Analysis of the expression of critical activation/interaction markers on peripheral blood T cells in B-cell chronic lymphocytic leukaemia: evidence of immune dysregulation

B-cell chronic lymphocytic leukaemia (B-CLL) is characterized by an accumul ation of clonal malignant B cells. The intrinsic characteristics that permi t this accumulation have been extensively studied and described. However, i t is possible that proliferation and survival of this malignant clone is fa cilitated by a disruption in the interaction between B and T cells that nor mally regulate the immune system, In this study, using flow cytometry and c ell culture techniques, marked abnormalities of the expression of certain k ey activation and interaction molecules on the peripheral blood T cells of patients with B-CLL were demonstrated. in particular, on comparison with no rmal controls, there was a marked reduction in the number of circulating T cells expressing CD25 (interleukin 2 receptor) (P = 0.007), CD28 (P = 0.01) and CD152 (CTLA-4) (P = 0.001). There was also a reduction in the number o f circulating T cells expressing CD4 (P = 0.03), CD5 (P = 0.05) and CD11a ( P = 0.01). There was no difference in the number expressing T-cell receptor ap (P = 0.1), CD8 (P = 0.4), CD54 (P = 0.4) and CD154 (P = 0.5), and the o nly marker expressed on a greater number of circulating T cells in B-CLL pa tients was HLA-DR (P = 0.05). These results suggest that there is a profoun d T-cell dysregulation that may contribute to the survival of the malignant B cells in patients with B-CLL and to the related autoimmune phenomena of the disease.