IFNG and B-cell chronic lymphocytic leukemia: Moreover, IFN-γ ELISpot assays, using PBMCs from HLA-matched CLL patients, revealed preexisting peptide-specific memory T cells targeting 2/9 (22%) and 4/5 (80%) HLA class I- and HLA class II-restricted warehouse peptides in up to 29% and 50% of CLL patient samples, respectively (Figures 3C, D, Supplementary Figure 5 and Table 1).