Functional discrimination between interleukin 6 and interleukin 1.

In this study we have investigated the specificity of bioassays in which interleukin (IL) 1 and/or IL 6 are active. The thymocyte assay cannot be used to discriminate between IL 1 and IL 6; both monokines are active in this assay. Moreover the detection limit for both IL 1 and IL 6 is around 100 pg/ml. IL 6 activity can be measured with a murine hybridoma cell line (B9). The detection limit for human as well as murine IL 6 is about 0.5 pg/ml. The assay is specific for IL 6 and is not influenced by a variety of other cytokines except for murine IL 4 which shows some activity in this variety of other cytokines except for murine IL 4 which shows some activity in this assay. IL 1 can be measured specifically with D10 cells. The detection limit for IL 1 alpha and IL 1 beta is around 1 pg/ml whereas IL 6 is not active in this assay at all. Upon stimulation by IL 1 and/or IL 2 D10 cells produce IL 6. However, this IL 6 does not seem to be involved in the proliferation of these cells.