Studies on enzyme-linked immunogloblins

II. Amylase-linked immunoglobulin

Abstract

Many cases of macromolecular amylases were reported. Various modes of complex formation with normal amylase were considered to be categorized as follows: 1. a polymer complex of normal amylases, 2. a complex of normal amylase and plasma proteins other than immunoglobulins (e. g., some glycoproteins), 3. a complex of normal amylase and some other large non-protein molecules (e. g., glycogen or other mucopolysaccharides) and 4. a complex of amylase and immunoglobulins.
In this study, four cases of amylase-linked immunoglobulins were reported and the mode of binding form between amylase and immunoglobulins were discussed.
Three of the cases were tumor-bearing patients of lung, gastric and esophageal cancer, and therapeutically, pancreatic enzyme preparations were not administered in the past three years. The last one was a patient with liver cirrhosis and chronic pancreatitis who have not been administered with pancreatic drugs.
The class of heavy chain of amylase linked immunoglobulin was proved to be γ in three and α in one of the cases by immunoelectrophoresis followed by amylase activity staining. The type of light chain was determined to be exclusively λ irrespective of heavy chain class.
In three of the cases, the immunoglobulin complexes were partially dissociated into normal amylase and immunoglobulin G at pH8.6, and completely dissociated at pH9.0. These phenomena of dissociation might give a clue to explain the heterogeneity of macromolecular amylases which have been discussed previously.
Papain digestion of amylase linked immunoglobulin G was carried out to elucidate the specific antigen-antibody bindings of these macromolecular complexes. The molecular size of the digest was determined to be smaller by thin layer gel-filtration. The precipitin line formed against anti-Fab antiserum was proved to have amylase activity, but that against anti-Fc was not. This fact suggests that the binding site of amylase linked immunoglobulin G was located in Fab portions and that the complexes are specific antigen-antibody complexs.
Thus, it was elucidated that the complex formation of amylases and immunoglobulins in blood plasma is one of the circulating autoantibodies and must be clearly distinguished from the other unknown macromolecular amylase complexes.