Influence of physical factors on morphological features of mononuclear cells in human blood. Lymphocyte-monocyte interconversion.

The recovery of monocytes, following density sedimentation of human peripheral blood, was previously observed to be greater than 100%. An explanation was sought in the present study. No evidence for erroneous estimation of these cells was found. Rather, the data suggest that lymphocytes may take on the appearance of monocytes as a consequence of cytocentrifugation. This phenomenon does not appear to be influenced by the osmolality or viscosity of the suspending medium, nor by the process of sedimentation. Moreover, polymorphonuclear leukocytes do not seem to participate in the process of transformation, which may depend instead on the transfer of cytoplasm from monocytes to lymphocytes.