Hematogenously disseminated fungal infections are increasing in number and have unacceptably high mortality rates despite current treatment options. New therapeutic modalities are therefore critically needed and immuno-based strategies may hold tremendous promise in the treatment of disseminated fungal infections. ? ? To treat invasive fungal infections, we propose to construct an immortal phagocytic cell-line that will specifically target leukocytes to attack fungal pathogens. We will create a genetic construct coding for a chimeric receptor formed by fusing the signal-transducing component of the Fc/gamma receptor to the antigen-binding portion of a monoclonal antibody (MAb) recognizing a fungal cell surface adhesin. By transforming a phagocytic cell-line with this chimeric receptor, we predict that the effector cells would have an enhanced ability to recognize, phagocytize, and kill fungi in vivo. Such technology is already being used to develop immunotherapies for cancer patients. ? ? We have initially targeted Candida albicans by raising a MAb (3A5) against a cell surface glycoprotein which is expressed on both the yeast and the hyphal forms. We also identified a macrophage cell-line (HL-60) that has the ability to kill C. albicans in vitro.
Our specific aims are: 1) To generate a line of Antibody Targeted Activated Killer (ATAK) cells by transforming HL-60 cells with the chimeric receptor construct. In addition, several safety controls will be incorporated into the ATAK system to ensure that the cells can be eliminated from the host once the infection has resolved. 2) To characterize the binding specificity of the chimeric receptor to C. albicans in vitro, and assess the effect of the receptor on improving HL-60-mediated fungal killing. 3) To demonstrate the efficacy and safety of ATAK cells in a neutropenic mouse model of hematogenously disseminated candidiasis. ? ? Construction of ATAK cells that can be safely infused into humans will revolutionize therapy of infections in immunocompromised patients. Furthermore, the genetic construct targeting ATAK cells to Candida can easily be adapted to any other pathogen against which a MAb has been raised. ? ?
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