Species preference of bovine thymocytes and fibroblasts for bovine interleukin 1

The purpose of this study was to determine whether bovine thymocytes and fibroblasts preferentially respond to bovine IL-1 as compared with human and murine interleukin 1 (IL-1). We compared equivalents units of recombinant murine and human IL-1α, and purified monocyte-derived bovine IL-1, as measured in the murine thymocyte IL-1 assay, for their ability to stimulate the proliferation of bovine thymocytes and fibroblasts. Fetal and adult bovine thymocytes responded to bovine IL-1, but in contrast, did not respond to recombinant human or murine IL-1α at the concentrations tested. Both adult and neonatal murine thymocytes responded similarly to the three IL-1 preparations. Thus, we concluded that the preferential response of bovine thymocytes for bovine IL-1 was not dependent upon the age of the thymus donor. Bovine fibroblasts also preferentially responded to bovine IL-1; fibroblast proliferation was stimulated by bovine but not human or murine IL-1. Our findings, therefore, imply that although IL-1 is highly conserved among mammalian species, its ability to stimulate the proliferation of thymocytes and fibroblasts may vary from species to species.