Intact proteoglycan is a polyclonal activator of murine B-lymphocytes

Destruction of articular cartilage is the hallmark of both inflammatory and degenerative arthritides. Since degradation of cartilage results in the release of proteoglycan (PG) monomers and fragments into the synovial fluid, the present study was initiated to determine whether hyaline cartilage PG can induce a cellular immune response. Nonimmune spleen cells obtained from A/St and C57Bl/6 mice were cultured with a crude extract of bovine nasal cartilage, a PG aggregate fraction, PG monomer or degraded PG monomer for varying time periods. Only intact PG monomer induced a proliferative response which peaked at day 2. The responding cell was a B-lymphocyte which did not require T-helper cell activity. Our results suggest that intact PG monomer is a polyclonal activator of B-lymphocytes.