- Each antigen may have many different determinants .
- Antigen interacts with the surface of sensitized mast cells .
- The second group of antigens consists proteins and nucleoproteins .
- The immunogenic potency of soluble antigens may be considerably increased .
- There are numerous inherited antigens on the surface of the human erythrocyte .
- any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies)