COMPARISON OF HUMAN EOSINOPHIL AND NEUTROPHIL ADHESION TO ENDOTHELIAL-CELLS UNDER NONSTATIC CONDITIONS - ROLE OF L-SELECTIN

To simulate adhesion that occurs under conditions of flow, we investig ated the attachment of eosinophils to endothelium under rotational con ditions. Tissue-culture plates containing monolayers of HUVEC were pla ced on a horizontal rotator (80 revolutions per minute (rpm)), and equ al numbers of purified human eosinophils or neutrophils were added to separate wells at 4 degrees C. Binding of eosinophils and neutrophils to unstimulated endothelial cells was 15 +/- 3 and 31 +/- 11 cells/fou r high power fields (HPF), respectively. After preincubation of HUVEC with IL-1 beta (1 ng/ml, 4 h, 37 degrees C), adhesion increased to 56 +/- 4 and 290 +/- 26 cells/four HPF, respectively (p < 0.0002 for both , n = 8-14). Eosinophils with reduced levels of L-selectin (blood eosi nophils activated in vitro or eosinophils obtained from bronchoalveola r ravage (BAL) performed after segmental lung allergen challenge of al lergic subjects) demonstrated reduced binding under rotating condition s. Several L-selectin Abs inhibited adhesion of eosinophils and neutro phils (e.g., LAM1-3: 43 +/- 14% vs 63 +/- 3% inhibition; LAM1-6: 73 +/ - 5% vs 36 +/- 6% inhibition, respectively, n greater than or equal to 6). Interestingly, one additional L-selectin Ab, LAM1-11, inhibited e osinophil but not neutrophil adhesion (51 +/- 2% vs 1 +/- 7% inhibitio n, respectively, n greater than or equal to 5). We conclude that eosin ophils like neutrophils, use L-selectin to bind to activated endotheli al cells under conditions of flow, although mAb LAM1-11 can selectivel y inhibit eosinophil attachment to stimulated endothelial cells in vit ro, suggesting different functional epitopes on L-selectin among eosin ophils and neutrophils.