EFFECT OF DEXAMETHASONE ON EXPRESSION OF ADHESION MOLECULES ON CD4(+)LYMPHOCYTES

Despite the widespread use of corticosteroids in asthma therapy, littl e is known of the effects of corticosteroids on cell surface markers i nvolved in T lymphocyte activation and adhesion. We used flow cytometr y to analyze the effects of 1, 10, and 100 nM dexamethasone on express ion of markers on resting and phytohemagglutinin (PHA)-stimulated peri pheral blood CD4(+) T lymphocytes. Expression of the leukocyte common antigen CD45 was significantly (P = 0.016, n = 3) increased from an av erage mean fluorescence intensity of 215.8 [95% confidence intervals ( CI): 100.5, 463.5] on cells from unstimulated cultures to 334.2 (CI: 1 67.9, 663.7) on cells from PHA-stimulated cultures after 70-h incubati on. At the same time, the percentage of cells also expressing the CD45 RO isoform, a marker of memory T lymphocytes, increased significantly (P = 0.0006, n = 3) from 54.4 +/- 1.3% (unstimulated) to 92.8 +/- 0.6% (stimulated). Dexamethasone had no significant effect on expression o f CD45 or CD45RO, including the observed changes. Dexamethasone also d id not affect expression of the beta(1)-integrin VLA-4. These results suggest that corticosteroids do not modulate the cell surface expressi on of these molecules involved in CD4(+) T lymphocyte activation, adhe sion, and recirculation.