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

The mechanism by which immature B cells are sequestered from encountering f oreign antigens present in lymph nodes or sites of inflammation, before the ir final maturation in the spleen, has not been elucidated. We show here th at immature B cells fail to home to the lymph nodes. These cells can active ly exclude themselves from antigen-enriched sites by downregulating their i ntegrin-mediated adhesion to the extracellular matrix protein, Fibronectin. This inhibition is mediated by interferon gamma secretion. Perturbation of interferon gamma activity in vivo leads to the homing of immature B cells to the lymph nodes. This is the first example of autocrine regulation of im mune cell migration to sites of foreign antigen presentation.