[Determination of interleukin 1].

Interleukin 1 is an essential factor of macrophage dependent T cell activation. As a method for determining IL 1 the estimation of its comitogenic activity is used with mouse thymocytes. For preparation IL 1 standards the macrophage cell line P388D1 or human leukocytes are stimulated with LPS. The mitogenic activity of the thymocytes is tested in five different mouse strains; LPS does not disturb the IL 1 determination in the concentration range between 10(2) micrograms ml-1 and 10(-3) micrograms ml-1. Contrary to the Con A reactivity the susceptibility of the thymocytes on IL 1 is developing more slowly. The age of the animals for preparation thymocytes should not be under 8 to 10 weeks. IL 1 and IL 2 inhibitors must be considered in determining IL 1.