There are, to date, no validated biomarkers or head-to-head RCTs of biologics to guide choice of biologic agent in axSpA. While there are now two head-to-head studies of a TNF inhibitor (TNFi) vs an IL-17 inhibitor (IL-17i) in psoriatic arthritis. Recommendations refers to biological DMARDs (bDMARDs) including TNFi and IL-17i for patients with high disease activity despite the use (or intolerance/contraindication) of at least two non-steroidal anti-inflammatory drugs (NSAIDs) in axial SpA (axSpA) and in failure of a strategy including methotrexate for psoriatic arthritis. A tool to help us to decide which bDMARDs to use is necessary. In SpA, the method of determination of IL17 seems to be questionable. The determination of cytokines after stimulation of immune cells in patients with active SpA requiring a biological treatment could provide us with a tool to assist in the choice of therapy. The aim of the study was to show the feasibility of cytokine assay following lymphocyte stimulation in active SpA requiring biological treatment. And secondly, to show the predictive character of this expression on the therapeutic response at three months after the implementation of a biological treatment.