Analysis of cell surface antigens by Surface Plasmon Resonance imaging

Surface Plasmon Resonance (SPR) is most commonly used to measure bio-molecular interactions. SPR is used significantly less frequent for measuring whole cell interactions. Here we introduce a method to measure whole cells label free using the specific binding of cell surface antigens expressed on the surface of cancer cells and specific ligands deposited on sensor chips using an IBIS MX96 SPR imager (SPRi). As a model system, cells from the breast cancer cell line HS578T, SKBR3 and MCF7 were used. SPRi responses to Epithelial Cell Adhesion Molecule (EpCAM) antibody and other ligands coated on the sensor chips were measured. SPR curves show a response attributable to the sedimentation of the cells and a specific binding response on top of the initial response, the magnitude of which is dependent on the ligand density and the cell type used. Comparison of SPRi with flow cytometry showed similar EpCAM expression on MCF7, SKBR3 and HS578T cells

Physical discrimination between human T-lymphocyte subpopulations by means of light scattering, revealing two populations of T8-positive cells

Light-scattering properties of human T-lymphocyte subpopulations selected by immunofluorescence were studied. Based on differences in orthogonal light scattering, two subpopulations of T8-positive cells can be distinguished. The first population (T8a) has the same orthogonal light-scattering properties as T4-positive cells, whereas the orthogonal light scattering of the second population (T8b) was about 70% larger. Orthogonal light scattering of Leu7-positive lymphocytes resembles that of the T8b population. We have studied the occurrence of the subpopulation in healthy individuals and we discuss their possible functional identification. Light-scattering properties of lymphocyte subpopulations in two patients with B-cell chronic lymphatic leukemia suggest that this observation is of clinical interest