Melanoma-associated chondroitin sulfate proteoglycan (MCSP) (also known as high molecular weight-melanoma-associated antigen) represents an interesting target antigen for cancer immunotherapy which is expressed on human melanomas and other tumors such as breast carcinomas, gliomas, neuroblastomas and acute leukemias. MCSP seems to play an important functional role in melanoma as it is involved in tumor cell migration, invasion and angiogenesis. In this study, we isolated CD4+ T helper cells from the blood of a healthy donor, recognizing a peptide from the MCSP core protein presented by HLA-DBR1*1101 molecules. T cell reactivity against the identified peptide could be detected in the blood of healthy donors and melanoma patients. MCSP specific T cells from the blood of a patient could be readily expanded by repeated peptide stimulation and recognized MCSP and HLA-DR expressing tumor cells. Our findings suggest that vaccination against MCSP helper T cell epitopes might be a promising approach to fight melanoma. © 2009 Wiley-Liss, Inc.