Absorption of macrophage aggregating factor by guinea-pig peritoneal exudate cells.

Lymphokine (LK)-induced aggregation of peritoneal exudate cells (PEC) has been measured using a quantitative technique. Aggregating activity could be removed from LK preparations by absorption of these with PEC and, in addition, the absorbing PEC, on further incubation themselves aggregated. Absorption of aggregating activity to PEC was rapid, being easily measurable at between 2-5 and 10 min although it was difficult to demonstrate at 30 min. Trypsinized PEC were as effective as normal PEC in absorbing aggregating activity. alpha-L-fucose inhibited LK-induced PEC aggregation and this inhibition showed some specificity in being significantly greater than that obtained with D(+)galactose. However, measurement of the subsequent aggregation of PEC which had been pulse exposed to LK, in the presence of alpha-L-fucose, showed that alpha-L-fucose had no effect on this aggregation. It is concluded that the measurement of aggregating activity can be used to study LK binding to PEC, although the relationship of this binding to the inhibition of aggregation obtained with alpha-L-fucose is not clear.