(blocking antibody) An antibody that binds to endogenous or exogenous compounds and inhibits the biological activity of that compound.

(blocking antibody) Antibody which interferes with the reactivity of the others by binding available epitopes of homologous specificity; or, univalent antibody that can coat antigen bearing cells but not agglutinate them.

Antibodies that inhibit the reaction between ANTIGEN and other antibodies or sensitized T-LYMPHOCYTES (e.g., antibodies of the IMMUNOGLOBULIN G class that compete with IGE antibodies for antigen, thereby blocking an allergic response). Blocking antibodies that bind tumors and prevent destruction of tumor cells by CYTOTOXIC T-LYMPHOCYTES have also been called enhancing antibodies. (Rosen et al., Dictionary of Immunology, 1989)