Normal intestinal mucosa contains abundant immunoglobulin A-secreting cells.
These cells are generated from B cells in gut-associated lymphoid tissues.
Dr Ulrich von Andrian and colleagues from Massachussetts showed that dendritic cells from gut-associated lymphoid tissues induce T cell-independent expression of immunoglobulin A (IgA).
In addition, the research team found that gut-associated lymphoid tissues induce gut-homing receptors on B cells.
|Vitamin A precursor deficient mice lack IgA-secreting cells in the small intestines|
The team observed that gut-associated lymphoid tissues-dendritic cell-derived retinoic acid alone conferred gut tropism.
However, this derivative could not promote immunoglobulin A secretion.
The team noted that retinoic acid synergized with gut-associated lymphoid tissues-dendritic cell-derived interleukin-5 or -6 to induce immunoglobulin A secretion.
Consequently, mice deficient in the retinoic acid precursor vitamin A lacked immunoglobulin A-secreting cells in the small intestine.
Dr von Andrian's team concludes, “Gut-associated lymphoid tissues-dendritic cell shape mucosal immunity by modulating B cell migration and effector activity through synergistically acting mediators.”