title: Particles with properties of retroviruses in monocytes from patients with breast cancer.
abstract: An agent with the properties of a retrovirus has been detected regularly in monocytes from patients with breast cancer. In 97% of breast cancer patients the cell-free culture medium (CFCM) in which the monocytes had been cultured possessed reverse transcriptase (RT) activity. In contrast, RT activity was detected in the CFCM from only 11% of age and sex matched controls (p less than 0.0001; Wilcoxon rank sum test). The RT activity was associated with particles having a buoyant density of between 1.165 and 1.18 g/ml, similar to that of retroviruses. Treatment of the samples with non-ionic detergent abolished the peaking of the activity in this fraction. Enveloped particles (100-120 nm in diameter) with a fringed surface resembling murine mammary tumour virus were found on negative-stain electron microscopy in CFCM obtained from patients with breast cancer. Retrovirus-like particles were also observed in the cytoplasm of giant cells formed by monocytes from these patients, and also in macrophages in breast cancer tissue; however, no such particles were detected in the tumour cells. These findings strongly suggest the presence of a retrovirus in the monocytes from patients with breast cancer. The importance of these observations in the pathophysiology of carcinoma of the breast remains to be established.
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology / Q000382:microbiology* / Q000648:ultrastructure; D002474:Cell-Free System; D003470:Culture Media; D005260:Female; D006801:Humans; D009000:Monocytes / Q000382:microbiology* / Q000648:ultrastructure; D012194:RNA-Directed DNA Polymerase / Q000032:analysis; D012190:Retroviridae / Q000302:isolation & purification* / Q000648:ultrastructure
chemical_list: D003470:Culture Media; D012194:RNA-Directed DNA Polymerase