A New Image Analysis Method Based on Morphometric and Fractal Parameters for Rapid Evaluation of In Situ Mammalian Mast Cell Status.

Apart from their effector functions in allergic disorders, tissue-resident mast cells (MC) are gaining recognition as initiators of inflammatory events through their distinctive ability to secrete many bioactive molecules harbored in cytoplasmic granules. Activation triggers mediator release through a regulated exocytosis named degranulation. MC activation is still substantiated by measuring systemic levels of MC-restricted mediators. However, identifying the anatomical location of MC activation is valuable for disease diagnosis. We designed a computer-assisted morphometric method based on image analysis of methylene blue (MB)-stained normal mouse skin tissue sections that quantitates actual in situ MC activation status. We reasoned MC cytoplasm could be viewed as an object featuring unique relative mass values based on activation status. Integrated optical density and area (A) ratios were significantly different between intact and degranulated MC (p<0.001). The examination of fractal characteristics is of translational diagnostic/prognostic value in cancer and readily applied to quantify cytoskeleton morphology and vasculature. Fractal dimension (D), a measure of their comparative space filling capacity and structural density, also differed significantly between intact and degranulated MC (p<0.001). Morphometric analysis provides a reliable and reproducible method for in situ quantification of MC activation status.