Bristol Institute for Transfusion Sciences and Royal Hospital for Sick Children, Bristol, UK

Correspondence to: A Blair, Bristol Institute for Transfusion Sciences, Southmead Road, Bristol BS10 5ND, UK; Fax: 011 44 117 991 2002

We have tested the hypothesis that functional dendritic cells (DC) may be generated from patients with acute lymphoblastic leukaemia (ALL). We evaluated the production of DC from blast cells taken at presentation from nine children with ALL. Blast cells were expanded in serum-free medium supplemented with Flt3L, G-CSF, GM-CSF, IL-3, IL-6 and SCF for 7 days and subsequently stimulated with Flt3L, GM-CSF and TGF- for a further 14 days, with the addition of TNF- for the final 48 h of culture. Cultured cells had the morphological appearance of DC and expressed the DC-associated antigens CD1A (range 2-87%) and CD83 (15-44%). Expression of the co-stimulatory molecules CD80 and CD86 was increased and the majority of these cells retained their expression of CD34 (73 ± 4%) and HLA-DR (79 ± 5%). Seven of the nine ALL had a leukaemia-specific abnormality and DC generated from five of these seven cases were derived from the leukaemic clone. Leukaemic DC derived from four HLA-A*02-positive ALL pulsed with CMV-associated peptides could induce significant proliferation of peptide-specific CD8⁺ T cells. This specificity was verified using tetrameric complexes of HLA class I/antigenic peptide. DC could also be generated from cells taken at times of complete remission of ALL and from normal controls using these culture conditions. These findings show that functional DC can be generated both from ALL blasts and from patients in remission; these might be utilised in future for immunotherapeutic strategies in the treatment of ALL. Leukemia (2001) 15, 1596-1603.

acute lymphoblastic leukaemia (ALL); dendritic cells (DC); immunotherapy