Connective Tissue Activation XVI. Detection of a Human Platelet-Derived Connective Tissue Activating Peptide (CTAP-III) in Human Sera and Plasma and in Synovial Fluids and Tissues

Abstract

Antisera were prepared to the platelet-derived connective tissue activating peptide (CTAP-III) and used to ascertain the presence of CTAP-III materials in a number of biologic specimens by double immunodiffusion analyses. Materials reactive with anti-CTAP-III sera were found in all human sera and platelet extracts tested; weak reactivities were obtained in human plasma specimens but no reactivity was seen in plasma samples for which care was taken to avoid platelet activation. Extracts of synovial fluids and tissues and a spleen extract, processed in the manner similar to the CTAP-III purification scheme from platelet extracts, exhibited positive reactivities. However, synovial fluids contained no detectable reactivity by the double immunodiffusion method. The anti-CTAP-III sera were not reactive with the many polypeptide hormones and growth factors tested, including the CTAP-I and -II factors and platelet factor-4. Previous studies had shown that CTAP-III, β-thromboglobulin, and the low affinity platelet factor-4 share similar or identical antigenic determinatants. CTAP-III has mitogenic activity for many strains of human connective tissue derived cells and the presence of CTAP-III reactive components in synovial tissues suggests that CTAP-III may in part contribute to the proliferative response of those tissues during inflammation.