A type of white blood cell. T lymphocytes are part of the immune system and develop from stem cells in the bone marrow. They help protect the body from infection and may help fight cancer. Also called T cell and thymocyte.
![Blood cell development](/books/NBK65951/bin/CDR0000526538.gif)
Figure
Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.