Depending on the route of administration, different cell populations will respond. Adjuvants Substances used together with the antigen to increase the immune response. They prolong the persistance of the Ag at the site of administration, induce granuloma formation, and stimulate immune cells nonspecifically. Granuloma - a cellular infiltration at the site of injection, due to the use of adjuvants. B cells bind free Ag in solution.
Some epitopes are immunodominant because they induce a stronger immune response.
Conformational determinants are formed by amino acids found at different positions in the primary structure, but brought into close contact by the tertiary structure. Abs raised against the loop present in the hen edd-white lysozyme react with a synthetic closed loop, but not with the synthetic open loop. The part of the antigenic peptide that binds to the T cell receptor is called epitope and the part of the antigenic peptide that binds to the MHC molecules is called agretope. Class I MHC bind peptides formed by 8-11 aminoacids, with the highest affinity for 9 aminoacids. Class II MHC bind peptides formed by 12-25 aminoacids.