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.
A 61-year-old woman developed an angiosarcoma in the irradiated chest wall 2 1/2 and 4 years after mastectomy for a carcinoma of breast. The two sets of tumours were morphologically distinct and differed immunohistochemically. The short interval between post-operative irradiation and presentation of the angiosarcoma is unusual. The case is discussed in relation to others of allied type.
SUMMARY The technique of direct immunofluorescence has been applied to skin biopsy specimens fixed in formalin and embedded in paraffin wax. The results have been compared with those obtained by using snap-frozen biopsy specimens from the same patients. Trypsinisation of the dewaxed material allowed subsequent detection of immunoglobulins, complement, and fibrinogen. When compared to the fluorescence in the snap-frozen specimens, the staining in the paraffin sections was less bright and there was a higher rate of negatives. Even so, it was possible to establish the diagnosis in most cases of pemphigus, pemphigoid, and lupus erythematosus.
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.
Congo red is an acid-base indicator dye. In free solution the colour and absorption characteristics of Congo red depend not only on the pH but are also governed by the nature of the solvent environment. In tissue sections stained by Congo red, alteration of the pH and the use of non-aqueous solvents can effect differential colouring of the tissue components. Stained sections of unmodified and chemically substituted celluloses show that differential red or blue coloration reflects the acidic or basic character of the substrate. In stained tissue sections, secondary protein structure and porosity of the substrate may also influence their colour. The effect of non-aqueous solvents is probably to modify the ionization state of the dye-substrate complex, thus altering the colour of the Congo red. Such solvents may also change the aggregation or solvation states of the dye, with consequent modification in the colour of tissue components.
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