week 2 Flashcards
What are lymphoid progenitor cells?
- can mature into various types of lymphocytes
- eg T, B NK cells
What are myeloid progenitor cells?
- arise from bone marrow
- cells that produce neutrophils, monocytes, eosinophils, and basophils
What is adaptive immunity?
B and T cells mount a response against antigens
How do immune cells communicate?
cytokines
What is the function of chemokines?
attract leukocytes to site of inflammation
What are cytokines?
chemical messengers
What are the three important features of adaptive immunity?
Specific, systemic, memory
What are B cell receptors?
antibodies
What happens after a B cell binds to a foreign substance
proliferation and differentiation.
What happens to B cells after they differentiate?
Become plasma cells that secrete antibody molecules
What are T cell receptors called?
T cell receptors
What are the two types of T cells?
Helper T cells and Cytotoxic T cells
What is the difference between helper T cells and cytotoxic T cells?
CD8 on cytotoxic and CD4 on helper
What is the role of helper T cells?
release cytokines to activate B and T cells
What is a complete antigen?
Antigen with immunogenicity
What is an incomplete antigen?
A non-immunogenic substance
What is immunogenicity?
ability to provoke an immune response
What are examples of complete antigens?
foreign protein, polysaccharides, lipids, and nucleic acids
What are examples of incomplete antigens?
peptides, nucleotides, hormones
How would an incomplete antigen stimulate an immune response?
it can bind with proteins to form complexes that create a response
What are antigen determinants?
certain parts of an antigen that are immunogenic.
Why do antigens need to be processed?
To create a tolerance
What are the two sources of antigens?
Foreign and Body cells
How are exogenous antigens processed?
Phagocytosis. Once it is inside the lysosome it combines with class II molecules and then it is released by exocytosis.
Who are exogenous antigens presented to?
Helper T cells
How are endogenous antigens processed?
broken down into fragments that are taken to the rough ER. They combine with MHC class I molecules and is then transported to the plasma membrane
Who are endogenous antigens presented to?
Cytotoxic T cells
MHC Class 1 Molecules are found
On all nucleated cells
MHC Class 2 Molecules are found where?
Antigen presenting cells eg. macrophage + dendritic cells
Describe the B cell response to antigens
binds to antigen, proliferates, differentiates into plasma cells which secrete antibodies for that specific antigen.
How do helper T cells help B cell activation?
They release interleukins that cause the B cells to divide more rapidly.
What is isotope switching?
cells can change which isotype of antibody they produce
What is the alternative name for antibodies?
Immunoglobins
What cells produce antibodies?
B cells
Name the components of antibodies
heavy chain, light chain, variable region, flexible hinge, constant hinge and disulphide bonds.
What are IgM immunoglobulins?
first and largest antibody to be produced
What are IgA immunoglobulins?
protection of mucosal surfaces
What are IgD immunoglobins?
found on cell membrane of B cells
What are IgG antibodies?
placental transfer, breastmilk, plasma
Most abundant
What are IgE immunoglobins?
triggers inflammatory response, hypersensitive, parasites
What is an immune complex?
an antibody bound to an antigen
What is the compliment interaction
antibody binds to an antigen and causes the membrane attacking complex leading to cell lysis
What is the CD molecule for helper T cells
4
What class is helper T cells
class II
Are helper T cells for inside or outside of the cell antigens
outside
What CD molecule are Cytotoxic T cells?
8
What class are cytotoxic T cells
class I
Are cytotoxic T cells for outside or inside of the cell antigens
inside
When are helper T cells activated?
When they recognize an MHC class II complex
What happens after a helper T cell recognizes it’s complex?
A cosignal is released from CD4 which increases the cytokine receptors.
What happens once an T cell is activated
it proliferates and differentiates into cytotoxic T cells or Helper T cells
What are two mechanisms that Cytotoxic T cells use?
cytokines for adoptosis and perforin for cell lysis.
What happens to cytotoxic T cells once it has destroyed its target?
It detaches itself from the infected cell
What is the importance of immunucompetence?
It ensures an accurate immune response while protecting body tissues
During immunocompetence what percent of T cells survive?
1-3
During immunocompetence what percent of B cells survive?
25-45
Why is it important for lymphocytes to undergo immunocompetence training?
So that they don’t attack our own tissues
What is positive selection?
T cells that don’t bind to MHC molecules are eliminated
What is negative selection?
T cells that strongly bind to self antigens undergo apoptosis
What is central tolerance?
Occurs during the development of lymphocytes
What is peripheral tolerance?
occurs for matured immune cells in the spleen and lymph nodes.
What happens to cells that fail training
apoptosis
Function of cytotoxic T cells
Recognise none self antigens on MHC 1 markers of pathogen and produce cytoxic chemicals (Perforins) that destroy the target cell by causing holes in the plasma membrane
Directly killing infected or cancerous cells
4 functions of antibodies
- Neutralization
- antibodies block sites on viruses so that they lose their toxicity. - Opsonisation
- coating pathogens with antibodies, making them more recognisable to phagocytic cells - Agglutination
- antibodies cause antigens to clump together for easier phagocytosis - Precipitation
- antibodies bind multiple soluble antigens and form a large mass
colonal selction
The specific and complementary T helper cell is selected when an antigen presenting cell presents a non-self antigen to it. This T helper cell secretes cytokines to active a B cell. This B cell is then selected as it recieves this cytokine and it’s membrane bound antibodies bind to the non-self antigen presented by an antigen presenting cell.
This occurs in the lymph node
colonal diffrentiation
B lymphocytes divide to become either Plasma cells or B memory cells
colonal expansion
When the B cell has attached to the antigen it then rapidly divides by mitosis forming plasma cells and B memory cells
What is the function of a plasma cell?
Plasma cells produce specific and complementary free-floating antibodies
What is the function of a B memory cell?
Remain in circulation after the pathogen has been dealt with and when the same pathogen is encountered again, they divide by mitosis more rapidly forming Plasma cells and more B memory cells. This leads to a higher concentration of anitbodies.
How does the secondary immune response differ from the primary immune response?
The secondary immune response has a more RAPID production in the secondary response, and a HIGHER CONCENTRATION of antibodies
