ABSTRACT
The therapeutic effect and mechanism of action of immunoglobulin G (IgG) on bronchial asthma are not defined. Recently, it has been proposed that mononuclear cell (MNC) infiltration in the airway plays a role in the pathogenesis of asthma. In this study, we evaluated the effect of IgG on the cell receptor expression and cytokine production of MNC from two groups (young atopic and old non-atopic) of stable asthmatic patients. MNCs from both asthmatic patients and normal healthy individuals were obtained after Ficoll-Hypaque separation. Cells were cultured in serum free AIM-V medium, with or without phytohemagglutinin (PHA, 5 micrograms/ml) and IgG (100 micrograms/ml). After culture, MNCs were harvested and stained with monoclonal antibodies for HLA-DR (Ia), CD23 and CD3. MNC supernatants were collected for IL-2 and IL-4 measurement. The results showed an enhancing effect of IgG on young atopic MNC proliferation when stimulated with PHA. The production of IL-2 and IL-4 from MNCs were significantly higher in old non-atopic asthmatics after PHA stimulation. The CD23, but not HLA-DR, expression on CD3 positive T cells and cytokines (IL-2 and IL-4) production were increased by IgG when stimulated with PHA in young atopic asthmatics. To the contrary, the effect of IgG on PHA stimulated MNC proliferation, CD23 and HLA-DR expression on CD23 positive T cells in old non-atopic asthmatics were trivial. Only IL-4 production can be significantly inhibited by IgG. These results suggested that the therapeutic effect of IgG on asthmatics might be variable in different groups of asthmatics.(ABSTRACT TRUNCATED AT 250 WORDS)