Mast cells are part of the immune system and characteristically contain histamine- and heparin-rich basophilic granules. While these cells are usually associated with allergy and anaphylaxis, they also promote wound healing and angiogenesis and confer protection against pathogens. The presence of these cells is sometimes indicative of a poor prognosis, especially in skin cancer, pancreatic cancer, and lymphoma. Toluidine blue staining of acid-fast granules is an established method for the identification and quantification of mast cells. Generating detailed information on the location of mast cells within tissues is problematic using this technique and often requires serial sections from adjacent tissue to be separately stained with hematoxylin and eosin (H&E). Staining serial sections is not always possible, particularly if the sample is very small or rare. In such cases, a method of simultaneously identifying and localizing mast cells in a tissue would be advantageous. Toluidine blue and H&E are not commonly combined because H&E includes repetitive washes in water, which may affect the efficacy of the aqueous-soluble toluidine blue. We have developed and tested a novel staining technique that integrates toluidine blue between hematoxylin and eosin in one simple procedure. This protocol works on both frozen and formalin-fixed, paraffin-embedded tissue and readily allows for the identification of purple-stained mast cells against a clean H&E background. This facilitates a more accurate localization and proper counting of mast cells in normal and affected tissue.
INTRODUCTION: Otitis media with effusion (OME) is an inflammation of the middle ear in which a collection of liquid is present in the middle-ear space while the tympanic membrane is intact. The association between adenoid inflammation and OME has long been noted but the exact mechanism is still much debated. We studied the role of adenoid mast cells in the causation of OME.
OBJECTIVE: To study the distribution and role of adenoid mast cells in the causation of OME.
METHODOLOGY: A cross-sectional, prospective study was carried out in the otorhinolaryngologic clinic, department of otorhinolaryngology (ORL), Science University of Malaysia, from June 1999 to September 2001. A total number of 50 cases were studied. Twenty-five of these patients underwent adenoidectomy, while another 25 patients underwent adenoidectomy and myringotomy with ventilation tube insertion. The adenoid specimens from all patients were examined for the number of adenoid mast cells present, using light microscopy and toluidine blue as the staining agent. The results were analysed using SPSS version 10.0 computer software.
RESULT: The population of adenoid mast cells in children with OME was significantly greater than that in children without OME (p=0.000).
CONCLUSION: The increased number of adenoid mast cells in patients with OME suggests that inflammation may play a role in this condition.
The association of mast cells with typical lesions of Kimura's disease was investigated by quantitative methods after immunohistochemical staining for Factor VIII-related antigen and counterstaining with toluidine blue. Formalin-fixed, paraffin-embedded, tissue sections from 9 confirmed cases of Kimura's disease were examined after staining to estimate mast cell and blood vessel densities by counting 100 random fields under oil immersion. There was a statistically significant increase of both mast cells and blood vessels in Kimura's disease (p<0.01) compared with normal skin and reactive lymph node controls. However, as far as the individual Kimura's disease lesion is concerned, there was generally no correlation between areas with mast cell increase and the degree of vascularity. Moreover, when lesions of less than 1 year's duration were compared with older lesions, there appeared to be a relative decrease in mast cells and a concomitant increase in vascularity in the latter. These results confirmed that mast cells are associated with Kimura's disease, and suggest that they may be involved in its early pathogenesis, although its possible role in angiogenesis may not be direct.