Abstract: The invention is related to peptide constracts, i.e., polypeptides obtained by linking together two or more peptides based on or derived from different molecules, which are useful in the treatment or prevention of cancer or the treatment of autoimmune diseases and compositions containing same, methods for producing same, and methods for using same: wherein the peptide constructs have the formula P1-x-P2 where P2 is a peptide associated with forms of cancer or an autoimmune condition and P1 is a peptide which will bind to a class of immune cells such as dendritic cells. The peptide construct can cause the maturation of immature dendritic cells to a more mature state. The peptide construct or the more mature dendritic cells can be administered to a subject to a modulate or to initiate an immune response against cancer cells, and can be sued with dyes, radioisotopes, or therapeutic agents for detection of the immune target and/or treatment of cancer and autoimmune conditions.