1
Department of Pathology University of California,
San Francisco, California 94143, USA
2
Immunology Research DivisionDepartment of Pathology
Brigham & Women's Hospital and Harvard Medical School Boston
, Massachusetts 02115, USA Email:
aabbas@itsa.ucsf.edu
Many different T-cell co-stimulatory molecules have been recently discovered.
Determining exactly how many there are, why there are so many and what they
all do is the next task (1365−1369).
