Symptoms in patients with lowered levels of IgG subclasses, with or without IgA deficiency, and effects of immunoglobulin prophylaxis.

Several patients with subnormal levels of IgG subclasses have repeated infections. Further controlled studies are required to better define the relation between the level of the various subclasses and the possible clinical consequences. It may be important to determine whether or not IgG subclass deficiency can lead to infections which cause lung damage as was suggested in a few patients with IgA deficiency combined with low IgG subclass levels. An open study of the effect of immunoglobulin prophylaxis in 38 patients with subnormal levels of one or two of the IgG subclasses 1, 2 or 3 during altogether 1,524 months of observation suggested that many of them improved. This must be further substantiated in carefully controlled studies. Immunoglobulin prophylaxis could be given in IgG subclass deficient patients with IgA deficiency and anti-IgA antibodies, provided a preparation poor in IgA was used and the patients' anti-IgA titres did not increase during the prophylaxis.