Does an antigen have to be derived from foreign cells What i

Does an antigen have to be derived from foreign cells? What is the difference between an antigen and an epitope?

Solution

Antigen is defined as a substance that triggers an immune reaction in an organism. Though antigens are typically derived from foreign cells, they may also be derived from the body\'s own cells, triggering an autoimmune reaction.

An epitope is a part of an antigen, which is otherwise known as \"antigenic determinant.\" Epitopes are identified by the immune cells such as antibodies and B cells. Loss of epitopes results in loss of antigenicity.