Antibody-mediated suppression of the immune response is determinant specific

It was studied whether antibody-mediated suppression of the immune response was determinant specific. Fluorescein isothiocyanate (FITC)-conjugated sheep red cells were used as the immunogen and antibodies were raised both against the carrier sheep red cells and the hapten FITC. When these antibodies were injected 1-3 h after the immunogen they only suppressed the immune response to the corresponding determinant. Anti-carrier antibodies usually enhanced the response to the hapten. Therefore, antibody-mediated suppression of the immune response is determinant specific and cannot be mediated in vivo to a detectable extent by the Fc part of the antibodies.