Figure 2. Methods of loading dendritic cells (DCs) with tumour antigens. (A) DCs loaded with class I restricted peptides are only able to prime CD8+ T-cells. Lack of antigen-specific T-cell help may result in a suboptimal immune response. (B) DCs loaded with whole antigens are able to prime both CD8+ and CD4+ T-cells. (C) DCs can also be transduced with genes encoding tumour antigens, allowing the activation of both CD8+ and CD4+ T-cells. Tumour antigen expression within the DCs provides the cells with a renewable source of antigen.