A method of detecting the production of an analyte by cells in a sample, which method comprises: (i) providing an antibody capable of binding to said analyte and a first agent capable of enhancing detection of said analyte, wherein said antibody and said first agent are immobilized on the same support (ii) contacting said antibody and said agent with a sample of cells and (iii) detecting binding of said analyte to said antibody thereby detecting the production of an analyte by cells in a sample.
