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J. Exp. Med.,
Volume 189, Number 5, March 1, 1999 871-876
By










From the * Laboratory of Tumor Immunology, the In this study we used TEPITOPE, a new epitope prediction software, to identify sequence segments on the MAGE-3 protein with promiscuous binding to histocompatibility leukocyte antigen (HLA)-DR molecules. Synthetic peptides corresponding to the identified sequences were
synthesized and used to propagate CD4+ T cells from the blood of a healthy donor. CD4+ T
cells strongly recognized MAGE-3281-295 and, to a lesser extent, MAGE-3141-155 and MAGE-3146-160. Moreover, CD4+ T cells proliferated in the presence of recombinant MAGE-3 after processing and presentation by autologous antigen presenting cells, demonstrating that the
MAGE-3 epitopes recognized are naturally processed. CD4+ T cells, mostly of the T helper 1 type, showed specific lytic activity against HLA-DR11/MAGE-3-positive melanoma cells.
Cold target inhibition experiments demonstrated indeed that the CD4+ T cells recognized
MAGE-3281-295 in association with HLA-DR11 on melanoma cells. This is the first evidence
that a tumor-specific shared antigen forms CD4+ T cell epitopes. Furthermore, we validated
the use of algorithms for the prediction of promiscuous CD4+ T cell epitopes, thus opening
the possibility of wide application to other tumor-associated antigens. These results have direct implications for cancer immunotherapy in the design of peptide-based vaccines with tumor-specific CD4+ T cell epitopes.
Cancer Immunotherapy and Gene Therapy
Program, and the § Laboratory of Molecular Tissue Typing and
Immunochemistry Unit, Department of
Biology and Technology (DIBIT), Scientific Institute H. San Raffaele, 20132 Milan, Italy; ¶ Roche
Milano Ricerche, 20132 Milan, Italy; ** Roche Discovery Technologies, Hoffman-La Roche, Inc.,
Nutley, New Jersey 07110; and 
Departement Chirurgie, Kantonsspital, CH-4031 Basel,
Switzerland
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