Lecture 21 - cell mediated immunity Flashcards
complement cascade
-do more on this!
IGM
- largest molecule
- mostly blood and lymphatics
- First in primary antibody response
- very effective agglutinator
- good activated of compliment pathway
- important defence against blood borne spread of infections such as bacteria
IGG
smaller
- main antibody in pool
- diffuses into extravascular spaces
- potent antitoxin antibody
- effective barrier against viral infections
- actively transported across placenta
- good complement activaor
- strongly bound to pahgocytic cells to enhance pahgocytosis
IGA
main role is protection of external body surfaces
surface protection of gut, resp and genitourinary tracts
IGD
- very small amounts in blood and body fluids
- found on surface of antigen sensitive naive B cells
- Receptor for antigen binding to activate naive B cells
IGE
- generally not much in blood
- bind strongly to mast cells - this causes the symptoms , granules released
- people that make more of this have allergic reactions and asthma
- important in parastiic infections and allergins
Antisera
immunise an animal with an antigen and purify serum from animal and then get antibodies specific from things
- mainly made in large animals and can make lots of antibodies to fight against antigens
- however these were mainly polyclonal antibodies - making a range of different antibodies and not alot of one specific type
- want monoclonal antibody
Lymphadenopathy (enlarged lymph nodes) and splenomealy
lymphocytosis
-what can be done for treatment involved with monoclonal antibodies
- can use chemotherapy which contains a monoclonal antibody directed against B cell surface antigens - pure antibody prepared in lab
- able to be injected and can bind to these and kill them
lymphocytosis - increase in no. of lymphocytes in the blood
Skin graft rejection
-what happens with primary graft vs secondary graft
First graph - taken from a different person, has been sewn into place
- if it is not compatable with recepipietn then will look like big blood dot thats dead- dies due to immune response due to T cell mediated recognising the antigen and responding
- Second graft - from same donor to same recipient where graft doesnt vascularise very wel, and is rejected quickly - will be more immediate as memory cells will be there and will be mostly antibody mediated
Cytotoxic T cell action
-3 ways of action
All of these use recognition of target and CD8
-recognition causes the release of granules
- Perforin and enzymes, these are similar to late components of complement cascade to go onto punch holes in membranes
- Hydrolytic enzymes (granzymes) - get throguh the holes and start to digest the cell they are attatched to
- Cytokines released that induce apoptosis in some of the target cells
Lymphocyte ontogeny (how lymphocytes are made)
-where do b and t cells originate, mature, and migrate to
Bone marrow and thymus - primary lymphoid organs - make B and T cells
T cells differentiate in thymus, then travel to secondary lymphoid organs
B cells leave bone marrow mature, and also go to secondary lymphoid organs
B cell ontogeny
stem cells - triggered by various molecules, go to B cell lineage
- pre b cells
- immature b cell - surface IgM
- mature b cell - surfaec igM and igD
immunoglobulin genes
- have 2 sets of genes that code for antibodies
- one for heavy chain, 2 for light chains
- V, D, J exons, C exons
- get veriable region of heavy chain - in bone marrow - there is random reassortment of heavey chain (of V, D, J)
- get many different combination of V,D,J that code for the variable region of the heavy chain
- then these become transcribed and translated
- heavey and light chain together become the surface ig on B cells
- cna regonise loads of different antigens
Class switching
- any antibody can switch from IGM, to make IGG but have same variable regions
- heavy chain is variable, and the light chain is not variable but can change
- could transcribe all the rna for the Cu to Ca region
- or could chop out some of the exons and end without some of the regions
- the T cells control the switching
- but have same antigen binding site
V region stays constant, C region changes
