Leucocyte chemotactic activity in the parallel bioassay of guinea--pig lymphokines.

This paper describes the application of parallel bioassay to determine the extent to which the leucocyte chemotactic activity of guinea-pig lymphokine preparations is associated with their lymphocyte mitogenic, inflammatory (increased vascular permeability) and macrophage migration inhibitory activities. A convenient test of chemotactic activity was devised whereby Coulter counter determinations were made of the number of peritoneal exudate cells passing through a Nuclepore membrane into the medium of the lower (test) compartment of a chemotaxis chamber. Symmetrical parallel line (2+2) dose assays were used to obtain potency ratio estimates of the chemotactic activity of seven lymphokine preparations whose mitogenic, inflammatory and migration inhibitory activities were already known. Statistical analysis of the results revealed a clear dissociation of chemotactic activity from mitogenic and migration inhibitory activities; but with six of the seven lymphokine preparations, a marked similarity was revealed between their chemotactic and inflammatory activities. Cytological studies showed that although the lymphokine preparations were chemotactic for different cell types, there was a preferential migration of neutrophils and the smaller mononuclear cells. The demonstration by parallel bioassay of an association between the ability of lymphokine preparations to increase vascular permeability in vivo and to promote chemotaxis of leucocytes in vitro is viewed in relation to the possible role of lymphokine in inflammatory processes.