Objectives: To develop and evaluate a new immunohistochemical method to study the localisation and phenotype of individual cytokine producing cells in synovial biopsy specimens in rheumatoid arthritis.
Methods: Cryopreserved sections of synovial tissue from nine patients with rheumatoid arthritis were incubated with carefully selected cytokine specific antibodies detecting 19 different cytokines, after fixation of the specimens with paraformaldehyde and using saponin to permeabilise the cell membranes.
Results: The immunohistochemical method yielded reproducible and distinct staining patterns, in which the cytokines accumulated mainly in the Golgi apparatus of producer cells, indicating that the method preferentially detected local synthesis rather than cytokine uptake. The cytokine production patterns varied considerably between biopsy specimens from different patients.
Conclusion: The present modified immunohistochemical method may provide a simple and rapid way to determine the local production of a wide array of cytokines in the synovium. The data obtained with this method also indicated that more T cell derived cytokines than previously recognised were present in active synovitis, as located and sampled by arthroscopy.