A SENSITIVE AND SPECIFIC BIOASSAY FOR THE DETECTION OF HUMAN INTERLEUKIN-10

Interleukin-10 (IL-10) is a novel cytokine that is produced by T cells , macrophages, B cells and keratinocytes. It has been shown to inhibit cytokine production and proliferation by T cells when macrophages are used as accessory or antigen presenting cells. Monokine production by macrophages is effectively downregulated by IL-10 and it can be used as a growth factor by CD4, CD8 and gamma/delta positive T cells as wel l as mast cells and B cells. It is because of these pleiotropic immuno regulatory effects that the detection of IL-10 in the supernatants of T cells, B cells, macrophages and other cells is important for many sc ientific questions. Here we describe a simple and sensitive bioassay s pecific for human IL-10 using the IL-10 dependent growth of the mouse mast cell line D36. Our data show that this assay is not crossreactive with hIL-1 beta, hIL-2, hIL-3, hIL-4, hIL-5, hIL-6, hIL-9, hIL-12, hG M-CSF and hTNF-alpha and that it can be completely blocked by an antib ody against human IL-10. The hIL-10 induced growth of the D36 cell lin e is dependent on the presence of mIL-4. Human IL-10 can be measured i n a concentration range from approximately 10 U/ml to 0.05 U/ml. This assay is only of limited use for the measurement of IL-10 in human blo od samples since it is inhibited by the presence of human serum.