The present invention relates generally to a fusion protein that when displayed on a cell can convert a negative signal into a positive signal in the cell. The fusion protein is a chimeric protein in that the protein comprises at least two domains, wherein the first domain is a polypeptide that is associated with a negative signal and the second domain is a polypeptide that is associated with a positive signal. Thus, the invention encompasses switch receptors that are able to switch negative signals to positive signals for enhancement of an immune response.