Association of Electron-Dense Particles With Human Acute Leukemia

Abstract

Electron-dense particles, bearing some morphologic similarities to viruses described in the avian and murine leukemias, have been identified by electron microscopy in peripheral blood from 8 of 56 patients with acute leukemia, from none of 51 random normal controls, and from 1 of 36 age- and sex-matched normal controls. The particles are spherical bodies with 1 or 2 concentric membranes and often a centrally located nucleoid. Their diameter is 800 to 900 A. When material was available, negative staining with phosphotungstic acid revealed a tail-like protrusion extending from an angular head. As the viral nature of these particles remains unproved and their relationship to the etiology of acute human leukemia is not established, the present significance of this observation must be limited to its use as one criterion for the selection of human leukemic materials to undergo biological testing.