lalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetyl- glycerol to induce non-polar motile cells ruffling

Integrins are a widely expressed family of cell-matrix and cell-cell adhesion receptors that also have signalling functions. They are heterodimers consisting of non-covalently linked α and β subunits. There are 8 known β subunits and 14 known α subunits (Hynes, 1987, 1992). Many α subunits can associate with only a single β subunit, but recent results indicate that certain α subunits associate with more than one β subunit (Cheresh et al., 1989; Krissansen et al., 1990; Vogel et al., 1990). The leukocyte-specific β2 integrins (CD18) associated with subunits CD 11a, b, c are still referred to by earlier names: αLβ2 is LFA-1, αMβ2 is MAC1 or CR3 and αXβ2 is p150,95. Expression of CD18-containing integrins is required for normal neutrophil function in vivo. Patients with the clinical syndrome ‘leukocyte adhesion deficiency (LAD)’ suffer from recurrent life-threatening bacterial infections. Their leukocytes do not adhere stably to the endothelium because they lack cell surface expression of all three CD11/CD18 leukocyte integrins due to heterogeneous defects in the β subunit (Larson and Springer, 1990; Harlan et al., 1991). Granulocytes from LAD patients were found to be defective with respect to cell-cell adhesion and other adhesion-dependent functions such as migration in vitro and in vivo, phagocytosis and killing (Harlan et al., 1991; Yong et al., 1991;) and antibody-mediated neutrophil antihuman tumor cytotoxicity (Kushner and Cheung, 1992). Also the acquired pseudo-Pelger granulocyte dysfunction is associated with decreased surface expression of CD11b/CD18 (Mazzone et al., 1990). On the other hand, stimulation of normal neutrophil by phagocytic stimuli, phorbol myristate 493 Journal of Cell Science 106, 493-502 (1993) Printed in Great Britain © The Company of Biologists Limited 1993