Ultrastructure of inclusions in peripheral blood mononuclear cells in sarcoidosis.

Bundle-shaped tubular (BST) inclusions were identified by electron microscopy in 1 to 6 percent of peripheral blood mononuclear cells obtained from 10 to 11 patients with sarcoidosis. The frequency of the inclusions within mononuclear cells did not correlate with the clinical status of the patients. The relationship, if any, of BST inclusions to sarcoidosis and the immunologic defects in sarcoid patients remains to be determined.