Mast cells and their mediators.

Mast cells (MC) are the most important cells in hypersensitivity reactions. Their functions in other pathological conditions are, however, not completely understood. At least two different MC subtypes have been isolated and it seems that due to environmental changes further differences in the morphology and functions of MC:s exist. The activation of MC:s can be both due to immunological and non-immunological factors and results in a release of different mediators and production of so called newly generated MC mediators. The functions following mediator release are complicated and several other inflammatory cells are involved in these reactions. Due to the more slowly effect of the newly generated mediators and the interaction of different cell types the effects of these reactions are often spread over a long time. It seems that MC:s may play an important part not only in hypersensitivity reactions but also in other pathological conditions as in inflammatory disorders.