TY - JOUR AU - N Porakishvili, AU - L Kardava, AU - AP Jewell, AU - K Yong, AU - MJ Glennie, AU - A Akbar, AU - PM Lydyard, PY - 2004/04/01 Y2 - 2024/03/29 TI - Cytotoxic CD4+ T cells in patients with B cell chronic lymphocytic leukemia kill via a perforin-mediated pathway JF - Haematologica JA - haematol VL - 89 IS - 4 SE - Articles DO - 10.3324/%x UR - https://haematologica.org/article/view/3028 SP - 435-443 AB - BACKGROUND AND OBJECTIVES: B-cell chronic lymphocytic leukemia (B-CLL) is a clonal expansion of CD5+B cells that accumulate due to their uncontrolled growth and resistance to apoptosis. We have previously shown that up to 50% of blood CD4+ T cells in B-CLL patients have a cytotoxicity-related CD28- CD57+ phenotype and high content of both granzyme B and perforin (PF). In this study we investigate the cytotoxic potential of these cells against autologous B-CLL cells. DESIGN AND METHODS: Blood CD4+ or CD8+ T cells were positively isolated from B-CLL patients and cultured under a range of conditions with autologous purified B-CLL cells and with bispecific [anti-CD3 x anti-CD19] antibodies. Apoptosis of labeled B-CLL cells was assessed using the change of mitochondrial membrane potential with the fluorescent dye DiOC6 and confirmed by annexin V binding. RESULTS: There was time- and dose-dependent killing of B-CLL cells by both CD8+ and CD4+ T cells and this ranged from 6.6 - 68.0% for CD4+ cells and 6.4 - 57.8% for CD8+ cells. Almost complete inhibition by concanamycin A suggests that CD4+ T cells like CD8+ T cells induced apoptosis through a perforin-mediated pathway, but not via Fas/FasL (as indicated by lack of blocking with brefeldin A), tumor necrosis factor alpha or TRAIL. INTERPRETATION AND CONCLUSIONS: This study shows that blood CD4+PF+ T cells enriched in B-CLL patients, are able to kill autologous B-CLL cells ex vivo, through bispecific antibodies via a perforin mediated mechanism. ER -