GENERATION OF IN VITRO B-CELL CHRONIC LYMPHOCYTIC LEUKAEMIA- SPECIFIC T CELL RESPONSES USING DENDRITIC CELLS

Abstract

Immunotherapy using dendritic cells has shown encouraging results in both haematological and non-haematological malignancies. In this study, monocyte-derived dendritic cells from patients with B-cell Chronic Lymphocytic Leukaemia were generated by culture in Interleukin-4 and Granulocyte Macrophage-Colony Stimulating Factor. Lysate-pulsed autologous dendritic cells were used as antigen presenting cells in co-culture with autologous B-cell Chronic Lymphocytic Leukaemia T-cells. B-cell Chronic Lymphocytic Leukaemia T-cells stimulated with B-cell Chronic Lymphocytic Leukaemia lysate-pulsed autologous dendritic cells showed a significant increase in cell surface expression of Interleukin-2 Receptor (CD25), Interferongamma secretion and cytotoxicity against autologous B-cell Chronic Lymphocytic Leukaemia B-cell targets hut not against targets from healthy volunteers. Responses were only stimulated by the B-cell Chronic Lymphocytic Leukaemia B cell lysate. Cytotoxicity was Major Histocompatibility Complex Class II restricted. The addition of maturation agents such as Lipopolysaccharide, Tumour Necrosis Factor-alpha and Polyriboinosinic Polyribocytidylic Acid to monocyte derived dendritic cells was unsuccessful at increasing anti-tumour responses. Pre-treatment of T cells with Interleukin-15 before stimulation by lysate pulsed autologous dendritic cells increased numbers of activated cells, cytokine secretion and specific cytotoxicity to B-cell Chronic Lymphocytic Leukaemia 8-cells. Fusion of monocyte derived dendritic cells and B-cell Chronic Lymphocytic Leukaemia B-cells generated both Major Histocompatibility Complex Class I and Class II restricted cytotoxicity to B-cell Chronic Lymphocytic Leukaemia B-cell targets. When B-cell lysates were analysed using reducing sodium dodecyl sulphate-polyacrylamide gel electrophoresis, a B-cell Chronic Lymphocytic Leukaemia specific hand at 42,000 Dalton and other patient specific bands were observed. Only the 65,000 Dalton and 42,000 Dalton hands were capable of stimulating comparable T cell responses as the whole lysate. The 65,000 Dalton band from normal healthy volunteers showed a dominant peptide that closely matched Human Serum Albumin. The 42,000 Dalton band from B-cell Chronic Lymphocytic Leukaemia patients showed a possible match with Human Actin.