Immunohistochemical localization of somatostatin receptor sst(2A) in humanrheumatoid synovium

Objective. To identify the somatostatin receptor-expressing cells in rheuma toid synovium using a recently developed antiserum directed against the som atostatin receptor subtype 2A (sst(2A)). Methods. We carried out immunohistochemical studies of synovial biopsies fr om 7 patients with rheumatoid arthritis (RA) and one non-RA patient, using a rabbit polyclonal antiserum directed against sst(2A) and monoclonal antib odies directed against phenotypic markers. Results, sst(2A) was expressed by the endothelial cells of the synovial ven ules but also by a subset of synovial macrophages. Conclusion. The identification of somatostatin receptors on macrophages, wh ich are thought to be important effector cells in RA, may offer mechanistic insights into the potential therapeutic effect of somatostatin (analogs) i n RA.