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Enhanced cytotoxicity in the rheumatoid joint
E G LaCour1, M H Grayson, C F Ware
1Northwestern University School of Medicine, Department of Medicine, Chicago, Illinois.
Clinical Immunology and Immunopathology
|March 1, 1990
Summary
Tumor necrosis factor-alpha (TNF) is elevated in rheumatoid arthritis synovial fluid, contributing to inflammation and bone destruction. This study found higher cytotoxic activity in rheumatoid arthritis synovial fluid mononuclear cells compared to peripheral blood cells.
Area of Science:
- Immunology
- Rheumatology
- Cytokine Biology
Background:
- Cytotoxic cytokines like tumor necrosis factor-alpha (TNF) and lymphotoxin (LT) mediate bone resorption and inflammation.
- These cytokines may play a role in the pathogenesis of rheumatoid arthritis (RA).
Purpose of the Study:
- To investigate the generation of cytotoxic activity in mononuclear cells (MC) from rheumatoid arthritis patients.
- To compare cytotoxic activity and cytokine production in peripheral blood (PB) and synovial fluid (SF).
Main Methods:
- Isolation of mononuclear cells (MC) from PB and SF of 13 RA patients.
- Assessment of cytotoxic activity using a bioassay for TNF and LT.
- Quantification of TNF using ELISA and neutralization studies with anti-cytokine antibodies.
Main Results:
- Synovial fluid MC exhibited significantly higher spontaneous and phytohemagglutinin P (PHA)-activated cytotoxic activity than PBMC.
- TNF accounted for 43% (PB) and 59% (SF) of PHA plus phorbol-12-myristate acetate (PMA)-induced cytotoxic activity.
- Elevated TNF concentrations in SF correlated with increased cytotoxicity, suggesting its contribution to RA pathogenesis.
Conclusions:
- Increased TNF production in the synovial fluid of RA patients may drive inflammation and bone destruction.
- Further investigation is needed to identify the remaining cytotoxic activity not neutralized by anti-TNF or anti-LT antibodies.