The difference between antigens vs. haptens is one the most concerning issues for people who are not familiar with them. As a matter of fact, antigens and haptens are similar in many ways. They are both molecules triggering immune responses and acting as antigenic agents. And they both work as immunogens and bind to antibodies although haptens in a different manner. What distinguishes an antigen mostly from a hapten is that antigens are complete molecules spontaneously triggering immune response whereas haptens are fragmentary small molecules that are unable to elicit immune responses unless they are conjugated to a larger molecule, known as a carrier. What are Antigens? Antigen s, including proteins, peptides, and polysaccharides, are immunogen molecules that can trigger immune response s or naturally bind to immune components . An antigen may have one or more epitopes, which are the determinants of recognition and binding to antibod...