Differential effects of inhaled budesonide and oral prednisolone on serum immunoglobulin G and its subclasses in healthy adult volunteers

Background Glucocorticosteroid (GCS) treatment lowers serum IgG and IgG subclass (IgG-SC) levels, but the minimal dose and duration of administration at which this occurs is not known. Objective The aim of this study was to define the daily dose of a 2-week course of GCS at which IgG(-SC) suppression occurs. Methods The effects of three GCS treatment schemes on serum IgG(-SC) levels in healthy adults were studied in a double-blind, randomized trial. Group I (n= 10) was treated with 40mg oral prednisolone/day, group 2 (n= 10) with 10 mg oral prednisolone/day and group 3 (n= 10) with 3.2 mg inhaled budesonide/day. Blood sampling was performed at baseline and at the end of the 2-week treatment period. Results In group 1, IgGl, IgG2 and lgG3 levels were significantly decreased after treatment, while in group 2 this was only so for IgG3. In both groups, the decrease of total IgG tended towards or just reached significance. In group 3, no statistically significant changes were observed. Conclusion A course of 40mg oral prednisolone/day for 2 weeks induces significant suppression of serum IgG-SC levels; lower doses cause more subtle changes, indicating that GCS-induced IgG-SC suppression is a dose-dependent phenomenon. Short courses of very high doses of inhaled budesonide appear to be devoid of this side-effect.