Candela Laser Corporation and UCLA Tissue Typing Laboratory propose to develop a group of dye tagged monoclonal antibodies and a laser to target these dyes, for the preferential destruction of human T cells from a mixture of T and 8 cells and also acinar cells in the present of slit cells. The envisioned procedure is to attach specially modified dyes to monoclonal antibodies. The monoclonals will then carry the dye to the target cells. Laser light of a specific wavelength and pulse duration will be used to activate the dye to produce singlet oxygen, which in turn kills the cell. The development of the dyes will be carried out by Candela under the direction of Dr. Furumoto. Dr. Iwaki at UCLA will be responsible for producing and staining the monoclonals with these dyes. Candela will then determine the dye concentration taken up by the monoclonals, calculate the approximate light dose and oxygen concentration to fully activate the dye, and finally expose the specimen to an appropriate laser, to demonstrate selective killing of the target cell.