Relationships between different functional properties of human monocytes.

Various methods for measuring monocyte numbers and function in human blood are compared. The assays used were: phagocytosis of antibody-sensitized sheep red cells; staining for diffuse non-specific esterase activity; capacity to adhere to polystyrene and ability to lyse human A1 red cells sensitized with allogeneic anti-A1 antibody. The following conclusions are drawn from the results: (1) Previous observations showing that sensitized A1 red cells are lysed by phagocytic cells and not K cells are confirmed. (2) Granulocytes lyse sensitized A1 red cells more rapidly than monocytes and this assay is only useful for assessing monocyte function if granulocytes are first removed from preparations. (3) Phagocytosis is important in the lysis of sensitized A1 red cells by monocytes. (4) Esterase positive cells correlate significantly with the number of cells phagocytosing sensitized sheep red blood cells, r = 0.83 (P less than 0.001) and with the number of cells adhering to polystyrene, r = 0.53 (P less than 0.05). (5) The lysis of sensitized A1 red cells correlated significantly with esterase positive cell numbers, r = 0.57 (P less than 0.001) and phagocytosis of sensitized sheep red cells, r = 0.50 (P less than 0.01 but not with the numbers of adherent cells, r = 0.34 (P greater than 0.05).