This recombinant Jurkat cell line is a biologically relevant system to measure activation of the IL-15 cytokine receptor by IL-15. The cells were engineered for constitutive expression of human CD122 (IL-15Rβ; IL-2Rβ; NM_000878.4), and conditional expression of firefly luciferase driven by STAT5 response elements located upstream of the minimal TATA promoter. Expression of CD122 allows formation of a functional IL-15 receptor at the surface of Jurkat cells, which naturally express high levels of CD132 (also known as IL-15 receptor subunit γc). Activation of the STAT5 signaling pathway in response to IL-15 or IL-15 analogs can be monitored by measuring luciferase activity.