In Vivoandin VitroEffects of Antiinsulin Receptor Antibodies*

Abstract

We studied a patient with Acanthosis nigricans and the type B syndrome of severe insulin resistance. The patient's rates of basal glucose disappearance and appearance were both normal (2.2 and 1.7 mg/kg . min, respectively). FFA, betahydroxybutyrate, and acetoacetate concentrations were stable at 0.8, 1.0, and 0.3 mM, respectively, during a 2-h saline infusion after an overnight fast, indicating continued presence of insulin-like activity (ILA) in her serum. Infusion of insulin at rates of 2.7 and 27 U/h, raising peripheral insulin concentrations from 1400 to 4000 and 6000 microU/ml, respectively, had no effect on glucose disappearance and appearance or plasma concentrations of beta-hydroxybutyrate, acetoacetate, and FFA, suggesting that the observed ILA was not caused by the patient's plasma insulin. To determine the source of the ILA we used the patient's serum containing antiinsulin receptor antibodies (AIRA) to study its acute (2 h) and chronic (24 h) effects on insulin binding and glycogen synthesis in rat hepatocytes in primary culture. Preincubation of hepatocytes with AIRA serum (diluted 1:100) inhibited insulin binding by 84% and 88% after 2 and 24 h, respectively. It increased U-[14C]glucose incorporation into glycogen by 40% and 52% after 2 and 24 h, respectively. These effects were not caused by insulin present in the patient's serum. We conclude that AIRA serum, in addition to causing severe insulin resistance through inhibition of insulin binding, also exerted strong and long lasting insulin-like effects. These findings are compatible with the patient's clinical features of absence of ketoacidosis despite severe insulin resistance, decrease in glucose concentrations during fasting, and postprandial hyperglycemia.

Lipid-Induced Insulin Resistance in Human Muscle Is Associated With Changes in Diacylglycerol, Protein Kinase C, and IκB-α

“…3 H]glucose specific activity as described (25). Rates of total body glucose appearance (G Ra ) and disappearance (G Rd ) were calculated using Steele's equation for non-steady-state conditions (26).…”

Effects of Free Fatty Acids on Glucose Uptake and Utilization in Healthy Women

“…Measurements. Glucose turnover was determined with [3-3 H]glucose as previously described (12). [3-3 H]glucose infusion (a bolus of 40 Ci followed by a continuous infusion of 0.4 Ci ⅐ min Ϫ1 ⅐ 6 h) was started 2 h before initiation of the clamp to assure isotope equilibration.…”

“…[3-3 H]glucose infusion (a bolus of 40 Ci followed by a continuous infusion of 0.4 Ci ⅐ min Ϫ1 ⅐ 6 h) was started 2 h before initiation of the clamp to assure isotope equilibration. Glucose was isolated from blood for determination of [3-3 H]glucose specific activity as described (12). Changes in specific activity due to infusion of unlabeled glucose were prevented by addition of the isotope to the unlabeled glucose infused to maintain euglycemia.…”

Nonbinding inhibitory antiinsulin receptor antibodies. A new type of autoantibodies in human diabetes.

“…Hepatocytes were isolated by in situ collagenase digestion of livers from fed Sprague-Dawley rats (200-300 g). Primary cultures of rat hepatocytes were prepared as described previously (10).…”

“…Insulin binding to hepatocytes was examined as described (10). Briefly, hepatocytes in monolayer (2 X 106 cells/25 cm2 flask) were preincubated with sera from the various study groups for 2 h at 370C, then washed twice with Krebs-Ringer bicarbonate (KRB) buffer.…”