CPB 69700 RESEARCH SEMINAR

DEPARTMENT OF COMPARATIVE PATHOBIOLOGY

Jee Ho Lee, M.S.

Graduate Teaching Assistant

Ph.D. Program;

Major Area: Immunology

Department of Comparative Pathobiology

Purdue University

" Regulation of Extramedullary Hematopoiesis”

Thurs., October 23, 2008

VPTH 112

3:30 pm

ABSTRACT:

Extramedullary hematopoiesis, and more specifically, extramedullary myelopoiesis (EM), is important for production of sufficient numbers of phagocytes and antigen presenting cells during immune responses but excessive EM is observed in autoimmunity and inflammation. We found that specialized effector T cells express GM-CSF and/or IL-3 (hereafter called T helper cells for myelopoiesis or Th-M cells) and positively regulate EM in the spleen. These effector T cells are distinct from Th1, Th2 and Th17 cells in their cytokine requirement for development; and they are derived from naïve T cells. Interestingly, the effector T cells are present in the spleen but not in the marrow and are greatly increased in FoxP3 deficient mice. In this regard, EM and development of naïve T-cells into Th-M cells are negatively regulated by FoxP3+ T cells. Thus, EM is both positively and negatively regulated by two distinct CD4+ T cells subsets. This reciprocal regulation of EM is thought to be important for the precise control of myeloid cell production during immune responses.