Interactions between cells of the immune system and hyaluronate synthesis by human dermal fibroblasts

Mitogen- or alloantigen-activated human peripheral blood mononuclear cells (MNC) produce a soluble factor which selectively stimulates up to twenty-fold the synthesis of glycosaminoglycan (GAG) by cultured normal human fibroblasts. Confluent fibroblast monolayers were incubated with active MNC supernatants and newly synthesized GAG was measured by the incorporation of [3H]glucosamine into cetylpyridinium chloride-precipitable material. The GAG-stimulatory factor (GAG-SF) was a product of T lymphocytes. Alloreactive T cell clones obtained from the peripheral blood produced the factor after reactivation with the irradiated stimulators, and its production was dependent on HLA-DR-mediated recognition. The CD3+CD4+ clones derived from the skin-infiltrating lymphocytes in patients with early scleroderma also produced the GAG-SF upon in vitro activation with a mitogen. The GAG-SF was purified to apparent homogeneity from supernatants of concanavalin A-activated MNC by Sephadex gel filtration, ion-exchange chromatography and reverse-phase HPLC. The GAG-SF is a 67,000 Da glycoprotein with pI of 5.6. It is not mitogenic to fibroblasts and does not modulate collagen synthesis. Its purification and characterization are important, because of a possible involvement of activated lymphocytes and their products in the immunopathogenesis of human diseases characterized by fibrosis, stromal reactions and local lymphocytic infiltrates.