CD4 and B-cell chronic lymphocytic leukemia: Skewing towards a more pro-tumoral Th2 phenotype in which CD4+ T-cells produce interleukin (IL) 4 is described [105,106,107], while skewing in both progressive and non-progressive CLL patients towards a Th1 phenotype also has been reported, in which CD4+ T-cells produce more interferon y (IFNy), possibly contributing to an anti-tumor response [103,108].