 Antibodies are protein components of an adaptive immune system whose main function is to bind <unk> , or foreign substances in the body , and target them for destruction . Antibodies can be <unk> into the extracellular environment or anchored in the membranes of specialized B cells known as plasma cells . Whereas enzymes are limited in their binding affinity for their substrates by the necessity of conducting their reaction , antibodies have no such constraints . An antibody 's binding affinity to its target is extraordinarily high . 
