Biomarker measurements
IMID
BLOOD, PCT
Blood samples were collected for biomarker analysis before infusion of rituximab. B cell depletion, indicative of the effect of rituximab treatment, was measured at baseline and post-therapy using CD19 rather than CD20 to avoid measurement errors masked by rituximab. Systemic antibodies such as antinuclear antibodies (ANA) and anti-neutrophil cytoplasmic antibodies (ANCA), usually associated with IMID, were measured to determine autoimmune parameters. For inflammatory lung parameters, soluble interleukin-2 receptor (sIL-2R), procalcitonin (PCT), IL-18, and CA 15.3 were used. The CD4:CD8 ratio and chemokine ligand 18 (CCL18) were also measured before and after treatment with rituximab.