Farrell Research Project Summary
The objective of this project is to develop molecules that can direct the cytolytic activity of CAR NK cells towards virus infected cells. Specifically, we are developing NK cell targeting strategies that will overcome HIV-1 mechanisms of NK cell evasion. These evasion mechanisms include: (i) the downregulation of NK cell activatory receptors to prevent the direct lysis of virus-infected cells; and (ii) the masking of immunogenic peptide epitopes with glycans and the limited the expression of viral proteins on the surface of infected cells. The low expression of viral proteins minimizes the opsonization of infected cells by antibodies that recognize HIV-1 proteins (e.g., envelope glycoprotein), as such, infected cells are not susceptible to NK cell mediated ADCC. Our approach to tackle this important issue is to amplify the NK cell activatory signals that can be derived from the limited number of HIV-1 envelope glycoprotein (Env) molecules expressed on HIV-1 infected cells. Specifically, we are developing Env specific monoclonal antibody-enzyme (mAb-Enz) constructs that can catalyze the covalent attachment of CAR NK cell directing molecules to the surface HIV-1 Env expressing cells. For these studies we have developed a CAR NK cell line whose cytolytic activity can be directed by the synthetic epitope FITC. As such, the enzyme activatable NK cell directing molecules are composed of anenzyme sensitive pro-quinone methide moiety, a linker and a FITC epitope. This system permits the deposition of the FITC epitope onto the cell surface and enables CAR NK cell mediated cytolysis of HIV-1 infected cells.