The invention describes antagonists for PDGF.

CHRF-288-11 cells express platelet peroxidase, platelet factor IV, platelet CA++-ATPase, gpIIbIIIa, factor VIII, and MY7, MY9 and HLA-Dr antigens.

The subject invention pertains to the use of modified PF4 to inhibit angiogenesis.

A particularly preferred cationic protein is purified Platelet Factor 4.

Dimerization is necessary for PDGF effect, hence the antagonistic effect.

The subject invention pertains compositions and methods for treatment of angiogenesis using PF4 and peptide fragments thereof.

The invention features the use of platelet factor 4 (PF4) for inhibiting proliferation of osteoblasts in a mammal in need of such inhibition.

Its activated form, IXa, forms a complex with factor VIII and calcium on platelet factor 3 to activate factor X to Xa.

The compounds useful in such methods bind to a PF4 tetramer, dimer, or monomer.

Especially preferred are dimers which bind the PDGF receptors, but prevent dimerization of the bound receptors.

The pertinent antibodies recognize two epitopes formed by heparin binding to platelet factor 4.

The figure sets forth amino acid sequences for peptides eluted from PDGF-A HPLC experiments.

The monokines are implicated in immunological and inflammatory processes, as are other members of the platelet factor 4 family of cytokines.

Anti-angiogenic substances envisaged in this invention include Angiostatin.RTM., Endostatin.RTM., platelet factor-4, TNP-470, thalidomide, interleukin-12 and metalloproteinase inhibitors (MMP).

The present invention provides a novel assay for detecting human antibodies specific for a platelet factor 4 (PF4)/heparin complex in a fluid sample.