Effect of varying LA IgG concentration on thrombin production in the phospholipid-coated flow reactor. Glass capillaries were coated with phospholipid vesicles and incubated with 0.1 μmol/L prothrombin, 0.1 nmol/L factor Va, and 5 to 50 μmol/L control or LA IgGs for 1 hour. The capillaries were perfused with 20 pmol/L factor Xa at a flow rate of 30 μL/min. Total thrombin production was calculated for each LA IgG concentration from the area under the curve of profiles of the type shown in Fig 4. Thrombin production is expressed as a percentage of the mean control value for each IgG concentration. Data points and error bars represent the mean and SE of 5 experiments.