In vitro requirement for periostin in B lymphopoiesis.

B lymphopoiesis arrests in rabbits by 4 months of age. To identify molecules that contribute to this arrest, cDNA-representational difference analysis on BM stromal cells from young and adult rabbits showed that expression of Postn that encodes for the extracellular matrix protein periostin dramatically reduced with age. Postn-small interfering RNA OP9 cells lost their capacity to support B-cell development from rabbit or murine BM cells, and reexpression of periostin restored this potential, indicating an in vitro requirement for periostin in B lymphopoiesis.

A novel functional rabbit IL-7 isoform.

IL-7 is required for B cell development in mouse and is a key regulator of T cell development and peripheral T cell homeostasis in mouse and human. Recently, we found that IL-7 is expressed in rabbit bone marrow and in vitro, is required for differentiation of lymphoid progenitors to B and T lineage cells. Herein, we report the identification of a novel rabbit IL-7 isoform, IL-7II.