The nTreg pSTAT5 signaling response, associated with an increase in aTreg/nTreg ratio, which was more significant in samples from our CLL patients during SARS-CoV-2 antigen-specific stimulation, suggests the role of IL-2-dependent STAT5 signaling in the differentiation of nTreg into aTreg. Here, IL2 is linked to B-cell chronic lymphocytic leukemia.