enzymes in the serum and modulate enzyme activity or interfere with the binding of polyclonal antibodies to the protein. The addition of polyclonal antibodies to cytosolic AST produced complete inhibition of the enzyme activity

interfere with the binding of polyclonal antibodies to the protein. The addition of polyclonal antibodies to cytosolic AST produced complete inhibition of the enzyme activity (5 ). The proposed immunologic method for measuring AST seems to have potential advantages over the conventional enzyme activity assay. In a single liver cell, two types of AST are present: a mitochondrial and a cytosolic form. The mitochondrial form is released into circulation in cases of more severe liver cell damage (2, 15). Thus, the degree of liver cell injury may be estimated by determining the ratio of serum mitochondrial and cytosolic AST. A higher concentration of mitochondrial AST may indicate more severe liver damage. Another issue to be considered is the degradation of enzymes in the circulation, with loss of activity by denaturation or degradation.