune response
how do immunoglobins physically hinder the antigen with examples
-neutralisation e.g. IgG
-agglutination e.g. IgM
-antitoxin e.g. IgG, IgA
what are the 5 actions of immunoglobins?
-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
What are the sequence of steps of antibody action?
- neutralisation
- agglutination
- activation of complement system
- opsonisation
- stimulation of natural killer cells
step 1: neutralisation?
binds bacterial toxins, prevents interaction with susceptible cells
step 2: agglutination
- antibodies bind to foreign cell antigen
- formation of Ab-Ag complexes
- complex too large to remain soluble
- precipitation
step 3: activation of complement system
- Ab tail binds and activates C1
- complement cascade
- membrane-attack complex
- destruction of specific invader
step 4 - opsonisation
- Abs act as opsonins
- binds antigen on invader
- Ab tail binds phagocyte receptor
- phagocytosis of specific invader
step 5 - activation of natural killer cells
NK cells receptors bind to Fc tail region of Abs. kills by lysis or inducing apoptosis
Give the steps of cell mediated immunity
- Pathogens invade body cells or are taken up by phagocytes
- The phagocyte places antigens from the pathogen on its cell-surface membrane (antigen presentation)
- Receptors on a specific helper T cell fit exactly onto these antigens
- This attachment activates T cells to rapidly divide by mitosis and form a clone of genetically identical cells
- 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
what are the three types of helper T cells?
-Tc cells mediate cell death
-Th1 and Th2 modulate activity of immune cells, B and Tc cells
-Ts cells dampen down immune response
what are the two functions of suppressor/ regulatory T cells?
-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
give examples of type 1 hypersensitivity and what it involves
-hives, hay fever, conjunctivitis
IgE antibody
give examples of type II hypersensitivity and what it involves
-Rhesus Ab incompatibility, mismatch blood transfusion
IgM/ IgG
give examples of type III hypersensitivity and what it involves
-Rheumatoid arthritis, glomerulonephritis
IgM/ IgG
give examples of type IV hypersensitivity and what it involves
transplant rejection like graft-versus-host reactions and contact dermatitis
Th1 to Tc cells and macrophages
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
-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
what are the symptoms, signs and treatments for allergic conjunctivitis?
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?
what is vernal keratoconjunctivitis?
rare allergic disorder mostly affecting children, T cell mediated in type IV hypersensitivity, associated with a history of eczema and asthma
for vernal keratoconjunctivitis, what are the symptoms, signs and treatments
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
look up atopic keratoconjunctivitis
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