IL21 and myeloid sarcoma: In our pilot study utilizing 10 fold-concentrated CSF derived from 16 patients with highly active inflammatory MS, we found levels of IL-7, IL-12p70, IL-17, IL-21, IL-23, granzyme B, VEGF, oncostatin M, LT-α and TNF-α below detection limit of highly sensitive cytometric bead assay in 100% of the samples [6].