The ability to measure successfully the levels of Th-1 or Th-2 cytokines during an in vitro antigen-driven, polyclonal T-cell response has proven to be more difficult than expected. Here we describe the development of a highly sensitive cell-based ELISA (celELISA) technique for the detection of murine Th-1 and Th-2 cytokines. The celELISA combines the quantification aspects of the conventional sandwich ELISA with the sensitivity of the ELISPOT assay. The celELISA was particularly useful for the improved detection of IL-2, IL-4, and to a lessor extent, IFN-gamma. (C) 1997 Elsevier Science B.V.