TNFSF13B and pulmonary arterial hypertension: Our results can be summarized as follows: 1/in a discovery cohort of SSc patients, we identified associations of B cell biomarkers with SSc phenotype, disease activity and severity, ILD and PH; 2/in this discovery population as well as in an independent validation cohort enriched with SSc-PAH patients, serum IgG, β2-microglobulin, BAFF, sBCMA and sCD23 levels were associated with PH status and/or clinical markers (Table 8); 3/B cells from SSc patients showed differential production of various pro- and anti-angiogenic mediators compared to HC.