Immunohistochemical detection of extracellular matrix proteins in the irradiated rat mandibular gland

UNLABELLED: BACKGROUND/MATERIAL AND METHODS: In 59 rat mandibular glands we investigated the distribution of extracellular matrix proteins (EMP) in rat salivary gland tumors. The animals differed in age and pretreatment status (irradiation versus no irradiation). For immunohistochemical analysis we used polyclonal EMP antibodies [anti-laminin (AL), anti-fibronectin (AF), anti-collagen-III (AC-III), anti-collagen-IV (AC-IV)].

RESULTS: The antibodies identified the different structures of the extracellular matrix: components of basement membranes [(BM); laminin, collagen IV] and components of BM-associated structures (fibronectin, collagen III). Immunoreactivity was found in glandular tissue, in vascular walls, in nerve tissue and the interstitial connective tissue. Various EMP showed different patterns. Significant differences were seen between irradiated and non-irradiated glands, often with generally stronger and more extended staining in the irradiated group. Thus, both nerve tissue and excretory ducts (ECD) were in part strongly stained for AL, while ECD were intensely positive for AF.

CONCLUSIONS: Preceding radiation has to be considered when interpreting salivary gland tissue, especially in tumor differentiation studies following irradiation.