Cytotoxicity of Vγ9Vδ2 T cells towards Colon Cancer Cells

Immunotherapies for cancer are widely studied at present. We are currently studying a specific form of “Vγ9Vδ2 T cells” found in the peripheral blood of healthy donors that can be used for the killing of HT-29 colon cancer cells. In order to determine the cytotoxicity of effectors, Vγ9Vδ2 T cells towards target cells, HT-29, it is important to first evaluate the absolute number of Vγ9Vδ2 T cells in a mixed cell population, and next to determine the phenotypic characterization, their activity and cytotoxicity in the presence of target cells. A flow cytometry and bead based assay was developed to evaluate the absolute number of Vγ9Vδ2 T cells in a mixed cell population. Peripheral Blood Mononuclear Cells (PBMCs) were surface stained with monoclonal antibodies (MoAbs) conjugated to fluorochromes that are cross reactive to cell surface markers such as CD3 (T Lymphocytes), γδ2 and were mixed with fluorophore beads. In these assays, no washes and centrifugation steps were performed after the cell surface staining and bead addition. The absolute cell counts were evaluated based on referencing a known concentration of beads. In addition, quantification assays were also performed to measure the cell and bead loss on surface staining that included washes and centrifugation steps and thus found a higher percentage loss of cells than beads. Immunophenotyping assays with four color staining were performed to monitor the phenotypic differentiation of effector cells based on cell surface markers CD27 and CD45RA. Only the naïve (CD27+CDRA+) and terminally differentiated effector memory (CD27-CD45RA+) were identified on the assays performed using Vγ9Vδ2 T cells of different donors. A flow cytometry based cytotoxicity (FCC) assay was completed to monitor the effector cell activity (CD69+) in the presence and absence of target cells and also the cytotoxicity was measured based on % specific lysis of target cells at four different effector to target (E:T) cell ratios. Only preliminary data were obtained for the FCC assay and the ...