Human Macrophages and Dendritic Cells Can Equally Present MART-1 Antigen to CD8.sup.+ T Cells after Phagocytosis of Gamma-Irradiated Melanoma Cells

• Published in: PloS one 2012-07, Vol.7 (7), p.e40311
• Main Authors: Barrio, Abes, Riad, Colombo, Marina, Pizzurro, Gabriela, Boix, Charlotte, Roberti, Gélizé, Emmanuelle, Rodriguez-Zubieta, Mariana, Mordoh, José, Teillaud, Jean-Luc
• Format: Article
• Language: English
• Subjects: Antibodies; Dendritic cells; HLA antigens; Macrophages; Melanoma; T cells; Vaccination; Vaccines
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0040311

Dendritic cells (DC) can achieve cross-presentation of naturally-occurringtumor-associated antigens after phagocytosis and processing of dying tumorcells. They have been used in different clinical settings to vaccinate cancerpatients. We have previously used gamma-irradiated MART-1 expressing melanomacells as a source of antigens to vaccinate melanoma patients by injectingirradiated cells with BCG and GM-CSF or to load immature DC and use them asa vaccine. Other clinical trials have used IFN-gamma activated macrophagekiller cells (MAK) to treat cancer patients. However, the clinical use ofMAK has been based on their direct tumoricidal activity rather than on theirability to act as antigen-presenting cells to stimulate an adaptive antitumorresponse. Thus, in the present work, we compared the fate of MART-1 afterphagocytosis of gamma-irradiated cells by clinical grade DC or MAK as wellas the ability of these cells to cross present MART-1 to CD8.sup.+ T cells. Using a high affinity antibody against MART-1, 2A9, which specificallystains melanoma tumors, melanoma cell lines and normal melanocytes, the expressionlevel of MART-1 in melanoma cell lines could be related to their ability tostimulate IFN-gamma production by a MART-1 specific HLA-A*0201-restrictedCD8.sup.+ T cell clone. Confocal microscopy with Alexa Fluor®.sup.647 -labelled2A9 also showed that MART-1 could be detected in tumor cells attached and/orfused to phagocytes and even inside these cells as early as 1 h and up to24 h or 48 h after initiation of co-cultures between gamma-irradiated melanomacells and MAK or DC, respectively. Interestingly, MART-1 was cross-presentedto MART-1 specific T cells by both MAK and DC co-cultured with melanoma gamma-irradiatedcells for different time-points. Thus, naturally occurring MART-1 melanomaantigen can be taken-up from dying melanoma cells into DC or MAK and bothcell types can induce specific CD8.sup.+ T cell cross-presentationthereafter.