While data are lacking on the expression of CD80 and CD86 in HTLV-1 infection and pathogenesis, IFN-α enhanced CD80 expression in vitro in myeloid leukemia [32], while IFN-β has been shown to regulate CD80 and CD86 in vivo and in vitro in MS [33,34]. Here, CD80 is linked to myeloid leukemia.