Early stages of B cells development are dependent on bone marrow stromal cells and achieve maturity in peripheral lymphoid organs
Stromal cells:
(1) Provide specific contacts with B cell progenitors: Adhesion molecule VCAM-1 and CAMs on stromaè promote the binding of the receptor tyrosine kinase Kit (CD117) on B cell to stem-cell factor (SCF: stromal membrane bound cytokine) è induces proliferation (2) Provide soluble factors that control lymphocyte proliferation and further development : IL7 to IL7 receptor (in mice), chemokine CXCL12, steroid hormones (limit production of B cells)