ART was associated with a 7-fold increase in the risk of MS exacerbation and with a 9-fold increase in the risk of enhanced disease activity as seen in MRI scans of lesions. Worsening was associated with higher number of cells producing IL-8, IL-12, IFNc, and TGF-b, as well as increased VEGF production by CD4. T cells and CXCL-12 plasma levels, all GnRH-mediated. Here, CXCL12 is linked to myeloid sarcoma.