It is important to mention that they administered vitamin A as a single oral dose of 4,000 IU/kg prior to conditioning, before the start of the inflammatory environment that occurs later in the SCT process where RA can play an important role in CD4+ T-cell activation (104) and effector function since RA can have complex pro- or anti-inflammatory functions depending on the context (105). Here, CD4 is linked to rheumatoid arthritis.