Steroid-Treated Asthmatic Patients with Low Levels of IgG Have a Normal Capacity to Produce Specific Antibodies

Oral corticosteroids are known to decrease levels of IgG in serum of patients with asthma. The purpose of this study was to determine prospectively if asthmatics with levels of IgG below the normal range have a deficiency in the capacity to respond to several types of antigens. Three groups of patients were examined: steroid-treated asthmatics who had low levels of IgG, steroid-treated asthmatics who had normal levels of IgG, and asthmatics who had never been treated with steroids. All had levels of specific antibodies measured prior, 2 weeks, and 3 months after immunization to tetanus toxoid, Pneumovax, and influenza vaccine. Levels of specific antibody to the five antigens were not different in the three groups. Each group responded to each antigen, and the final antibody titers and the differences between postimmunization and preimmunization titers were not significantly different in the three groups. For all three groups of patients, IgG was the predominant class of antibody responding to the tetanus immunization. The decay rates of the antibody responses from the presumed peak at the 2 weeks to the value at 3 months postimmunization in the three groups were not significantly different. Our results suggest that low levels of total IgG due to steroid therapy in patients with asthma do not necessarily indicate that there is a problem with specific immunity to infectious agents.