These cells recognize antigen plus type II MHC molecules. Their role is to help B cells make antibody or to help cytotoxic T cells kill foreign antigen-containing cells. Click HERE for an illustration of cell interactions in antibody formation. This is also diagrammed in Fig 17.15. The antigen is taken in by an APC and processed, or partially broken down.
Determinants are still intact.
A CD4 helper T cells that is able to recognize this antigen-MHC complex binds . Ig receptors specific for different determinants on the same antigen. This triggers the B cells to differentiate into a plasma cells and to make antibody. LPS and capsule polysaccharides are good examples. T independent antigens can only stimulate the production of IgM, not IgG. 2.