Autocrine secretion of interferon γ negatively regulates homing of immature B cells

The mechanism by which immature B cells are sequestered from encountering foreign antigens present in lymph nodes or sites of inflammation, before their final maturation in the spleen, has not been elucidated. We show here that immature B cells fall to home to the lymph nodes. These cells can actively exclude themselves from antigen-enriched sites by downregulating their integrin-mediated adhesion to the extracellular matrix protein, fibronectin. This inhibition is mediated by interferon γ secretion. Perturbation of interferon γ activity in vivo leads to the homing of immature B cells to the lymph nodes. This is the first example of autocrine regulation of immune cell migration to sites of foreign antigen presentation.