Leukocyte Signalling & Gene Expression

BIOGRAPHY

Dr. Seaman received his M.D. from Harvard Medical School in 1969. He completed his medical residency at the Massachusetts General Hospital and was a postdoctoral fellow in the Arthritis and Rheumatism Branch of the NIAMDD/NIH. He then joined the faculty of the Department of Medicine at UCSF, where he served as Chief of the Arthritis/Immunology Section at the San Francisco VA Medical Center (1981-92) and as Chief of the Medical Service at San Francisco VA Medical Center (1992-1999). In addition to his own research, he is the Director of Research for the American Asthma Foundation.

Research Interests
Our laboratory is interested in the cell surface receptors that either activate or inhibit leukocytes involved in the regulation of immunity and autoimmunity. These cells include T cells, natural killer (NK) cells, and cells of monocyte/macrophage lineage. Recent work has focused on a receptor called TREM-2 and on receptors for ferritin.
TREM-2 is expressed on activated macrophages and on cells derived from this lineage, including microglia, osteoclasts, and dendritic cells. The ligands for TREM-2 are not known, but we have demonstrated that TREM-2 preferentially binds to apoptotic cells and to a broad range of bacteria, and TREM 2 promotes the phagocytosis of both. We are studying the role of TREM-2 in response by microglia to brain injury and inflammation.

In 2005, we demonstrated in mice that TIM-2, a receptor that is structurally related to TREM 2, serves as a receptor for H-ferritin, allowing the uptake of ferritin by cells. This was the first demonstration of a receptor for H-ferritin. Tim-2 is not expressed in humans, but we have recently identified a different receptor for H-ferritin in humans.