Synovial fluid mononuclear cells exhibit a spontaneous HLA-DR driven proliferative response

Area of Science:

• Immunology
• Rheumatology
• Cell Biology

Background:

• Synovial fluid mononuclear cells (SFMC) spontaneously proliferate in vitro.
• This proliferation is observed in patients with rheumatoid arthritis (RA) and seronegative spondyloarthropathies (SN).
• The underlying mechanism of SFMC proliferation is not fully understood.

Purpose of the Study:

• To test the hypothesis that SFMC proliferation is analogous to the autologous mixed lymphocyte reaction (AMLR).
• To investigate the role of T cells, HLA-DR, and interleukin-2 (IL-2) in SFMC spontaneous proliferation.
• To explore the implications for antigen-presenting cell/T cell interactions in inflammatory joint diseases.

Main Methods:

• Studied the effects of cyclosporin A, anti-HLA-DR antibody, and recombinant IL-2 (rIL-2) on SFMC proliferation.
• Utilized SFMC from patients with RA and various SN.
• Analyzed the impact of these agents on spontaneous SFMC proliferation in vitro.

Main Results:

• SFMC proliferation is a T cell-mediated response.
• Cyclosporin A and anti-HLA-DR antibody inhibited SFMC proliferation.
• rIL-2 enhanced SFMC proliferation, an effect blocked by anti-HLA-DR antibody.
• These findings indicate an HLA-DR driven, IL-2 dependent mechanism analogous to AMLR.

Conclusions:

• Spontaneous SFMC proliferation in inflammatory joint diseases is partly an HLA-DR driven, IL-2 dependent event.
• This phenomenon resembles the autologous mixed lymphocyte reaction (AMLR).
• Supports the role of antigen-presenting cell/T cell interactions in the synovial membrane in RA and related conditions.