Expression of HL-A Antigens on the Surface of Cultured Human Lymphoid Cells: Effect of Inhibitors of Protein and Nucleic Acid Synthesis

Cultured human lymphoid cells (WI-L2), when incubated in mid-log phase with different concentrations of puromycin, showed a 70% decrease in the expression of HL-A antigens on their surface as measured by quantitative microabsorption. This decrease in surface antigen expression was accompanied by a marked inhibition of the rate of incorporation of ¹⁴C leucine into cellular polypeptides suggesting a correlation between protein synthesis and HL-A antigen expression on cultured human lymphoid cells. The inhibitory effects of puromycin on HL-A expression were reversible. Actinomycin D did not affect HL-A antigen expression, suggesting that the messenger RNA coding for these antigens is relatively long-lived. Cytosine arabinoside, 5-bromodeoxyridine, ethidium bromide and rifampicin did not affect HL-A antigen expression. By contrast, cycloheximide at a concentration which inhibited the rate of polypeptide synthesis by at least 95% did not change HL-A antigen expression. The differential effects of puromycin and cycloheximide on the synthesis of HL-A polypeptides are similar to the effect of these drugs on mitochondrial protein synthesis.     

The association between rifamycin-SV (R-SV) related hyperbilirubinaemia and antipyrine clearance as a new test of liver function in cirrhosis

Abstract. Several clearance tests have been used to assess the residual hepatic efficiency in liver cirrhosis. However, the altered clearance values found in cirrhotic patients may reflect not only the impairment in liver function but also a derangement in the hepatic blood-flow. Therefore, this study was designed to explore the possibility that the competition between Rifamicyn-SV and bilirubin at the hepatic uptake site might be used as an index for quantitative assessment of residual hepatic efficiency in 48 patients with chronic liver disease. In this test, the interference of hepatic blood flow would be negligible. Antipiryne clearance was also evaluated in the same subjects in order to explore the cytoplasmic microsomial efficiency. Rifamicyn-SV intravenous load was followed by a sustained increase in bilirubinaemia which significantly related with the degree of liver function as assessed by the Chil-Pugh criteria. Also, antipiryne clearance was significantly altered in cirrhotic patients compared to controls. Moreover, a positive correlation was found between the Rifamicyn-SV test and Antipiryne clearance. We suggest that a combination of these tests might be of use in the quantitative assessment of liver function.