Transforming growth factor-beta up-regulates the gene expression of the human platelet-activating factor receptor in monocytic and B cell lines.

Platelet-activating factor is a potent phospholipid mediator which produces a wide range of biological responses by binding to a specific, high-affinity receptor on the target cell surface. Platelet-activating factor has been shown to have a very important pro-inflammatory role while the cytokine transforming growth factor-beta, also known for its diverse and potent effects, can act as both a pro- and anti-inflammatory agent. To ascertain whether transforming growth factor-beta could modulate the expression of the human platelet-activating factor receptor, different cell types were stimulated with this cytokine and the effect determined by Northern blot analysis and Ca2+ influx studies. The results demonstrate that transforming growth factor-beta induces the expression of the platelet-activating factor receptor in monocytic and B cell lines and indicate that transforming growth factor-beta could play a role in the modulation of the inflammatory response by up-regulating the expression of the platelet-activating factor receptor.