Selective suppression of IgG2a subclass in LEC rats during development.

The LEC rat is a mutant strain that has been established as a model of hepatitis and hepatoma. In addition to hepatic disorders, it has been found that this strain has a defect in T cell maturation, and has low levels of serum IgG. Sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analysis showed that low levels of serum IgG were largely due to reduction of the IgG2a subclass. Quantitative determination of IgG subclasses by enzyme-linked immunosorbent assay (ELISA) using subclass-specific antibodies indicated that IgG2b and IgG2c subclasses were increased during development in this strain, whereas the IgG2a subclass was markedly decreased. These results suggest that dysfunction of some helper T cells in LEC rats selectively suppress synthesis of the IgG2a subclass during development but not affect production of IgG2b and IgG2c.