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

Background/Material and Methods: In 59 rat mandibular glands we investigate d the distribution of extracellular matrix proteins (EMP) in rat salivary g land tumors. The animals differed in age and pretreatment status (irradiati on versus no irradiation). For immunohistochemical analysis we used polyclo nal 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 basemen t membranes [(BM); laminin, collagen IV] and components of PM-associated st ructures (fibronectin, collagen III). Immunoreactivity was found in glandul ar tissue, in vascular walls, in nerve tissue and the interstitial connecti ve tissue. Various EMP showed different patterns. Significant differences w ere seen between irradiated and non-irradiated glands, often with generally stronger and more extended staining in the irradiated group. Thus, both ne rve tissue and excretory ducts (ECD) were in part strongly stained for AL, while LCD were intensely positive for AF. Conclusions: Preceding radiation has to be considered when interpreting salivary gland tissue, especially in tumor differentiation studies following irradiation.