The effects of preliminary proteolysis on the immunohistochemical and dye staining properties of elastic fibres

Lysozyme in abnormal dermal elastic fibers of cutaneous aging, solar elastosis and pseudoxanthoma elasticum

Staining of elastic fibres with antilysozyme antibodies has been noted previously. In this study, we examined the staining pattern of dermal elastic fibres in aging, solar elastosis, and lesional skin of pseudoxanthoma elasticum (PXE) using an antibody to lysozyme and the indirect-peroxidase technique. To assess the effects of aging, sun-protected skin (buttock) from a younger and an older group of patients was used. Sun damage was studied in skin specimens from varying sun-exposed body regions (trunk; head and neck). No staining was seen in sun-protected skin from younger individuals, whereas sun-protected skin from older persons had scattered positive fibres. Solar elastotic material was intensely positive and the number of positive fibres appeared to correlate with the amount of sun damage. Abnormal elastic fibres in PXE also stained positively, but less intensely, than fibres in solar elastosis. This study shows that changes in the elastic fibres due to degenerative processes or genetic factors results in altered antigenic expression of the fibres. This may be an epiphenomenon secondary to changes in proteoglycans, which are known to occur with solar elastosis and PXE, or may represent an adaptive phenomenon to maintain the elastic properties of the altered fibres or to decrease their antigenicity.

Elastosis in breast carcinoma: II. Association of protease inhibitors with immature elastic fibres

The elastosis of 11 invasive ductal and infiltrative lobular carcinomas of the breast was specifically immunostained for the plasma protease inhibitors alpha-1 antitrypsin, alpha-1 antichymotrypsin, alpha-2 macroglobulin, inter alpha trypsin inhibitor and C1 esterase inhibitor. None of these components was detected in the elastic fibres of normal ducts or blood vessels in the breast. The elastosis in breast carcinomas was also stained by Concanavalin A and Triticum vulgaris lectins. Such lectin staining probably represents binding to the microfibrillar component of elastic fibres, which is increased in immature elastic fibres, thus suggesting that the elastotic fibres of breast carcinoma are recently synthesised. It is suggested that the presence of protease inhibitors may influence the metabolism of elastic fibres, facilitating elastic fibre proliferation by the inhibition of elastinolytic enzymes.

Elastic fibres in normal and sun-damaged skin: an immunohistochemical study

Sun-exposed and sun-protected skin obtained at post mortem from the nape of the neck in 14 subjects was immunostained using antisera to elastin, lysozyme, amyloid P component, and the plasma protease inhibitors alpha-I antitrypsin, alpha-I antichymotrypsin and alpha-2 macroglobulin. Both the normal elastic fibres in sun-protected skin, and elastosis in sun-exposed skin were positively immunostained for elastin, lysozyme and amyloid P component. Collagen fibres were unstained. No immunostaining of normal elastic fibres or elastosis in the skin was obtained with antisera to alpha-I antitrypsin, alpha-I antichymotrypsin or alpha-2 macroglobulin. It was concluded that the elastosis in sun-exposed skin does contain elastic fibres. The absence of immunostaining for plasma protease inhibitors probably indicates that the elastic material is mature, and not newly-formed.

Elastosis in breast carcinoma: I. Immunohistochemical characterization of elastic fibres

Elastosis associated with invasive ductal and lobular carcinomas of the breast was examined by tinctorial and immunohistochemical staining methods, enzyme digestion, and electron microscopy. The elastotic material exhibited the tinctorial staining properties of elastic fibres, and the ultrastructural appearances were those of elastic fibres although there was a higher proportion of microfibrils than in normal mature elastic fibres. The elastosis was immunostained by antisera to human fetal elastin, lysozyme and amyloid P component, as in other sites where elastic fibres are found. These findings indicate that immunohistochemically intact elastic fibres are present in the elastosis of breast cancer. They also demonstrate that lysozyme and amyloid P component are co-distributed with elastic fibres in elastosis of breast carcinoma, as distinct components with different susceptibilities to enzyme digestion. The cellular origin of elastosis in breast carcinoma remains uncertain.

Metachromasia of 3-amino-9-ethylcarbazole (AEC) and its prevention in immunoperoxidase techniques

3-Amino-9-ethylcarbazole (AEC) used as chromogen in immunoperoxidase techniques normally has an intense, red colour. However, as an inconstant phenomenon, a pale yellowish-green reaction product severely impairing the evaluation can be observed. In order to circumvent this undesired effect, factors such as tissue fixative, proteolytic digestion, antibody concentrations and incubation time of the primary antibody were analyzed. The most important factor inducing a change in colour is probably the inadequately high local peroxidase concentration arising as the consequence of high amounts of bound primary antibody. This high enzyme concentration might cause metachromasia of AEC by producing the yellowish-green quinone-di-imine form of the substrate. As could be shown by spectrophotometry in test tube experiments, AEC metachromasia was proven to be enzyme dependent. Thus, the best way to trigger the local enzyme concentration on a tissue section to adequate levels appears to be the dilution of the primary antibody.

Lectin binding to elastic fibres and associated components during development of the human aorta

A panel of peroxidase-conjugated lectins was used to stain frozen sections of human foetal, neonatal, infant and adult aortae. Two main distinctive staining patterns were observed at the light microscope level, depending on the lectin employed. Lectins from Concanavalin A, Triticum vulgaris, Arachis hypogaea and Glycine max resulted in staining of the surfaces of aortic elastic lamellae and the interlamellar areas. With lectins from Dolichos biflorus and Bandeiraea simplicifolia staining was seen predominantly in the interlamellar areas. The findings indicate the presence of several different glycoconjugates at various sites within the aorta. In addition, there were alterations in the lectin binding affinities of the aortae that were dependent upon age. The findings are interpreted as indicating sequential changes in the composition of glycoprotein or proteoglycan moieties in the development of the human aorta.

Phenotypic expression of immune secretory function in focal pregnancy-like change of the human breast

Fibrocystic disease of the breast in middle-aged women characteristically shows focal epithelial lesions of a very varied nature. The functional immunohistochemical changes in such lesions have been little studied. Focal Pregnancy-like Change in the breast has a striking morphological similarity to the secretory breast lobules in pregnancy and in lactation. We show that the epithelial cells in all the lesions of Focal Pregnancy-like Change studied simultaneously express secretory component, Ig A and J chain in their cytoplasm. Additionally these epithelial cells, unlike those in resting breast lobules, contain lysozyme and lactoferrin. All these phenotypic immunohistochemical changes in Focal Pregnancy-like Change resemble the breast lobules of late pregnancy and lactation. Possibly, the very focality of Focal Pregnancy-like Change reflects a peculiar and local sensitivity of 'resting' breast lobules to unidentified hormonal stimulation.