TY - JOUR T1 - Cytokines in pulmonary arterial hypertension: consider sensitivity when using multiplex technology JF - European Respiratory Journal JO - Eur Respir J SP - 547 LP - 549 DO - 10.1183/09031936.00000114 VL - 44 IS - 2 AU - Denis Monneret Y1 - 2014/08/01 UR - http://erj.ersjournals.com/content/44/2/547.abstract N2 - To the Editor:Cracowski et al. [1] have recently published an interesting substudy in which they analysed the association of 17 baseline plasma cytokine concentrations with mortality in patients suffering from pulmonary arterial hypertension (PAH), using multiplex technology. The authors showed that four cytokines were independently associated with an increase in the adjusted hazard of mortality. Previously, Soon et al. [2] demonstrated that elevated levels of cytokines in PAH also predict survival over a 5-year period. Both these studies reinforce the increasing evidence that inflammation is associated with PAH remodelling.Nevertheless, it is known that concentrations of circulating cytokines are very low, in the pg·mL−1 range, requiring highly sensitive methods. In the letter by Cracowski et al. [1], despite a well-defined design and a robust statistical analysis, as previously described [3], no information is provided about the analytical performances of the method for cytokine quantification. In order to strengthen such cytokine-based clinical studies, the sensitivity of multiplex technology is herein discussed.table 1 shows the mean … ER -