CTLA4 and B-cell chronic lymphocytic leukemia: Since CD152 inhibits T-cell responses, increased expression of CD152 molecule on both subsets of T cells may result in an impairment of T-cell function in patients with B-CLL (Bartik et al, 1998; Lee et al, 1998; Metzler et al, 1999; Carreno et al, 2000; Frydecka et al, 2003; Wolowiec et al, 2003).