lecture 19 - immunology Flashcards
innate immunity =
recognition of obvious traits shared by a broad range of pathogens. very rapid response, however, if it is new and changing bacteria, you will not be able to identify it. e.g. neutrophils and macrophages
adaptive immunity =
recognition of specific pathogen traits, using a vast array of receptors. slower response and only occurs in vertebrates. Includes both humoral response and cell-mediated response.
humoral response
antibodies defend against infection in body fluids
how many lymphocytes renewed each day?
10^9
lymph nodes
mosaics of B-cell and t-cell clones. Lymph travels through them before re-entering the blood
5 steps to immune response
- immediate inflammatory response
- specific t-helper activation
- specific b-cell activation
- b-cell clonal expansion
- memory update
trigger and cause of localised swelling at infection site (step 1)
triggered by tissue damage, caused by opening of capillary walls.
mast cells
move to infection site, release histamine, which in turn attracts neutrophils.
phagocytic cells involved in the immediate response
neutrophils (not an APC)
then, macrophages/dentritic cells (APC), B-cell (APC),
how do leukocytes move out of blood vessels (not including arteries)?
cytokines released at site of inflammation, increase permeability to WBCs
How leukocytes move through vessels
surface proteins called selectins form weak bonds with carbohydrates on the outside of the WBCs, which allow them to stick and roll slowly through.
Antigen presenting cells (APC)
- phagocytosis of pathogen
- digestion of antigen to peptide fragments
- vesicle with fragments fuse to vesicle with MHC class 2 molecules
- fragments form complex with MHC class 2
- vesicle undergoes exocytosis and complex binds to membrane
aproximate length of peptide antigen fragments
~10 amino acids
alarm #1
dendritic/macrophage cells carry antigen peptides (on membrane) to the lymph nodes, and bind the T-cell clones with the specific TCR - stimulating them to divide.
alarm #2
antigen presenting B-cells arrive at the lymph nodes. Activated T-cells bind to antigen and release interleukin 2 and cytokines, helping the B-cell differentiate. Activated B-cell clones produce huge number of antibodies.
clonal expansion
process where lymphocyte clones divide
auto-immune disease
antibodies bind to your own proteins
T-helper cells function?
assist other cells produce more anti-bodies, OR stimulate formation of cells which can specifically destroy foreign or infected cells
T-cell clones divide into…
memory T-helper cells (long lived) and T-helper clones
B-cell clones divide into
plasma cells (antibody production) and memory B-cells (long lived)
key features of B-cell clonal expansion
- delayed 1-2 weeks
- more effective and specific
- lymph nodes swollen
- huge antibody production
- t-cells still stimulating b-cell production
what eventually happens by the end of the immune response
all bacteria are eventually tagged and killed by macrophages or b-cells
first to develop a vaccine? for which disease?
Jenner. Vaccine for smallpox
second infection features and reasons
rapid response, may not even be noticed that you were ever infected. This is due to increased antibody level in blood and there are now large clones of specific B and T cells in the lymph nodes.
which cells have CD4 proteins?
macrophages and T-cells
what do antibodies do?
tag pathogens for destruction
chemicals released by T-helper cells, encouraging B-cell differentiation
interleukin 2 and cytokines
allergies
Inappropriate or excessive immune responses to antigens
cell-mediated response
Cytotoxic cells defend against infection in body cells.
