Abnormal Structures in Circulating Lymphocytes from Patients with Systemic Lupus Erythematosus and Related Diseases

A prospective electron microscopic study, incorporating blind controls, demonstrated tubuloreticular structures (TRS) in the buffy coat lymphocytes of 32 patients with connective tissue disease. From 1 to 8% of the lymphocyte sections were involved. The abnormal structures consisted of interwoven, electron‐dense tubules (220 to 280 Å diameter) which were located within the endoplasmic reticulum. Tubuloreticular structures were found in lymphocytes from 20 of 30 patients with systemic lupus erythematosus (SLE), 2 of 4 with discoid lupus erythematosus, 8 of 20 with other connective tissue disease and none of 22 control cases. Clinical evaluation of the patients with SLE disclosed no specific differences between those with TRS‐positive or TRS‐negative lymphocytes; there were some indications of greater disease activity in the TRS‐positive group. The biologic nature of TRS is unknown, but they have been linked to virus infection under both clinical and experimental conditions.