FACTORS AFFECTING THE ADHESIVENESS OF HUMAN LEUCOCYTES AND PLATELETS IN VITRO

Some factors affecting the retention of human polymorphonuclear neutrophils (PMN), lymphocytes, and platelets on a siliconized glass bead column were explored. PMN were more effectively retained when the flow rates were slow and the columns long. They were found largely on the upper portions of the columns except with rapid flow rates when they spread down the columns. PMN retention on the columns was greatest in the range 30°–43°C. Both magnesium and calcium ions were required for full adhesiveness; calcium ions alone were unable to restore adhesiveness to PMN from blood which had been treated with a chelating resin to remove divalent cations. The adhesiveness of the PMN was independent of cyanide and dinitrophenol, but was almost completely eliminated by iodoacetamide. Under all the conditions mentioned above in which adhesiveness was lost there was a concurrent loss of the usual ability of the PMN to migrate, but at least in the presence of EDTA, a capacity to change shape by pseudopod formation remained. Lymphocytes were retained on the columns to a much lesser extent than the PMN under all conditions and, within limits, this retention was not related to either flow rate or column length. Maximum lymphocyte retention occurred in the range 30°–43°C. No dependence of lymphocyte adhesiveness was shown for divalent cations, cyanide, dinitrophenol, or iodoacetamide, but such dependence is not excluded by the data obtained. Platelets were largely retained by the glass bead columns under most conditions and this was unrelated to temperature in the range 0°–50°C. Their adhesiveness was found to require either magnesium or calcium ions and to be blocked by iodoacetamide.