In addition, literature data confirm that CLL cells bear the phenotype of activated B cells based on overexpression of the classical activation markers CD23, CD25, CD69 and CD71, and under-expression of CD22, Fcγ IIb, CD79b, and immunoglobulin D, which are down-regulated by cell triggering and activation [34]. This evidence concerns the gene CD69 and B-cell chronic lymphocytic leukemia.