Re: what is antigenic activity?

Antigenic activity is the ability of a chemical compound (usually a 
protein or peptide) to elicit an immune response in a host. The large 
number of clonal variants in the host and the ability of those clones to 
mutate allow the host to respond to virutally an unlimited number of 
antigens. The antigens are taken up by the host by a number of different 
means and are processed by the immune system. Usually this involves 
phagocytosis and partial digestion by macrophages. The processed antigen 
is then presented to immune compartment cells (T cells and B cells), which 
clonally expand in response to activation. The presentation of antigen can 
occur in the gut or other mucosal lymphoid compartments. The activated 
immune cells are often expanded in regional lymph nodes.