Steroid-resistant asthma immunologic characteristics.
OBJECTIVE
To investigate whether persistent T lymphocyte activation is a feature of steroid-resistant (SR) asthma and to study the inhibitory effects of dexamethasone and other immuno-inhibiting agents on PHA-induced proliferation of peripheral blood T lymphocytes from SR and steroid-sensitive (SS) asthmatics.


METHODS
15 SR and 15 SS asthmatics were studied. Serum levels of soluble interleukin-2 receptor (sIL-2R) were measured before and after prednisone therapy by an enzyme-linked immunosorbent assay. PHA-driven proliferative assay was performed 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 course of prednisone (20 mg/day), serum levels of sIL-2R decreased significantly in SS asthmatics (P < 0.001) but not in SR asthmatics (P > 0.1). Proliferation 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 proliferation of T lymphocytes to a similar degree between SR and SS asthmatics.


CONCLUSIONS
The results suggest that persistent T lymphocyte activation due to a relative insensitivity of the cells to glucocorticoids is a feature of SR asthma. Immuno-inhibiting agents other than glucocorticoids may be of therapeutic benefit in patients with SR asthma.
Sun
Y
Y
Department of Respiratory Medicine, Peking Union Medical College Hospital, Beijing.
Luo
W
W
D000328:Adult; D001249:Asthma / Q000188:drug therapy* / Q000276:immunology; D003907:Dexamethasone; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D011241:Prednisone / Q000627:therapeutic use*; D015375:Receptors, Interleukin-2 / Q000097:blood*; D013601:T-Lymphocytes / Q000276:immunology*
D015375:Receptors, Interleukin-2; D003907:Dexamethasone; D011241:Prednisone