Serum Vitamin B₁₂ Binding Proteins in Viral Hepatitis

Abstract

Abstract. Sera from patients with viral hepatitis were examined for serum vitamin B12 concentration, unsaturated B12 binding capacity, total B12 binding capacity of whole serum and of separate transcobalamin‐I and transcobalamin‐II fractions. It was found that the high serum B12 concentrations observed were associated with an increase in the B12 binding of the transcobalamins. The B12 bound to transcobalamin‐I was found to be two to three times higher than that in normal subjects. The most striking difference was the finding of excessive amounts of B12 bound to transcobalamin‐II, as much as 30 to 40 times the normal. The unsaturated B12 binding capacity of hepatitis sera is usually very low. In addition to the B12 bound to transcobalamins, a considerable part of the elevated serum B12 in hepatitis was in a dialyzable form and was not bound to either transcobalamin‐I or transcobalamin‐II. This dialyzable B12 is apparently bound to a small peptide (M.W less than 10000) which permits its passage through dialysis membrane but makes the B12 molecule unavailable to the microorganism in the bioassay, unless it is released from the peptide complex by boiling.

Chronic Eosinophilic Leukemia Complicated by Epidural Myeloblastoma

“…The most important change was the decrease in the TC I and increase in the TC II associated with re duction in the bound serum B12. The latter findings were observed in hepatocellu lar damage [ 16].…”

Increased Serum Corrinoids Correlates with Disease Severity and IgA Levels in Alcoholic Cirrhosis

“…An in crease in plasma vitamin B12 levels has also been reported in other liver disorders, e.g. viral hepatitis [12,24] and alcoholic hepati tis where hepatic cytolysis is a common fea ture [5], In the same way, Baker et al [5] observed recently that high plasma vitamin B12 levels correlated significantly with the standard liver function tests, including bili rubin, cholylglycin, alkaline phosphatase, al anine serum transferase and prothrombin time, in case of alcoholic hepatitis. They concluded that the increased plasma vitamin B12 levels were correlated to the severity and the mortality of alcoholic hepatitis.…”

“…Rachmilewitz et al [12] have shown that induced liver injury in dogs and rats results in a release of Cbl from damaged hepatocytes. This may account for elevated serum Cbl [6,7], Moreover, the ability of the alco holic liver to store vitamin may be impaired in alcoholic cirrhosis [23], In our study, the levels of total corrinoids and of true Cbl in IVC, SHV and SVC from 27 cirrhotic pa tients were significantly higher than in con trols and they increased with the degree of severity of the disease, estimated by the Child-Pugh classification ( fig.…”

“…The increased level of corrinoids in the serum of patients with cirrhosis or alcoholic hepatitis could be explained in two ways, the failure of the damaged liver to take up Cbl and analogues from the serum and/or the release of corrinoids and corrinoid binders from the liver into the serum [12,23]. The first of these two hypothetical mechanisms could explain that a significant correlation was observed between the level of corrinoids bound to He in the IVC and the level of IgA (r = 0.59; p < 0.02).…”

“…These findings have been linked to the release of Cbl and of Cbl binders from hepatic stores to the circulation [7,9,10], Baker et al [4,11] observed a decreased excretion of intramuscularly administered Cbl in case of hepatic insufficiency. Rachmilewitz et al [12] have shown that induced liver injury in dogs and rats resulted in a release of Cbl from damaged hepatocytes. Moreover the ability of the alcoholic liver to store the corrinoids may be impaired in alco holic cirrhosis [13].…”