Recognition of chronic myelogenous leukaemia cells by autologous T lymphocytes primed in vitro against the patient's dendritic cells.

Defects in immune responses are common in patients with chronic myelogenous leukaemia (CML). However, using dendritic cells (DCs) to promote T-cell immunity in vitro may nonetheless elicit potent specific anti-tumour responses for use in immunotherapy. Here, we show that DCs generated from CML patients had a typical dendritic phenotype and were able to stimulate autologous T cells. Three primed T-cell lines were studied in more detail in one patient. They were stimulated by autologous CML cells, but not by normal non-leukaemic cells from the patient's HLA-identical sibling. This was blocked by HLA-DR-specific, but not HLA-DQ- or HLA-DP-specific antibodies. CML-stimulated cytokine secretion, including interferon-gamma and granulocyte macrophage-colony stimulating factor, suggested a Th1-type phenotype for these sensitized anti-leukaemic T cells. This study therefore shows that cells with a functional dendritic phenotype can be generated from the blood of CML patients and are potent inducers of T-cell responses to tumour cells. This approach allows sensitization of patients' T cells by their own particular tumour without the need to identify the exact leukaemia antigens involved, and may find application in immunotherapy of CML.