Classification of smooth muscle autoantibodies detected by immunofluorescence

Abstract

Three hundred and twelve sera containing antibodies to smooth muscle (SMA) wer analysed for the immunofluorescence patterns they produced in various tissues. A classification is described based on the three main appearances in rat kidney. Some sera, mainly of low titre, reacted only with vessel walls (SMA-V), some stained vessels and renal glomeruli (SMA-G) and high titre sera, mainly from patients with chronic active hepatitis stained vessels, glomeruli, and intracellular fibrils in renal tubules (SMA-T). Peripheral staining in hepatocytes or thyroid cells was not a regular feature. 41/43 polyclonal SMA-T and -G sera were absorbed out completely by actin, and this also removed the pericullular staining in liver and thyroid when present. High titre SMA-V antibodies could not be absorbed by actin, and the antigen remains to be identified.