Studies on lymphokine-induced macrophage aggregation. Specificity and quantitative aspects.

A method for the quantitative measurement of macrophage aggregation by lymphokine preparations has been described previously. This involved the continuous measurement of the light absorbance of stirred suspensions of guinea pig peritoneal exudate cells (PEC). We now show that using a modified method, both aggregation of normal PEC, induced by preformed lymphokine, and direct aggregation of sensitized PEC with specific antigen can be measured. The method is suitable for the assay of large numbers of samples. Aggregation is shown to be immunologically specific for two antigens (bovine gamma-globulin and ovalbumin) and to be partially inhibited by sugars which inhibit migration inhibitory factor activity (rhamnose and fucose).