Mast cell mediators in the blood of patients with asthma

Mast cell activation occurs in allergic asthma and may play a role in a variety of nonallergic asthmatic states. The defined mast cell constituent histamine has been identified in blood of antigen-sensitive challenged asthma patients, while other mediators, whose cell of origin is not fully defined, accompany this amine in blood (Table 1). Due to technical difficulty in accurate assessment, the rapid metabolism of various constituents, and the need for biologic rather than chemical assay of some mediators, it is not yet possible to assess blood constituents for the unequivocal attribution of asthma to activation of a particular cell type. Likewise, the usefulness of blood studies in the prediction of the course of asthma or as serial measurements to define the severity of asthma remains limited. However, it is only with analysis of the appropriate biologic fluids, blood and/or bronchoalveolar lavage materials, that it will be possible to define which potential mediators are, in fact, present and active in asthma. Until such analysis is completed, it is not possible to assign a function in this disease to the numerous potent inflammatory mediators known to be active in in vitro or in vivo models of asthma.