CD11/CD18-independent neutrophil adherence to inducible endothelial-leucocyte adhesion molecules (E-LAM) in vitro.
We examined the mechanisms involved in neutrophil adherence to cultured human umbilical vein endothelial cells (HEC) induced by direct stimulation of the neutrophils by phorbol myristate acetate (PMA), formylmethionyl-leucyl-phenylalanine (FMLP), or the calcium ionophore A23187 (neutrophil-dependent adherence), or by pretreatment of HEC with interleukin-1 (IL-1), tumour necrosis factor (TNF) or lipopolysaccharide (LPS) (endothelial-dependent adherence). Two distinct mechanisms for neutrophil adherence to HEC were demonstrated by performing adherence assays: (i) at 37 degrees versus 4 degrees; (ii) in the presence of Ca2+ only versus Mg2+ only; and (iii) in the presence or absence of monoclonal antibodies (mAb) to the CD11/CD18 adhesion complex of neutrophils. A CD11/CD18-dependent mechanism (i.e. inhibited by anti-CD18 mAb) was identified that was active in the presence of Mg2+ only but not of Ca2+ only, and at 37 degrees but not at 4 degrees. A CD11/CD18-independent mechanism (i.e. not inhibited by anti-CD18 mAb) was active at 4 degrees and at 37 degrees, and in the presence of Ca2+ only and of Mg2+ only. Neutrophil-dependent adherence induced by FMLP or PMA occurred solely via the CD11/CD18-dependent mechanism, whereas endothelial-dependent adherence induced by a 4-hr pretreatment with IL-1, TNF, or LPS involved both CD11/CD18-dependent and/independent mechanisms. CD11/CD18-deficient neutrophils isolated from a patient with leucocyte adherence deficiency (LAD) maintained the ability to adhere to LPS-pretreated HEC in the presence of Ca2+ only, indicating that this mechanism of adherence involves a receptor on the neutrophil distinct from CD11/CD18. Furthermore, the disappearance of the CD11/CD18-independent, but not of the CD11/CD18-dependent mechanism of adherence, in HEC treated with TNF for 24 hr suggests that the two mechanisms of neutrophil adherence also involve distinct inducible endothelial-leucocyte adhesion molecules (E-LAM).
Dobrina
A
A
Institute of General Pathology, University of Trieste, Italy.
Schwartz
B R
BR
Carlos
T M
TM
Ochs
H D
HD
Beatty
P G
PG
Harlan
J M
JM
D000954:Antigens, Surface / Q000276:immunology; D018821:CD18 Antigens; D002118:Calcium / Q000502:physiology; D002448:Cell Adhesion; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000276:immunology*; D006801:Humans; D008274:Magnesium / Q000502:physiology; D008562:Membrane Glycoproteins / Q000502:physiology*; D009504:Neutrophils / Q000502:physiology*
D000954:Antigens, Surface; D018821:CD18 Antigens; D008562:Membrane Glycoproteins; D008274:Magnesium; D002118:Calcium