REGULATION OF CELL-ADHESION MOLECULE EXPRESSION AND FUNCTION-ASSOCIATED WITH NEUTROPHIL APOPTOSIS

We have investigated the adhesive capacity of neutrophils after sponta neous apoptosis, which occurs during in vitro culture. Apoptotic neutr ophils show reduced adhesion to E selectin and the CD18 integrin ligan d fibrinogen. Neutrophil apoptosis is associated with changes in the l evels of surface expression of key receptors that mediate neutrophil a dhesion events, Notably, apoptotic neutrophils show reduced expression of L-selectin/selectin ligand, In contrast, CD11b/CD18 and CD11c/CD18 integrins are expressed at increased levels, The reduced capacity for adhesion of apoptotic neutrophils may be achieved by very different m echanisms, pegulation of the levels of surface expression of receptors /ligand may control selectin-mediated adhesion, possibly as a result o f protease/sialidase activity, In contrast, modulation of integrin-med iated adhesion may involve functional uncoupling of receptors present on the surface of the apoptotic cell without alteration in levels of s urface expression. The altered adhesive potential of the apoptotic neu trophil may serve to limit release of its histotoxic contents and redu ce inappropriate tissue injury. (C) 1995 by The American Society of He matology.