Quantum Dot Immunocytochemical Localization of Somatostatin inSomatostatinoma by Widefield Epifluorescence, Super-resolution Light, and ImmunoelectronMicroscopy

摘要

Quantum dot nanocrystal probes have been used for detection of somatostatin hormonein secretory granules of somatostatinoma tumor cells by immunofluorescence lightmicroscopy, super-resolution light microscopy, and immunoelectron microscopy.Immunostaining for all modalities was done using sections taken from an epoxyresin-embedded tissue specimen and a similar labeling protocol. This approach allowedassessment of labeling at light microscopy level before examination at super-resolutionand electron microscopy level and was a significant aid in interpretation. Etching ofultrathin sections with saturated sodium metaperiodate was a critical step presumably ableto retrieve some tissue antigenicity masked by processing in epoxy resin.Immunofluorescence microscopy of QD-immunolabeled sections showed somatostatin hormonelocalization in cytoplasmic granules. Some variable staining of tumor gland-likestructures appeared related to granule maturity and dispersal of granule contents withinthe tumor cell cytoplasm. Super-resolution light microscopy demonstrated localization ofsomatostatin within individual secretory granules to be heterogeneous, and this stainingpattern was confirmed by immunoelectron microscopy.