The purpose of this centralized core resource is to provide (1) expertise in experimental design, and (2) technical and equipment support in the performance of experiments for research projects utilizing flow cytometry in the investigation of basic and clinical questions relating to HIV pathogenesis. The prime goal is to provide the intellectual environment and the material resources to enable junior investigators to apply flow cytometry technology to their projects and to encourage established investigators to initiate innovative pilot studies. To this end, several different funding sources (UCSD, CFAR, VA AIDS Research Center, VAMC Research Core) have been integrated to support and expand our flow cytometry facility to meet the research needs of the San Diego academic community. The CFAR award continues to be an integrate component in this endeavor. The flow cytometry facility contains three major pieces of equipment that are used to perform highly complementary functions. A Coulter Elite sorter with dual lasers plus a UV laser for calcium flux and cellular DNA is quantitation is utilized primarily for multi-parameter cell analyses. A Becton-Dickinson FACStar Plus sorter, with a fifth detector for 3-color analysis, operates as a high efficiency cell sorter for non-biohazardous or fixed cell samples. A recently funded, high speed, dual laser cell sorter (FACS Vantage Turbo) is being acquired and housed in a restricted BSL-2 space; it will perform both rare events recovery, needed for stem cell research and live cell sorting of HIV-infected specimens. Dedicated technicians operate these flow cytometers, and work is performed on a recharge basis for individual investigators. Support personnel include a highly experienced senior technician and a more junior, trained technician; a mid-level experienced technician is being recruited currently to operate the new cell sorter for work with biohazardous material. The core director, who is experienced in flow cytometry and research application, provides consultation on experimental design and data interpretation to investigators using the facility. In the past three years, CFAR resources have enabled the flow cytometry core to support HIV research projects in such diverse areas as: Kaposis sarcoma (CA67394), clonal B-cell development (AI34001), macrophages functions (AI35258, NS31060), cytokine responses (AI38858), therapy- induced immune restoration (AI27670), gene therapy (DK49618, AI36612), antiviral drug development (GM24979), and pediatric AIDS (AI39004). With the expanding application of flow cytometry to areas of biomolecular research, continued CFAR support will be crucial to providing the infrastructure to take advantage of new scientific opportunities in HIV research.