SERUM IGG SUBCLASSES IN CHRONIC AND RECURRENT RESPIRATORY-INFECTIONS

Abstract

Serum IgG subclasses and IgG, IgA and IgM were measured in 47 patients with chronic respiratory tract infection, 53 patients with recurrent acute respiratory infections and 66 healthy normal adults. Compared to the healthy control group, mean serum IgG2 was significantly lower in patients with chronic infection (P < 0.01) and in those with recurrent infection (P < 0.001); mean serum IgG3 was significantly higher (P < 0.001 for those with chronic and P < 0.05 for those with recurrent infection). Five patients with recurrent infection and 2 with chronic infection had serum IgG2 concentrations > 3 SD below the geometric mean of the control group, and 3 of these had concomitant IgA deficiency (< 0.01 g/1). IgG4 was undetectable in 5 patients with recurrent and 4 with chronic infection, 2 of these also had IgG2 deficiency. In 13 of the 14 patients with IgG subclass deficiencies, total IgG was within the normal range. Selective IgA deficiency with normal IgG subclasses was found in 5 patients. Twenty-seven patients had raised levels of .gtoreq. 1 Ig classes or subclasses. It appears to be important to screen patients with chronic or recurrent respiratory infection for IgG subclass deficiencies in view of the reported beneficial response to .gamma.-globulin therapy.