M. Juan et al., Regulation of ICAM-(3) and other adhesion molecule expressions on eosinophils in vitro. Effects of dexamethasone, ALLERGY, 54(12), 1999, pp. 1293-1298
Background: ICAM-3 has been recently identified as the third leukocyte-func
tion associated-1 (LFA-1) ligand. ICAM-3 is expressed in eosinophils, but i
ts regulation has not been studied. The objective of this study was to inve
stigate the differential expression of ICAM-3 and other adhesion molecules
(AM) on the surface of eosinophils. We also evaluated the effects of dexame
thasone on AM expression.
Methods: Normodense eosinophils were isolated from peripheral blood and inc
ubated with calcium ionophore A23187 (calcimycin) with and without dexameth
asone. Expression of AM was assessed by flow cytometry and expressed as flu
orescence mean intensity (FMI).
Results: Peripheral blood eosinophils constitutively expressed low levels o
f ICAM-1 and ICAM-2 (<10 FMI), moderate levels (10-50 FMI) of CD29 and L-se
lectin, and high levels (>50 FMI) of ICAM-3, LFA-1, and Mac-1. Calcium iono
phore (1 mu M) significantly increased Mac-1 and ICAM-1 expression at 6 and
24 h. L-selectin expression decreased at 6 and 24 h, but ICAM-2, ICAM-3, L
FA-I, and CD29 expression did not show any significant change after calcium
ionophore stimulation. Dexamethasone decreased ICAM-3 and increased L-sele
ctin basal expression, and it caused a dose-related inhibition of calcium i
onophore-induced ICAM-1 expression.
Conclusions: These findings suggest that some AM, such as ICAM-1, Mac-1, an
d L-selectin, may be involved in adhesion during eosinophil activation and
that glucocorticoids may prevent airway inflammation by regulating the expr
ession of AM in eosinophils. The role of ICAM-3, a leukocyte AM highly expr
essed in resting eosinophils, remains to be clarified.