Tubuloreticular structures and cylindrical confronting cisternae: a review

Tubuloreticular structures (TRS) and cylindrical confronting cisternae (CCC) are unique subcellular structures that arise from the membranes of the rough endoplasmic reticulum of a variety of cell types. In vivo, they occur most frequently in endothelial cells and lymphocytes from patients with autoimmune diseases and viral infections; they are seen in these cells in almost all acquired immunodeficiency syndrome (AIDS) patients. The inducer(s) of TRS and CCC in vivo is (are) not firmly established. However, clinical and experimental studies indicate that the occurrence of these structures in these diseases is directly related to the endogenous elevation of alpha- and beta-interferon but not to gamma-interferon. Although CCC have been seen and reported to occur in human and primate cells since the late 1970s, their presence did not arouse much clinical and scientific interest until 1983 when they were observed in lymph node tissues of AIDS patients. The nature and pathogenesis of TRS and CCC are obscure. Through the years, many hypotheses have been proposed. They range from suggestions of these structures being incomplete viral particles to being nothing more than accumulated proteins; and from reference to these structures as specific markers for diseases to a generalized cell reaction to certain biological stimuli. In vitro investigations with lymphoblastoid cell lines have contributed a great deal in illuminating the potential clinical significance and the in vivo inducer(s) of TRS and CCC. Both the TRS and CCC are now known to be induced in vitro by alpha- and beta-interferon in some lymphoblastoid cell lines. However, only TRS and not CCC are induced in healthy donor lymphocytes and endothelial cells. Isolation of TRS and CCC using the lymphoblastoid cell system will help clarify the nature, the pathogenesis, and the importance of TRS and CCC in human diseases.