MTII Flashcards
(184 cards)
How did Metchnikoff propose cell-mediated immunity? What was the reception to the theory
He published his observations of starfish larvae phagocytes surrounding a thorn.
Her opposed that the body was defended against invasion by such phagocytes in a process analogous to inflammation
- his proposal was not well received
Who proposed cell mediated immunity and when
Ilya metchnikoff in 1882
Why was Metchnikoff theory of cell mediated immunity not well received
“Cellularists” were unpopular until the mid 1950s. His proposal was not well receive in the medical community because at the time inflammation was considered to be a harmful process. Also, cell mediated biology was only properly studied wig microbiology techniques - not used till 1950
Who proposed antibody-mediated immunity
Emil Behring
How was antibody mediated immunity published? How was it received
He published observations of “serum factors” could be used to confer immunity to Diptheria. He proposed that the body was defended against invasion by these serum factors (later called antibodies).
- his proposal was very well received
Who proposed the first model for an antibody function and the first cellular model for immune system function
Paul Ehrlich
What was the first model for an antibody function
An antibody and an antibody generating substance (antigen) interacted like a lock and key
What is the side chain theory
All antibody-producing cells are pre programmed to display protein “side chains” (antibodies) against all possible antigens
- antigen binding to a specific antibody induces a cell to synthesize this “selected” antibody to the exclusion of all other antibodies
How were Ehrlich proposals received
Very well
Why is the side chain theory considered a selective theory
The antigen “selects” the appropriate, off the shelf antibody molecule
What did Sir Almroth Wright propose. What did his observations indicate
He noticed that bacteria were only phagocytosed in the presence of serum
- he proposed that bacteria needed to be coated with certain serum factors he named opsonins (which means like relish, salsa)
They indicated That cell mediated immunity and antibody mediated immunity are equally important for protections against microbial infections
What did sir Peter Medawar show regarding transplant rejection
He showed that transplant rejects was a cell mediated process
- this revitalized interest in cell mediated immunity
- which brought money and researchers into immunology
What is the clonal selection theory
Proposed by Jerne, talmadge, burnet
- Individuals continuously produce numerous short-lived, clonally derived lymphocytes
- each clone arises from an individual lymphocyte with a particular, pre programmed antigen specificity - Antigen binds to one of these clonally derived lymphocytes and activates that particular lymphocyte
- lymphocytes proliferate and differentiate into effector cells and long lived memory cells - If no antigen binds to a particular lymphocyte, that lymphocyte will die within a few days
- this intentional high turnover rate allows the immune system to continuously re program and test antigen specificities
Where is the immune system
The lymphatic system
- all immune system cells originate in the lymphatic system. Most of them travel back and forth through the circulatory system and the lymphatic system
What are the functions of the lymphatic system
- Fluid recovery system
- the closed circulatory system is quite leaky- roughly 01% leakage rate (or about 3 L/day)
- the open lymphatic system returns this fluid to the bloodstream
- roughly 01% leakage rate (or about 3 L/day)
- Fat absorption system
- specialized lymphatics called lacteals (=milky ones) project into the villi in the intestines- lacteals contain milky looking lymph containing absorbed fats called chyle (=juice)
- lacteals allow fats to be slowly metered into the circulation. Fats are first packaged into chylomicrons, which are then folded into the circulatory system via the thoracic duct
- lacteals contain milky looking lymph containing absorbed fats called chyle (=juice)
- Immune response system
What are the components of the lymphatic system
Lymph
Lymphatics
Central lymphoid organs
Lymph
Clear extra cellular fluid that leaks from the circulatory system
- lymph does not contain RBCs or most blood proteins
Lymphatics
Thin walled, vein like vessels
Much more permeable to incoming fluids than blood capillaries
- collect lymph from tissue interstices
- the flow of lymph depends on skeletal muscle compression of the lymphatics. One way valves in lymphatics direct the flow. The “pooling” of lymph in your legs and feet is one of the reasons you get so tired during trans-pacific flight (also explains “Hong Kong feet”)
What are the central lymphoid organs
The bone marrow
The thymus
What do the central lymphoid organs do
(General or primary lymphoid organs)
- provide sites for the generation and maturation of lymphocytes
The bone marrow
(B for B cell)
- site for hematopoesis (=create blood)
- site for B cell “maturation”
- all blood cells – and that means all Immune System Cells – are produced by hematopoietic stem cells in the bone marrow
- B cells are produced in specific sites in the bone marrow and undergo an intensive negative selection against self specificity and positive selection for reactivity (“mature”) in other sites in the bone marrow
The Thymus
Site for T cells “maturation”
- T cells are produced in specific sites in the bone marrow but undergo an even more rigorous maturation in the thymus
What are the peripheral lymphoid organs
Spleen
Lymph nodes
What do the peripheral lymphoid organs do
(Secondary lymphoid organs)
Provide sites in the periphery for antigen lymphocyte interactions