What is a true penicillin allergy? First some pathophysiology.
Penicillin is simple in structure and of low molecular weight.
Low molecular weight substances that are able to illicit an immune response are called haptens.
Alone, haptens cannot cause an immune response and must bind to native proteins in the plasma and cell surfaces to form hapten-carrier complexes.
These complexes form antigens that IgE recognizes.