Mononuclear cells recovered from inflammatory synovial membrane using fine-needle biopsy

A simple technique for fine-needle aspiration biopsy from the synovial membrane of arthritis knee joints preceded by lavage of the joint cavity is described. The procedure was atraumatic, well accepted, and could be performed on outpatients. Cells originating from the synovial membrane were obtained in 12 of 17 knees using a 1.2-mm cannula. The yield was 6.0×10³ to 135×10³ mononuclear cells. The cell populations could be expanded by stimulation with antigen and mitogen. The described fine-needle biopsy technique is of value when repeated sampling of synovial membrane cell populations is desired.