4.1.1 f lymphocytes Flashcards
where do t lymphocytes mature?
thymus glands
where do b lymphocytes mature?
bone marrow
where are t lymphocytes made?
bone marrow
where are b lymphocytes made?
bone marrow
what type of immunity do t lymphocytes provide?
cell-mediated
what is cell-mediated immunity?
t lymphocytes respond to the cells of an organism that have been changed in some way
what type of immunity do b lymphocytes provide?
humoral immunity
what is humoral immunity?
body responds to antigens found outside the cells
what do t lymphocytes respond to?
own cells that have been altered by viruses or cancer and to transplanted tissue
foreign materials inside body cells
what do b lymphocytes respond to?
foreign materials outside body cells
bacteria and viruses
what happens first for cell-mediated immunity?
macrophages engulf and digest the pathogens in phagocytosis
they process the antigens from the surface of the pathogen and form antigen-presenting cells
what is the role of a T helper cell?
have CD4 receptors on their cell surface membranes which bind to the antigens on the antigen presenting cells
produce interleukins which signal and stimulate the activity of B cells to increase antibody production and also stimulates production of other types of T cells and attracts and stimulates the macrophages to ingest pathogens
what is the role of a T killer cell?
destroy pathogen carrying the antigen by producing perforin which kills pathogens by making holes in the cell membrane so it is freely permeable
water gets in, cell bursts
what do T memory cells do?
live for a long time
part of immunological memory
if they meet an antigen for the second time, they divide rapidly to form a huge number of clones of T killer cells that destroy the pathogen
what do T regulator cells do?
cells suppress the immune system
stop the response once a pathogen has been eliminated and make sure the body recognises self antigens and does not set up an autoimmune response
interleukins are important in this control
what do plasma cells do?
produce antibodies to a particular antigen and release them into circulation
what do B effector cells do?
divide to form the plasma cell clones
what do B memory cells do?
live a very long time and provide an immunological memory
programmed to remember a specific antigen and enable the body to make a very rapid response when a pathogen with that antigen is encountered again
what is the second stage of cell-mediated immunity?
receptors on T helper cells fit the antigens
T helper cells become activated and produce interleukins which stimulate more T cells to divide rapidly by mitosis
form clones of identical activated T helper cells that all carry the right antigen to bind to a particular pathogen
what can the cloned T cells do?
develop into T memory cells
produce interleukins that stimulate phagocytosis OR stimulate B cells to divide
stimulate the development of a clone of T killer cells that are specific for presented antigen and then destroy infected cells
what is clonal selection?
activated T helper cells bind to the B cell APC and the B cell with the correct antibody that can overcome a particular antigen is selected for cloning
what is the first stage of humoral immunity?
clonal selection
what is the second stage of humoral immunity?
interleukins produced by activated T helper cells activate the B cells
what is the third stage of humoral immunity?
activated B cell divides by mitosis to give clones of plasma cells and B memory cells which is clonal expansion
what is the fourth stage of humoral immunity?
cloned plasma cells produce antibodies that fit the antigens on the surface of the pathogen and bind to the antigens to disable them or act as opsonins or agglutinins
primary immune response
what is an opsonin?
proteins attached on the outside of cells and pathogens to tell phagocytes to engulf them
what are agglutinins?
causes particles to coagulate to make them using to engulf a number of them at the same time
what is the last stage of humoral immunity?
some cloned B cells develop into B memory cells
if body is infected by same pathogen again, B memory cells divide rapidly to form plasma clone cells which can produce the right antibody and wipe out the pathogen very quickly
secondary immune response
