In all samples from healthy donors, but not from all patients with CLL, higher pSTAT5 levels in the Tcon subset (Figure 5B,C), as well as higher percentages of CD4+ T-cells with dual expression of OX40 and CD25 (Figure 5D), were found following stimulation with the SARS-CoV-2 specific spike peptide mix (+Ag) compared to negative control (Nil) (Figure 5E,F). Here, CD4 is linked to B-cell chronic lymphocytic leukemia.