 In this way, it mediates different physiological effects of antibodies (detection of opsonized particles; cell lysis; degranulation of mast cells, basophils, and eosinophils; and other processes).In a new development in the field of antibody-based therapeutics, the Fc region of immunoglobulins has been engineered to contain an antigen-binding site.This type of antigen-binding fragment is called Fcab.