Methods of stimulating or enhancing an immune response in a host are disclosed. The methods include contacting a monocyte with 15 kD granulysin thereby producing a monocyte-derived dendritic cell. In one example, the method further includes contacting the monocyte or monocyte-derived dendritic cell with a target antigen, such as a tumor antigen or an autoimmune antigen. In another embodiment, the method includes contacting the monocyte with an additional agent that enhances maturation of dendritic cells or induces immunological tolerance. The methods are of use in vivo, in vitro and ex vivo. In another aspect, the disclosure relates to compositions and methods for the treatment of tumors.