Here, we describe a sensitive and specific assay and kit for the detection of chemokines having activity that is upregulated by Th-1 cytokines (such IFN-γ) and chemokines that upregulate the activity of Th-1 cytokines (such as IFN-γ). In a typical embodiment, detection of the chemokine monokine induced by gamma interferon (MIG) provides a measure of the biological effect of IFN-γ rather than direct quantitation of IFN-γ or IFN-γ secreting cells per se. Upregulation of MIG expression was observed following in vitro activation of PBMC with defined CD8+ T cell epitopes derived from influenza virus, CMV, or EBV, and in all cases this was antigen-specific, genetically restricted and dependent on both CD8+ T cells and IFN-γ. Responses as assessed by the MIG assay paralleled those detected by conventional IFN-γ ELISPOT, but the magnitude of response and sensitivity of the MIG assay were superior. Our data validate this novel method for the detection of high as well as low levels of antigen-specific and genetically restricted IFN-γ activity or MIG.