5.8 Initiation of an adaptive immune response

helper T cells

a class of T cell that bind to an antigen-MHC-II complexes on antigen presenting cells and activate B cells and cytotoxic T cells

clones

groups of cells, organisms or genes with identical genetic make-up

clonal selection

an event occurring in lymph nodes in which those lymphocytes with receptors that can recognise a new antigen come into contact with that particular antigen

clonal expansion

a process of multiple cycles of cell division of a lymphocyte specific to a particular antigen, resulting in the production of large numbers of identical lymphocytes

T cell receptors

a molecules found on the surface of T cells that is responsible for recognising fragments of antigen as peptides bound to MHC molecules