Role of protein phosphatases in the regulation of human mast cell and basophil function

Many extracellular stimuli mediate physiological change in target cells by altering the phosphorylation state of proteins. These alterations result fr om the dynamic interplay of protein kinases, which mediate phosphorylations , and protein phosphatases, which catalyse dephosphorylations. The antigen- mediated aggregation of high-affinity receptors for IgE on mast cells and b asophils triggers rapid changes in the phosphorylation of many proteins and culminates in the generation of inflammatory mediators involved in allergi c inflammatory diseases such as asthma. Although protein kinases have an es tablished role in this process, less is known about the involvement of prot ein phosphatases. This imbalance has been redressed in recent years by the availability of phosphatase inhibitors, such as okadaic acid, that facilita te investigations of the role of protein phosphatases in intact cells. Here we review a number of studies in which inhibitors of protein phosphatases have been used to shed light on the potential importance of these enzymes i n the regulation of human mast cell and human basophil function.