By definition an immune system is specific to a single antigen which creates it, however, many naturally occurring'antigens' are a mixture of macromolecules (e.g. bacteria, toxins, proteins, pollen, fungi, viruses, etc) which contain several epitopes.
An immune system is specific to a single antigen, many naturally occurring'antigens' are a mixture of macromolecules (e.g. bacteria fungi etc). This is by definition. This is however. These macromolecules (e.g. bacteria fungi etc) contain several epitopes. This single antigen creates it. E.g. bacteria fungi are viruses. E.g. bacteria are toxins. Toxins are proteins. Proteins are pollen.