A quantitative test to detect lymphocytes sensitized against the surface of muscle cells.

A test is described which assesses quantitatively the capacity of lymphocytes taken from myositic animals to adhere to skeletal muscle cells in vitro. Lymphocytes were taken from guinea-pigs in which a polymyositis had been induced by injection of rabbit skeletal muscle and complete Freund's adjuvant. These lymphocytes attached themselves preferentially to multinucleate myotubes as opposed to the mononuclear cells in tissue cultures made from chick skeletal muscle. The degree of preference was calculated as a Preferential Attachment (PA) index. This index was high in those animals which developed myositis. In contrast lymphocytes from various groups of control guinea-pigs all gave a PA index of around 1. This test is now being adapted for use in the diagnosis and study of polymyositis in human patients.