Phase Contrast Microscopy with Modified Hansel's Staining: Mast Cell Identification and Activity-Related Changes in Cell Membrane Refractivity in Allergic Nasal Smears

Abstract

Background A new technique called phase contrast microscopy with modified Hansel's staining (used with bright field microscopy) was developed to identify mast cells (MCs) and granulocytes (eosinophil/neutrophil/basophil [E/N/B]). Methods Nasal scratching smears from 618 patients with Japanese cedar pollinosis were examined using this new technique. Results This technique permitted accurate morphological identification. MCs can be discriminated from E/N/Bs. The surface of the cell membrane appeared as low refractile (lr), moderately refractile (mr), or high refractile (hr). This was caused by the light, which is not related to the phase difference, but rather originated from the difference in the refraction of the direct light. In specimens from the onset stage (i.e., 1–3 days after onset), lr-MC and mr/hr-E/N/B were dominant. In specimens from the early stage (i.e., 4–7 days after onset), lr-E/N/B significantly increased in number. Conclusion The phospholipid bilayers of the cell membrane exhibit a phase transition after the onset, and phase refractivity of the cell membrane is closely related to the activity of the cell. This indicates that in the onset stage, MCs are already activated, whereas most of the E/N/Bs are not. In contrast, the latter cell types become activated subsequently in the early stage.