Production of mononuclear cell factor by mononuclear phagocytes from rheumatoid synovial fluid

Area of Science:

• Rheumatology
• Immunology
• Cell Biology

Background:

• Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints.
• Synovial fluid macrophages (SF-M phi) are key immune cells implicated in RA pathogenesis.
• Understanding the molecular mediators produced by SF-M phi is crucial for RA research.

Purpose of the Study:

• To investigate the production of collagenase and PGE1-stimulating activities by SF-M phi in rheumatoid arthritis patients.
• To characterize the molecular properties of this activity, termed mononuclear cell factor (MCF).
• To determine if MCF is produced at the local site of inflammation in RA.

Main Methods:

• Culture of synovial fluid macrophages (SF-M phi) from RA patients.
• Analysis of culture supernatants for collagenase and PGE1-stimulating activities.
• Molecular weight estimation of the active factor using established biochemical techniques.

Main Results:

• Culture supernatants from SF-M phi of RA patients exhibited significant collagenase and PGE1-stimulating activities.
• This activity, identified as mononuclear cell factor (MCF), was consistently detected in all tested SF-M phi supernatants.
• The apparent molecular weight of MCF was determined to be between 15,000-20,000 daltons, comparable to interleukin-1.
• Evidence suggests MCF is produced by monocyte-macrophages at the local site of joint lesions in RA.

Conclusions:

• Monocyte-macrophages in the synovial fluid of RA patients are a source of mononuclear cell factor (MCF).
• MCF possesses collagenase and PGE1-stimulating properties, potentially contributing to joint destruction in RA.
• The findings highlight the role of local cellular factors in the inflammatory process of rheumatoid arthritis.