The immune system is a network of interacting biological cells. The molecular events that lead to the activation and regulation of these cells often occur at the cell surface. However, little is known about the arrangement, motions and interactions of the participating cell-surface molecules. To examine these phenomena, we construct model cell membranes on planar supports from purified or synthesized molecules.

Recently developed techniques in laser-based fluorescence microscopy can then be employed to examine the behavior of select fluorescently labeled molecules at or near the supported planar membranes. We are particularly interested in developing and applying methods in total internal reflection fluorescence microscopy and in fluorescence correlation spectroscopy. Potentially measurable are lateral and rotational diffusion and flow, two-dimension concentration gradients, orientation distributions, conformational changes, the formation of small or large oligomers, and association/dissociation kinetic rates, both for molecules in solution with specific membrane sites and for molecules within the membrane plane.

This research is significant not only in the basic understanding of the immune system, but also in other areas of cell-cell communication and cell membrane biophysics, in the physics of two-dimensional fluids, and in biotechnology.