adjuvant Any substance that enhances the immune response to an antigen with which it
is mixed.
afferent lymphatic vessels Vessels of the lymphatic system that drain extracellular fluid from the tissues
and carry antigen, macrophages, and dendritic cells from sites of infection to
lymph nodes or other peripheral lymphoid organs.
affinity maturation The increase in affinity for their specific antigen of the antibodies produced as
an adaptive immune response progresses. This phenomenon is particularly
prominent in secondary and subsequent immunizations.
allergy The state in which a symptomatic immune reaction is made to a normally
innocuous environmental antigen. It involves the interaction between the
antigen and antibody or primed T cells produced by earlier exposure to the
same antigen.
allograft rejection The immunologically mediated rejection of grafted tissues or organs from a
genetically nonidentical donor. It is due chiefly to recognition of nonself MHC
molecules on the graft.
, Janeway's Immunobiology Chapter 1 Exam
anergy A state of nonresponsiveness to antigen. People are said to be in this state
when they cannot mount delayed-type hypersensitivity reactions to a test
antigen, whereas T cells and B cells are said to be in this state when they
cannot respond to their specific antigen under optimal conditions of
stimulation.
antibody A protein that binds specifically to a particular substance—called its antigen.
Each of these proteins has a unique structure that enables it to bind specifically
to its corresponding antigen, but all of these proteins have the same overall
structure. These proteins are produced by differentiated B cells (plasma cells)
in response to infection or immunization, and bind to and neutralize pathogens
or prepare them for uptake and destruction by phagocytes.
antigen Any molecule that can bind specifically to an antibody or generate peptide
fragments that are recognized by a T-cell receptor.
antigen-binding site The site at the tip of each arm of an antibody that makes physical contact with
the antigen through the means of a noncovalent interaction. The antigen
specificity of the site is determined by its shape and the amino acids present.
antigenic determinant That portion of an antigenic molecule that is bound by the antigen-binding site
of a given antibody or antigen receptor; it is also known as an epitope.