Immunoglobulin G of restricted electrophoretic mobility in certain human sera.

Immunoelectrophoretic analysis of certain human sera revealed a deficiency of the fast migrating part of IgG. Sera studied were from individuals suspected of antibody deficiency. Deficiency of fast IgG was especially frequent in children in the second 6 months of life, but was not uncommon up to the age of 5 years. It was found in two adults. This deficiency was not related to serum IgG concentration. A second type of selective deficiency was noted in sera of IgG content of 200 mg/100 ml or less. Analysis of some of these sera, after concentration by ultrafiltration, showed an isolated deficiency of slow migrating IgG. The significance of these findings in relation to subclasses of IgG is discussed.