STEROID-RESISTANT ASTHMA IMMUNOLOGICAL CHARACTERISTICS

'Objective. To investigate whether persistent T lymphocyte activation is a feature of steroid-resistant (SR) asthma and to study the inhibit ory effects of dexamethasone and other immune-inhibiting agents on PHA -induced proliferation of peripheral blood T lymphocytes from SR and s teroid-sensitive (SS) asthmatics. Material and Methods. 15 SR and 15 S S asthmatics were studied. Serum levels of soluble interleukin-2 recep tor (sIL-2R) were measured before and after prednisone therapy by an e nzyme-linked immunosorbent assay. PHA-driven proliferative assay was p erformed to evaluate inhibition of T lymphocyte proliferation. Results . Serum levels of sIL-2R were elevated in both patients with SR and SS asthma as compared with normal controls (P<0.001). After a 7-day cour se of prednisone (20mg / day), serum levels of sIL-2R decreased signif icantly in SS asthmatics (P<0.001) but not in SR asthmatics (P>0.1). P roliferation of T lymphocytes from the sensitive but not the resistant asthmatics was significantly (P<0.002) inhibited by dexamethasone (10 mol / L), reflecting a shift of the dose-response curve. In contrast, oxymatrine and thymus-derived immunosuppressors inhibited proliferati on of T lymphocytes to a similar degree between SR and SS asthmatics. Conclusions. The results suggest that persistent T Lymphocyte activati on due to a relative insensitivity of the cells to glucocorticoids is a feature of SR asthma. Immuno-inhibiting agents other than glucocorti coids may be of therapeutic benefit in patients with SR asthma.