( Scientists here have made a major disco...)Scientists identify new model Of NK cell development

Scientists have believed for years that human NK cells are generated in bone marrow, but Michael Caligiuri, director of the OSU Comprehensive Cancer Center and the senior author of the study, says research in his laboratory shows that the precursors to NK cells are actually found in cellular nurseries deep inside the body's lymph nodes.

The findings, appearing in the Mar. 22 issue of the journal Immunity, may offer clinicians new direction in determining how to manipulate this cell type in enhancing immune responses to cancer.

"This study is fundamentally about understanding the immune system more fully so we can help patients," says Caligiuri.

A major arm of the body's defense system is made up of lymphocytes, cells that fall broadly into three categories ?T cells, B cells and NK cells.

Although all lymphocytes stem from a common source ?progenitor cells in the bone marrow ?they take different paths in developing into full-fighters in the immune system. For example, cells destined to become T cells, sophisticated and highly focused killer cells, are released into the bloodstream and migrate to the thymus where they learn their role. In contrast, B cells, which make antibodies, remain and mature in the bone marrow. Until now, scientists thought NK cells did the same.

But Caligiuri, working with Aharon Freud, the lead author of the study and a doctoral candidate in Caligiuri's laboratory, had noted other work showing that mice lacking lymph nodes also lacked NK cells. In addition, in earlier research in Caligiuri's laboratory, scientists had identified two distinct subsets of human NK cells (referred to as CD56 bright and CD56 dim cells) and they
'"/>

Source:Ohio State University