Abstract:
Chronic myeloid leukaemia (CML), is the most common myeloproliferative disease. Despite recent advances in combination chemotherapy and also stem cell transplantation, only about 7-12% of patients achieve molecular remission. Leukaemic cells use various mechanisms to avoid recognition by the immune system. Dendritic cells (DC) are professional antigen presenting cells of the immune system. These cells play a crucial role in the induction of anti—tumour immune responses. DC can be generated in-vitro from CD34⁺ stem cells or more mature CD14⁺ monocytes. The use of DC is an attractive immunotherapeutic strategy against cancer. In this study, we attempted to generate DC vaccines and investigate their activities against chronic myeloid leukaemia cells.
DC were generated from monocytes isolated and enriched from peripheral blood. The isolated monocytes were subsequently cultured in RPMI medium supplemented with GM-CSF and IL-4. On day 7, tumour lysate obtained from K562 cells, a CML cell line, was used to pulse and to initiate further maturation of the DC in a culture medium supplemented with GM-CSF, IL-4 and TNF alpha. The DC-based leukaemia vaccines were ready on Day 15.
On Day 15, the cultured cells showed matured DC morphology. Flow cytometry analysis showed strong expression of CD86 and HLA-DR. These cells did not express CD14, a monocyte marker. This showed that monocytes have been successfully differentiated to DC. Mixed leucocytes reaction (MLR) indicated that the generated DC vaccines were capable of inducing proliferative responses in allogeneic lymphocytes. The DC vaccines also exhibited considerable cytolytic activity against the K562 CML cells. In conclusion, we have successfully generated DC vaccines which are active against CML cells in vitro.
