title: Recombinant murine and human IL 1 alpha bind to human endothelial cells with an equal affinity, but have an unequal ability to induce endothelial cell adherence of lymphocytes.
abstract: Consistent with the reports of others, we have demonstrated that human peripheral blood lymphocytes adhere to cultured human umbilical vein-derived endothelial cells (EC) in vitro. In our studies adherence was increased twofold to threefold by a 6-hr preincubation of the EC with IL 1. Recombinant human IL 1 alpha induced a maximal adherence response at less than 1 U per 2 X 10(4) EC. In contrast, recombinant murine IL 1 alpha was found to be 250- to 1250-fold less active in the adherence assay, based on units of IL 1 activity defined by the murine thymocyte proliferation assay. Moreover, when EC were preincubated with excess murine IL 1, no inhibition of the adherence-inducing effect of human IL 1 was noted. To characterize further this dichotomy of biological potency of murine and human IL 1 on the adherence assay, IL 1 binding studies were initiated. Recombinant human and murine IL 1 alpha were equally effective in inhibiting the binding of 125I-labeled human and murine IL 1, based on both micrograms of protein and units of IL 1 activity. The results of this study demonstrate that although human and murine IL 1 bind with equal affinity to receptors on human EC, human IL 1 is significantly more potent at inducing the increased EC adhesiveness for lymphocytes. The implications of these results for endothelial cell IL 1 receptor function are discussed.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002448:Cell Adhesion; D004727:Endothelium / Q000166:cytology / Q000502:physiology*; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology*; D008214:Lymphocytes / Q000166:cytology*; D051379:Mice; D011971:Receptors, Immunologic / Q000502:physiology*; D017472:Receptors, Interleukin-1
chemical_list: D007375:Interleukin-1; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1