Induction of lymphocyte locomotor capacity by a substratum-dependent factor from mononuclear cells

Media conditioned by human mononuclear cells contain a factor which renders freshly purified T lymphocytes motile and which is distinct from interleukin 1 and interleukin 2. The motility induced by this factor is morphologically indistinguishable from spontaneous lymphocyte motility. The factor is most effective when allowed to attach to the substratum. The effect of the factor on lymphocyte motility is detectable within 30 min but increases over a period of several hours. The relatively rapid action taken together with the ability to interact with both lymphocytes and the substratum point to the possibility that the factor rendering lymphocytes motile is a ligand which mediates cell-substrate adhesion. Attempts to characterize this putative ligand using gel filtration chromatography yielded activity peaks at 500 to 600 kDa.