Urine pellet material of patients with leukemia was examined by electron microscopy in an effort to find more convenient sources of virus material for tissue culture and animal infectivity studies. Thirty urine specimens from 16 patients with acute leukemia, 2 patients with chronic granulocytic leukemia and 1 patient with Burkitt’s lymphoma, and 17 urine samples from 15 control patients were examined. Virus-like particles were observed in 7 of the 16 patients with acute leukemia, 1 of the 2 patients with chronic granulocytic leukemia, and 1 of the 15 controls. Although these particles showed slight morphologic differences, many were similar in ultrastructure and in density gradient characteristics to the virus particles observed in murine leukemia and to the particles seen by other workers in plasma and tissues of patients with leukemia and lymphoma.
Cytopathic effects on WI-38 fibroblasts were observed in urine from 3 patients with leukemia. These effects resembled cytomegalovirus infection, but confirmatory tests were not carried out. Whether the virus-like particles demonstrated by electron microscopy in this study are responsible for the cytopathic effects is at present uncertain. The correlation of a morphologic structure with tissue culture activity cannot be answered until suitable in vitro assay and transformation systems are developed to purify and test these particles. This study suggests that urine may serve as a convenient source for the study and development of such test systems using the electron microscope to correlate structure with biologic activity.