Uromodulin: a specific inhibitor of IL-1-initiated human T cell colony formation.

Uromodulin, an 85 kDa naturally occurring immunosuppressant, was found to selectively and specifically inhibit the ability of IL-1 to induce colony responses by highly enriched suspensions of PHA-stimulated T lymphocytes. Dilutions of 1 x 10(-8) M completely blocked the colony growth of T lymphocytes cultured with 50 U/ml IL-1; 1 x 10(-9) M dilutions reduced scores by 83%. By contrast, uromodulin did not inhibit the responses of unseparated mononuclear cells, isolated T lymphocytes cultured with irradiated adherent cells, or stimulated T cells whose growth was initiated by either IL-2 or a soluble factor derived from Raji cells.