Changes of the electrophoretic mobility of human monocytes are regulated by lymphocytes

The changes of the electrophoretic mobility (EM) of human monocytes during invitro maturation into macrophages were investigated. Incubation of isolated monocytes for longer than 4 days was always accompanied by an increase of the EM of the monocytes. This increase of the EM could only be inhibited when lymphocytes were incubated together with the monocytes. The inhibitory effect of the lymphocytes was optimal when the culture medium was supplemented by autologous plasma and when the cell suspension was kept in teflon beakers, but it was reduced when the culture medium was supplemented by fetal calf serum (FCS) and when the cell suspension was kept in polystyrene dishes. The macrophages, which showed increased EM after 10 days of incubation, had equal antibody‐dependent cell‐mediated cytotoxic (ADCC) activity but lower plaque‐forming activity than the macrophages which retained their original EM during incubation. The finding of macrophage sub‐populations which differ in their EM provides a good opportunity to isolate and further investigate macrophages, which may have different biological activities.