Immunoregulatory activity of peptides related to platelet factor 4.
Platelet factor 4 (PF4), a secreted platelet protein, alleviates concanavalin A-induced immunosuppression in mice. We now find that activity also resides in (i) the C-terminal tridecapeptide of PF4 (P13S), (ii) an analog of this in which arginine replaces the lysine residues and in which the last two amino acids are absent, (iii) the C-terminal 18 amino acids of low-affinity platelet factor 4, which is very similar to P13S, and (iv) peptide fragments of P13S that contain only 5-9 amino acids. P13S treated with fluorescamine to derivatize the free amino groups retained immunoregulatory activity but did not bind to heparin-agarose. The N-terminal and middle portions of PF4, polylysine, protamine, and three unrelated peptides were inactive in this assay.
Zucker
M B
MB
Department of Pathology, New York University Medical Center, NY 10016.
Katz
I R
IR
Thorbecke
G J
GJ
Milot
D C
DC
Holt
J
J
D000595:Amino Acid Sequence; D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D007165:Immunosuppression Therapy; D016403:Lymphoma, Large B-Cell, Diffuse / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology* / Q000494:pharmacology; D010978:Platelet Factor 4 / Q000276:immunology* / Q000494:pharmacology; D011107:Polylysine / Q000494:pharmacology; D011479:Protamines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology
D010446:Peptide Fragments; D011479:Protamines; D011994:Recombinant Proteins; D003208:Concanavalin A; D011107:Polylysine; D010978:Platelet Factor 4