A peptide derived from neutrophil inhibitory factor (NIF) blocks neutrophil adherence to endothelial cells.
OBJECTIVE
Peptides derived from neutrophil inhibitory factor (NIF), a known antagonist of Mac-1, were evaluated as inhibitors of neutrophil adherence.


METHODS
In vitro assays of adherence employed: 1) human polymorphonuclear cells (PMN), 2) human umbilical vein endothelial cells (HUVEC), and 3) CHO cells expressing ICAM-1 (CHO-ICAM cells).


METHODS
Cells, pretreated with NIF-derived peptides (0.1-100 microM) for 10 minutes, were permitted to adhere for 20 min in the continued presence of peptide.


METHODS
Cell-based assays: 1) PMN adherence to HUVEC, 2) PMN adhesion to immobilized human serum proteins, and 3) adherence of CHO-ICAM cells to immobilized Mac-1.


RESULTS
A NIF-derived peptide of 29 amino acids blocked PMN adherence to HUVEC, but behaved somewhat differently than the parent NIF protein. NIF specifically antagonized Mac-1 dependent adherence, but the peptide blocked neutrophil adherence that was dependent upon both Mac-1 and LFA-1 integrins. CHO-ICAM adherence to Mac-1 was blocked by NIF, but not by the peptide. Binding studies with NIF and the peptide indicate that the molecules bind to different sites.


CONCLUSIONS
A peptide derived from NIF blocks PMN adherence but, unlike NIF, the mechanism of action is not mediated by direct antagonism Mac-1.
Madden
K
K
Scios Inc., Sunnyvale, CA 94086, USA.
Janczak
J
J
McEnroe
G
G
Lim
D
D
Hartman
T
T
Liu
D
D
Stanton
L
L
D000595:Amino Acid Sequence; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology*; D006023:Glycoproteins / Q000494:pharmacology*; D015801:Helminth Proteins / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013329:Structure-Activity Relationship
D006023:Glycoproteins; D015801:Helminth Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; C086581:NIF protein, Ancylostoma caninum