However, in two previous clinical trials of high dose vitamin D supplementation (≥10,000 IU/day) in people with MS, no effects on naïve B or other B cell frequencies were observed46,47, but in the study of Sotirchos et al., wherein participants received 20,000 IU/day for 6 months, reductions in IL-17+ and effector memory CD4+ T cells were reported after the intervention47. Here, CD4 is linked to myeloid sarcoma.