SummaryCytokines such as interleukin 1 (ILl) promote adhesiveness in human umbilical vein endothelial cells for leukocytes including basophils, eosinophils, and neutrophils, and induce expression of adherence molecules including ICAM-1 (intercellular adhesion molecule-1), ELAM-1(endothelialleukocyte adhesion molecule-1), and VCAM-1 (vascular cell adhesion molecule-1) . In the present study, blocking monoclonal antibodies (mAb) recognizing ICAM-1, ELAM-1, and VCAM-1 have been used to compare their roles in 11.,l-induced adhesion of human basophils, eosinophils, and neutrophils. IL-I treatment of endothelial cell monolayers for 4 hours induced a four-to eight-fold increase in adhesion for each cell type. Treatment of endothelial cells with either anti-ICAM-1 or anti-ELAM-1 mAb inhibited IIr1-induced adherence of each cell type. In contrast, treatment with antiVCAM-1 mAb inhibited basophil and eosinophil (but not neutrophil) adhesion, and was especially effective in blocking eosinophil adhesion. The effects of these mAb were at least additive. Indirect immunofluorescence and flow cytometry demonstrated expression of VLA-4cx (very late activation antigen-4cx, a counter-receptor for VCAM-1) on eosinophils and basophils but not on neutrophils . These data document distinct roles for ICAM-1, ELAM-1, and VCAM-1 during basophil, eosinophil, and neutrophil adhesion in vitro, and suggest a novel mechanism for the recruitment of eosinophils and basophils to sites of inflammation in vivo .Acute allergic reactions in the skin and airways are often L .1 followed by a more sustained inflammatory reaction (the so-called late phase response) characterized by the appearance of eosinophils and basophils, as well as neutrophils and mononuclear cells (1) . The fact that increased numbers of eosinophils and basophils appear during these and other mflammatory responses suggests that mechanisms exist which facilitate their activation and recruitment to extravascular sites. Results of studies examining in vitro binding of purified leukocyte subtypes to cultured human vascular endothelial cells have suggested that endothelium can play an active role in the recruitment of leukocytes . The cytokines 11-4 and TNF can stimulate cultured endothelial cells to acquire adhesive properties for various peripheral blood leukocytes in vitro (2-5) . During these treatments, changes in adhesiveness are associated with the induction on endothelial cells of at least three distinct adhesion molecules : ICAM-1, ELAM-1, and VCAM-1, identical to inducible cell adhesion molecule-110 (INCAM-110) and the lE7/2G7 protein (6, 7). Both ELAM-1 and ICAM-1 are important ligands in neutrophil adhesion to activated endothelium (7-10), while VCAM-1 does not appear to participate (11, 12) . Since the endothelial cell adherence receptors for eosinophils and basophils are unknown, we used blocking mAb to ICAM-1, ELAM-1, and VCAM-1 to compare their effects on the adhesion of basophils, eosinophils, and neutrophils to cytokine-activated endothelium in vitro. Materials and M...

Airway epithelium may actively participate in inflammatory responses, such as occur in asthma. The presence and regulation of surface molecules on the airway epithelium, however, is incompletely understood. We have determined the phenotype of the human bronchial epithelial cell line BEAS-2B by flow cytometry. We confirmed previous observations that human bronchial epithelial cells constitutively express CD29, CD44, CD49a, CD49b, CD49c, CD49d, CD49e, CD49f, CD51, CD54 (ICAM-1), CD61, and HLA class 1. BEAS-2B cells were also found to constitutively express CD9, CD13, CD15, CD15s, CD23, CD33, CD36, CD40, CD41b, CD42b, CD48, CD50, CD71, and CD102 (ICAM-2). Culture of BEAS-2B cells with tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta (1 ng/ml) was found to enhance intercellular adhesion molecule-1 (ICAM-1) expression (several fold) and induce de novo CD106 [vascular cell adhesion molecule-1 (VCAM-1)] expression. TNF-alpha or IL-1beta did not change the expression of CD9, CD13, CD16, CD23, CD29, CD31, CD32, CD35, CD45, CD61, or CD64 in BEAS-2B cells. IL-4 (1 ng/ml) also induced expression of VCAM-1 (1.5-fold) but not ICAM- expression while interferon-gamma (1 ng/ml) enhanced only ICAM-1 expression (2-fold). Maximal VCAM-1 expression was obtained with the combination of TNF-alpha and IL-4 (8-fold). Using Northern blot hybridization analysis, ICAM-1 and VCAM-1 mRNA was detected in BEAS-2B cells stimulated with cytokines. VCAM-1 on stimulated BEAS-2B was functionally active as determined by adhesion of purified eosinophils and blockade with specific antibodies. Primary isolates of bronchial epithelial cells produced detectable levels of VCAM-1 protein and mRNA as detected by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction, respectively. These results suggest that cytokine activation induces expression of ICAM-1 and VCAM-1 on airway epithelium, an event which may influence leukocyte infiltration and activation.

The β2 family of integrins, CD11a, CD11b, CD11c, and αd, are expressed on most leukocytes. We show that the newest member of this family, αd, is expressed on human eosinophils in peripheral blood, and surface expression can be upregulated within minutes by phorbol ester or calcium ionophore A23187. Culture of eosinophils with interleukin 5 (IL-5) leads to a two- to fourfold increase in αd levels by 3–7 d without a change in α4 integrin expression. Eosinophils isolated from late phase bronchoalveolar lavage fluids express αd at levels similar to that seen after 3 d of IL-5 culture. Regarding αdβ2 ligands, in both freshly isolated and IL-5–cultured eosinophils, as well as αdβ2-transfected Chinese hamster ovary cells, αdβ2 can function as a ligand for vascular cell adhesion molecule 1 (VCAM-1). This conclusion is based on the ability of monoclonal antibodies to αd, β2, or VCAM-1 to block cell attachment in static adhesion assays. In experiments with eosinophils, the relative contribution of αdβ2 integrin– mediated adhesion is enhanced after IL-5 culture. These experiments demonstrate that αdβ2 is an alternative ligand for VCAM-1, and this integrin may play a role in eosinophil adhesion to VCAM-1 in states of chronic inflammation.

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