1. ¹Leukaemia Research Laboratory, University of Sydney, Westmead Hospital, Sydney NSW 2145, Australia
2. ²Molmed, Via Olgettina 58, Milan 20132, Italy
3. ³Cancer Immunotherapy and Gene Therapy Program, Cancer Gene Therapy Unit, Scientific Institute H San Raffaele, Via Olgettina 58, Milan 20132, Italy

Correspondence: Associate Professor D Gottlieb, E-mail: david_gottlieb@wmi.usyd.edu.au

Revised 5 June 2006; Accepted 6 June 2006; Published online 4 July 2006.

Abstract

Lymphodepletion and infusion of autologous expanded tumour-infiltrating lymphocytes is effective therapy for patients with malignant melanoma. Antitumour responses are likely to be mediated by HLA class I- and II-restricted immune responses directed at tumour antigens. We assessed whether the peripheral blood of normal HLA-matched siblings of patients with melanoma could be used to generate lymphocytes with antimelanoma activity for adoptive immunotherapy after allogeneic blood or marrow transplantation. Melanoma cell lines were derived from two donors and were used to stimulate the mononuclear cells of three HLA-identical siblings. CD4⁺ clones dominated cultures. Of these, approximately half were directly cytotoxic towards recipient melanoma cells and secreted interferon- in response to tumour stimulation. More than half of the noncytotoxic clones also secreted interferon- after melanoma stimulation. No CD4⁺ clones responded to stimulation with recipient haemopoietic cells. The majority of CD8⁺ clones directly lysed recipient melanoma, but did not persist in long-term culture in vitro. No crossreactivity with recipient haemopoietic cells was observed. The antigenic target of one CD4⁺ clone was determined to be an HLA-DR11-restricted MAGE-3 epitope. Antigenic targets of the remaining clones were not elucidated, but appeared to be restricted through a non-HLA-DR class II molecule. We conclude that the blood of allogeneic HLA-matched sibling donors contains melanoma-reactive lymphocyte precursors directed at tumour-associated antigens. Adoptive immunotherapy with unselected or ex vivo-stimulated donor lymphocytes after allogeneic stem cell transplantation has a rational basis for the treatment of malignant melanoma.