Subclass restriction of immunoglobulin G in liver cirrhosis.

The serum immunoglobulin G (IgG) subclasses were determined in 41 patients with liver cirrhosis (LC) and in 15 normal controls. In 19 cases of LC and in 6 normal controls, the IgG subclasses were also determined in lymphocyte culture supernatants. The determinations were performed by enzyme immunoassay. It was found that the absolute mean IgG1 and IgG3 levels were increased in all LC due to various causes. The mean IgG1 increase was most pronounced in post-hepatitic LC, and the mean percentage of IgG1 to total IgG was also increased in this type of LC in comparison with the normal controls and the other types of LC. The IgG3 fraction was significantly increased in primary biliary cirrhosis (PBC). In alcoholic LC, all IgG subclasses were increased significantly in comparison with normal controls. In lymphocyte culture supernatants from PBC patients, the mean IgG1 and IgG3 levels were increased in supernatants from unstimulated cultures, and the mean IgG1, IgG3, and IgG4 were increased after pokeweed mitogen (PWM) stimulation. In post-hepatitic LC, the mean IgG4 level was increased in both unstimulated culture supernatants and after PWM stimulation. In alcoholic LC, the mean IgG4 level was increased in unstimulated culture supernatants, whereas the mean IgG1 level was increased after PWM stimulation. These findings showed that LC of differing aetiologies exhibited different profiles of IgG subclasses. This may be related to the different aetiological agents and the pathogenesis of the different types of LC.