Connective tissue activation XXVI: IgG stimulation of glycosaminoglycan synthesis in human synovial cultures.

Substances known to enhance synthesis of glycosaminoglycans (GAG) in human synovial fibroblast cultures include "Connective Tissue Activating Peptides" (CTAP) isolated from certain organs, leukocytes and platelets as well as cyclic AMP and specific prostaglandins. This report shows that immunoglobulin G (IgG) isolated from 7 mammalian sources, including human, stimulated GAG production by human synovial cultures 3 to 18 fold. IgG generally did not stimulate DNA synthesis by human synovial fibroblasts as determined by [3H]-thymidine uptake. On a molar basis, IgG had a specific activity similar to that of CTAP-Ib(spleen) and CTAP-III (platelets). Normal human plasma levels of IgG may be sufficient to provide additional stimulus for activation of synovial connective tissue during the inflammatory response.