The Flow Cytometry Core will operate within the existing infrastructures of the Center for Immunology and the Harold C. Simmons Arthritis Research Center to support the research activities of Program investigators. The individual research programs proposed by these investigators have common requirements for reagents and services . The Core will consist of a Director, a Postdoctoral Research Scientist and a Research Technician. The Core will include a laboratory for preparation of samples and equipment in the Flow Cytometry Laboratory of the Immunology Center. A goal of this Core is to expand the polychromatic flow cytometry from cell surface lineage molecules to markers that include intracellular cytokines and kinases. The proposed activities of the Core will provide common and custom reagents and services that would not otherwise be available or economically feasible for the individual laboratories. The specific programs of the Core are: 1. Antibody Labeling and Resource Center 2. Quality Control Laboratory 3. Multiparameter Flow Cytometry Service Close collaboration between the Core and the principal investigators for the individual projects will be maintained in order to optimize their research productivity through utilization of Core reagents and services. In this way, redundancy will be avoided and research reagents will be provided at a reduced cost. This will allow for the centralization of certain techniques, such as high speed sorting, polychromatic flow cytometry and cytometric bead arrays, allowing for quality control and more rapid throughput.