Effect of serum amyloid A on selected in vitro functions of isolated human neutrophils.
Serum amyloid A (SAA) is an acute phase reactant whose levels in the blood rise as part of the body's response to stress and inflammation. Previous studies have suggested that SAA may carry an anti-inflammatory potential. We evaluated the effects of SAA on human neutrophils activated by N-formyl-methionyl-leucyl-phenylalanine (fMLP) in vitro. At concentrations higher than 10 microg/mL, SAA inhibited neutrophil myeloperoxidase (MPO) release. This effect was located in the N-terminal--that is, amino acid residues 1-14--of the SAA molecule. Directed neutrophil migration was inhibited at the same SAA concentrations. Several amino acid residues (1-14, 15-104, 83-104) contributed to this effect. Neutrophil O2- production was inhibited at low concentrations of SAA (0.1 to 1 microg/ml) and was stimulated at concentrations higher than 50 microg/mL. Neutrophil O2- production induced by phorbol myristate acetate (PMA) and O2- generated by the xanthine-xanthine oxidase reaction were not affected by SAA. These results add to previous data suggesting that SAA, at concentrations recorded in the serum during inflammation, modulates neutrophil function; thus it may play a role in the down-regulation of the inflammatory process.
Gatt
M E
ME
Hematology Unit, Hadassah University Hospital, Mount Scopus, Jerusalem, Israel.
Urieli-Shoval
S
S
Preciado-Patt
L
L
Fridkin
M
M
Calco
S
S
Azar
Y
Y
Matzner
Y
Y
D000328:Adult; D015550:Cell Degranulation / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D018375:Neutrophil Activation / Q000187:drug effects; D009504:Neutrophils / Q000502:physiology*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D009195:Peroxidase / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D000685:Serum Amyloid A Protein / Q000031:analogs & derivatives / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism
D010446:Peptide Fragments; D011994:Recombinant Proteins; D000685:Serum Amyloid A Protein; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009195:Peroxidase