Non-exposed Skin Research Articles

A Histological Study of the Evolution of Solar Urticaria

The histological evolution of solar simulator-induced lesions of solar urticaria was investigated in four severely affected white patients. A series of two to 32 minimal whealing doses of radiation, each much lower than the 24-hour minimal erythema dose, was administered to separate buttock sites. Biopsy specimens were obtained from the exposed areas at five minutes and two and 24 hours later, as well as from adjacent nonexposed skin. Lesions showed a statistically significant dose-dependent increase, predominantly perivascular, in upper dermal neutrophil and eosinophil numbers at five minutes and two hours, but not at 24 hours, and at higher radiation doses in mononuclear cell numbers by 24 hours. Nonirradiated patient skin and irradiated control subject skin was not similarly affected. These changes may be associated with the pathogenesis of solar urticaria.

Quantification of cutaneous oedema in patch test reactions by measurement of skin thickness with high-frequency pulsed ultrasound.

69 doubtful and positive patch test readings (?+21, +23, ++18, 7) in 15 contact dermatitis patients were studied by measurement of skin thickness as an expression of allergic oedema. Exposed skin was compared with a regional control. Skin thickness was measured by 15 MHz pulsed ultrasound (A-scan) to 0.1 mm accuracy. The ?+, +, ++, and reactions could be separated by measurements of absolute difference in thickness (p less than 0.001, p less than 0.001, p less than 0.02) between exposed and non-exposed skin; the mean increases were 0.14, 0.49, 0.93, and 1.37 mm. The ?+, +, and ++ reactions, but not the reactions, could also be separated by measurements of relative increase in skin thickness (p less than 0.001, p less than 0.001, n.s.); the mean increases were 7%, 25%, 50% and 55%. The normal thickness of the skin of the back was shown to have increased (p less than 0.02) in patients with reactions only. It is concluded that the high-frequency ultrasound method is suitable for quantification of doubtful and positive patch test reactions. The reactions are probably explained by the normal thick skin of the back, and they need no separate recording in patch testing. Standards of increase in skin thickness in doubtful and positive patch tests are defined: absolute increase (mm) was ?+ less than or equal to 0.2; +0.3-0.7; ++0.8-1.3 ( greater than or equal to 1.4); relative increases were ?+ less than 15%; +15-45%, ++ ( included) greater than 45%.

Immunofluorescence studies in progressive systemic sclerosis (scleroderma) and mixed connective tissue disease.

Immunofluorescence (IF) investigations of the skin were performed in thirty patients with progressive systemic sclerosis (scleroderma) and eight patients with mixed connective tissue disease (MCTD). The results show that speckled epidermal nuclear immunoglobulin deposition occurs not only in MCTD but also in true scleroderma. Granular IgM deposition at the dermo-epidermal junction of light-exposed skin was detected in both groups of patients, but six of eight MCTD patients also showed a granular IgM band in non-exposed skin. Antinuclear antibodies (ANA) were demonstrated in the sera of 96% and 100% of patients with scleroderma and MCTD respectively. The pattern of nuclear IF staining in scleroderma included dense fine speckles, large coarse speckles, threads, nucleolar and centromere staining. In MCTD, by contrast, the ANA staining pattern consisted of threads. The significance of ANA titres and immunological specificities for the in vivo reaction of serum ANA with epidermal nuclear antigens is discussed.

Diminished Immune Response in Sun-Damaged Skin

In previously sensitized volunteers, higher concentrations of 2,4-dinitrochlorobenzene were necessary to elicit positive patch test reactions on the sun-damaged skin of the neck than on the protected skin of the upper part of the back. This difference was not found in subjects without evidence of sun damage, and there was no difference between sun-damaged and nondamaged skin in response to a primary irritant. Responses to intradermally injected common antigens were also less intense in sun-damaged skin that in nonexposed skin. These findings suggest the existence of a local defect in cell-mediated immunity in skin altered by long-term sun exposure.

Effects of Aging and Chronic Sun Exposure on Melanocytes in Human Skin

Both aging and sun exposure have well-documented effects on the human melanocyte system. Paired biopsies of habitually exposed and nonexposed skin from adjacent anatomic sites were obtained from 8 donors aged 28 to 80 yr in order to study the combined effect of chronic actinic irradiation and chronologic aging. Density of dopa-positive melanocytes was roughly twofold higher in the exposed than in the nonexposed skin at all ages, suggesting an irreversible effect of sun exposure. Melanocyte density declined approximately 6 to 8% of the surviving population per decade in both sites. Dopa-positivity of individual melanocytes was consistently greater in the chronically exposed skin than in the nonexposed skin of the same subject and did not vary with age. These data strengthen and expand earlier observations of age-related melanocyte changes, and explain the apparent paradox of a generalized increase in pigmentation and simultaneous decrease in melanocyte density which frequently accompany advancing age. In addition, the present study suggests that the principal effect of chronic sun exposure on the human pigmentary system is not premature "aging" as currently recognized histologically, but rather activation and/or proliferation of the exposed melanocytes.

Actinic elastosis in black skin. A light- and electronmicroscopic study.

In 9 otherwise dermatologically normal South African Balck volunteers (1--72 years old), sunlight-exposed and non-exposed skin has been examined by light- and electronmicroscopy with special references to age-dependent and actinic alteration of dermal structures. Two 72 year old Blacks exhibited typical dermal elastosis: in 1 case to a marked extent and already detectable by lightmicroscopy, in the other case only to a mild degree. In contrast, only age-related elastic fibers were revealed in the lower dermis of sunlight-exposed skin and in all dermal layers of unexposed skin. These observations are contradictory to the general view that actinic elastosis does not occur in Blacks. The elastotic material is obviously a de-novo synthesized and secreted pathological product of chronically UV-altered fibroblasts.

Sulphated acid mucopolysaccharides in actinic elastosis.

SUMMARY.— The incorporation of 35SO4 into the acid mucopolysaccharides of skin in vitro has been used to study the metabolism of these substances in skin showing gross actinic elastosis, in exposed skin with less severe actinic changes, and in non-exposed skin. Whereas no alteration in the pattern of incorporation was demonstrated in the epidermis, elastotic dermis showed an increased incorporation of 35SO4, especially into the chondroitin-6-sulphate peak, as compared to the non-exposed dermis. The possible biological implications of these results are discussed, namely, (a) that treatment with weak alkali produces a greater yield of sulphated acid mucopolysaccharides from elastotic dermis than from normal dermis, or (b) that these substances are depolymerized in elastotic dermis with alteration in their elution positions on ion-exchange resin chromatography, or (c) that a real increase in turnover of chondroitin-6-sulphate exists when elastin is being laid down.