In contrast to the inhibitory effects of RBC on CD19+ B cells from healthy donors, which were replicated for the corresponding minor CD5+ CD19+ B‐cell fractions (Figure S5a), the addition of RBC failed to reduce the expression of HLA‐DP/DQ/DR (Figure 4e) by CD5+ CD19+ B cells from patients with CLL. Here, CD5 is linked to B-cell chronic lymphocytic leukemia.