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When the immune system does not respond to a particular antigen?
Tolerance exists when the immune system does not respond to a particular antigen. All cells and tissues in the body contain antigens that normally do not stimulate an immune response. The immune system is said to exhibit tolerance toward such antigens.
In order for a lymphocyte to respond to an antigen the antigen must?
the antigen must bind to the receptor
When IL-2 is secreted by antigen-specific T cells activated due to presentation of antigen by APCs What happens to naive antigen-nonspecific T cells in the vicinity?
Naive antigen-nonspecific T cells do not become activated since they lack the T cell receptor specificity for the particular antigen being presented. They do not respond to IL-2 secreted by the activated antigen-specific T cells and remain in a resting state until they encounter an antigen to which they are specific.
How do B cells respond to the initial antigen challenge?
B cells respond to the initial antigen challenge by producing progeny cells. The progeny cells include both memory cells and plasma cells.
To what do antibodies respond?
Antibodies are secreted by a special group of white blood cells called lymphocytes. Each type of cell (including bacteria) has a unique protein on its cell membrane - an antigen. If a lymphocyte does not recognise a particular antigen, it will assume that the cell (or bacterium) is foreign and hostile. This is what antibodies respond to - the stimulus as the result of an unfamiliar cell. The antibodies attach to the antigens and kill the cell, or bacterium.
What does reactive HBs antigen mean?
HBs antigen is an acronym for Hepatits B like antigens found in the blood cells They are the ones that assist the body to respond to any foreign antibody pertaining to that antigen.
What is immunologic memory produced by vaccination?
Immunological memory is the ability of immune system to respond more rapidly and more effectively to pathogens that have been encountered previously and reflects the preexistence of a clonally expanded population of antigen specific lymphocytes.
How do cells involved in the humoral response respond to antigen presentation on the surface of a B cell?
Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies.
Alloreactivity is a positive selection step or negative selection step?
Neither. Alloreactivity has to do with a lymphocytes reacting to a foreign antigen. Positive and negative selection are processes of central tolerance which is to say that they deal with a T cell's ability to bind self-antigen.
What is the ability to respond to stimulus called?
The ability to respond to a stimulus is called irritability or responsiveness. It refers to an organism's ability to detect and react to changes in its environment.
In the primary response to an antigen the first class of antibody to be secreted is?
The class of immunoglobulin to respond to the fist exposure of an antigen is immunoglobulin class M (IgM). While Immunoglobulin G (IgG) would predominate on the second exposure.
Why can type O blood be donated to anyone?
It contains neither A antigen nor B antigen. their blood can be given to individuals of any other blood group red cells do not carry either A or B antigen and hence they do not react with their corresponding antibodies. Remember that an immune respond can only be trigger when the antigen is present in the blood. In another word the blood originally have no any antibody but upon antigen contact it will trigger the immune respond thus antibody is produced and agglutination of blood occur. for rhesus factor there are memory cell so the antibody is still present. That is why when an O blood group without any antigen and antibody (it have both antibody but it is not create yet as there is nothing to trigger its immune respond) can donate to AB group which has no antibody (which mean it will not be trigger by any blood group) but have both antigen (remember that all donated blood have no antibody as there is no immune respond to trigger it thus the AB blood with both antigen is fine; except rhesus factor if it have memory cell)
