CD4 and hemophagocytic syndrome: Ruxolitinib demonstrated anti-inflammatory and immunomodulatory activity in hemophagocytic lymphohistiocytosis (HLH) and steroid refractory aGVHD (both resembling many characteristics of the inflammatory response against SARS-Cov-2) where induced a strong reduction of ferritin and LDH and of other inflammatory molecules such as IL-1, TNF, and MIP1a (77), coupled with a recover from T and B cell lymphopenia and the normalization of CD4/CD8 ratio (78).