IgG - subclass abnormalities in primary immunodeficiency diseases.

IgG-subclass levels were determined in the sera of 45 patients suffering from various types of immunodeficiency disease. Imbalances of IgG-subclass concentrations were found in 25 cases. IgG-4 levels were most frequently more depressed than the levels of the other subclasses. The percentage distribution of IgG-subclasses was normal in the remaining 20 sera. In a patient with autosomal recessive alymphocytic agammaglobulinemia, subclass concentrations drastically increased after bone marrow transplantion showing transient peaks of restricted heterogeneity. Normal IgG-subclass levels were reached at the end of the observation period.