 The exact nature of antibody-antigen interaction in autoimmune disease is not yet understood..

Antigen-antibody interaction is used in laboratory techniques for serological test of blood compatibility and various pathogenic infections.The most basic is ABO blood group determination, which is useful for blood transfusion.Sophisticated applications include ELISA, enzyme-linked immunospot (Elispot), immunofluorescence, and immunoelectrophoresis.