B Cells and antibody production Flashcards Preview

Medsci 202 > B Cells and antibody production > Flashcards

Flashcards in B Cells and antibody production Deck (25)
Loading flashcards...

What do the immune and adaptive immune processes depend on?

Blood cells- produced in the marrow of our long bones from stem cell precursors. These blood cells perform immune functions.


What are the blood cells produced by these stem cells called?



What other cells are produced from megakaryocyte?

1. Platelets-clotting factors
2. B cell and T-cell
3. Eosinophil
4. Monocyte= macrophage
5. Basophil
6. Neutrophil
7. Red cell


What are the two primary lymphoid organs?

1, Bone marrow
2. Thymus


What do primary lymphoid organs do?

Makes lymphocytes
1. Bone marrow- B lymphocytes
2. Thymus- T lymphocytes


What are the secondary lymphoid organs called?

Spleen, lymph nodes, tonsils, adenoids, Peyer's patches, Skin


What do the secondary lymphoid organs do?

Lymphocytes in the primary lymphoid organs migrate here
-Filter foreign matter out of the body fluids
-Carry out immune responses to foreign antigens.


How are primary and secondary lymphoid organs connected together and to the rest of the body's tissues?

By blood and lymphatic vessels, through which fluids and cells are constantly flowing.


How much of the total body lymphocytes are circulating at any one time?



What is the circulatory pathway of lymphocytes?

1. Lymphocytes leave the bloodstream, squeezing through capillaries called high endothelial venules(HEV), and entering tissues such as lymph nodes.
2. They accumulate in small lymphatic vessels that connect to a series of lymph nodes downstream.
3. Passing through larger and larger vessels the lymphocytes enter the main lymphatic vessel- thoracic duct which carries them back into the blood.


What is the purpose of continuous recirculation of lymphocytes?

Ensures that the appropriate lymphocytes will come into contact with antigen and with each other to disperse the activated lymphocyte cells throughout the body's tissues.


What are the two subpopulations of lymphocytes?



What are the are the effector and regulator subpopulations responsible for?

Effector- Recognizing, responding to and disposing of antigenic substances.
2. Primarily involved in controlling of the effector functions.


What are the effector responses and the lymphocytes responsible for it?

1. Antibody production(B lymphocytes)= main one
2. Antigen specific cytotoxicity (CD8 T lymphocytes)= main one
3. ADCC- Antibody dependent cell mediated cytotoxicity(K cells)
4. Natural killer cells activity( NK cells)


What are regulatory responses and the lymphocytes responsible?

1. Cytokine production( CD4 lymphocytes)
2. Helper cells(TH1- viruses, bacteria and TH2-parasites, allergies)
3. Treg- downregulation of responses.


What is a primary immune response?

1.Occurs when an antigen is present, which has not been previously encountered by the adaptive immune system.
2. There is a lag period of a few days before effectors(antibodies or cytotoxic T lymphocytes) specific for that antigen appear in the blood.
3. These effectors can bind to antigens and lead to their neutralisation or removal.


What is called a secondary response?

If we are exposed to the same antigen that has been dealt with before by the immune system, then the response is much more rapid and vigorous than the primary response. This is due to immunological memory.


What are antibodies or immunoglobulins made of?

>Four polypeptide chains held together by disulphide bonds and non-covalent interactions.
> 2 heavy and 2 light chains in a covalently bonded structure with globular domains and variable and constant regions.


How do B cells generate an antibody response?

1. Antigens select and bind to antigen-sensitive B lymphocytes that have surface immunoglobulin receptors with appropriate affinity.
2. Helper T cells provide these virgin B lymphocytes with further activation signals
3. Activation of these B lymphocytes results in proliferation of plasma cells which secrete soluble antibodies of the same antigen-binding specificity as was present on the surface immunoglobulin of B cell.
4. A population of memory cells is also produced as a result of this clonal activation and expansion process.


Why are memory cells useful?

>Produce more rapid and larger responses.
> more long-lived than precursor B cells
> replace the B cells
>Don't need helper cells to identify danger
> make memory cells in case the antigen comes back-the immune system can recognise it.
> they circulate so the memory of the antigen goes to other organs.


How do antibodies work within the body?

1. Direct neutralisation
2. Complement activation
3. Opsonisation
4. Antibody-dependent cell mediated cytotoxicity.


How does direct neutralisation work?

Antiviral antibodies prevent virus adsorption


How does complement activation work?

>Antigen bound to antibody(antigen-antibody complex) activates the complement system
>The complement system is a series of proteins that act in an enzymatic cascade.
> Activation of the complement system is important in destroying foreign material due to
: Chemotaxis- Attraction of phagocytic cells to the site of complement activation(where bacteria are)
: Opsonisation- Enhancement of the phagocytic process.
:Lysis- Destruction of cell membranes


How does opsonisation work?

Phagocytic cells possess cell surface receptors for the Fc region of antibody molecules
> therefore the antigen cannot bind directly to these but the use of these receptors is to bind with high affinity to the antibody carrying the antigen.


How does antibody-dependent cell-mediated cytotoxicity occur?

Through K cells.
K cells have Fc receptors so they can bind the antibody to itself-the antibody has the foreign material attached to it.
> K cells are not phagocytic but they are able to kill the cellular material(bacteria) which they become bound to through the antibody. They kill them by releasing short range cytotoxicity factors.