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Notes: Summary Ultrastructural changes of Langerhans cells during spontaneous involution of plane warts were examined. In areas with activated macrophages and epidermal cell interaction, Langerhans cells showed signs of enhanced cellular activity with an increased number of Langerhans cell granules, as in contact dermatitis. The fine structure of Langerhans cell granules, however, was unusual in that the vesicular portion was surrounded internally by a membrane, and this portion frequently occurred independently taking the shape of a loop.

Notes: Summary Epidermal cysts are one of the most common tumors of the skin. Although asymptomatic ordinarily, they may sometimes become severely inflamed with massive invasion of polymorphonuclear leukocytes (PMN). We studied in vitro PMN chemotactic properties of the aqueous extract prepared from the horny material of epidermal cysts obtained from three patients. A crude aqueous extract of the horny content of the cysts showed PMN chemotactic activity, which, however, was less than that of a horny layer extract prepared from normal skin. Characterization of PMN chemotactic activity using a Sephadex G-75 column showed a peak in the low molecular weight fractions eluting between the vitamin B12 and phenol red markers, which corresponds with the peak of absorbance at 280 nm. The chemotactic substances withstood boiling and trypsin or protease digestion. Although the chemotactic activity was partially ether-extractable, the presence of leukotriene B4 was not demonstrated by radioimmunoassay. In addition to their own chemotactic activity, the horny extracts of epidermal cysts showed cytotaxigenic properties in the presence of fresh serum.

Notes: Abstract We counted the number of cell layers in the stratum corneum (SC) of normal skin taken from different anatomical locations of the body of 301 individuals of various ages. Frozen 6 μm thick sections were stained with a 1% aqueous solution of safranin and observed under a microscope after application of 2% KOH solution. There were great variations in the number of SC cell layers (mean ± SD) according to location and among different individuals. The smallest number was found in genital skin (6 ± 2), followed in order by skin of the face (9 ± 2), neck (10 ± 2), scalp (12 ± 2), trunk (13 ± 4), extremities (15 ± 4) and the palms and soles (47 ± 24). The heel showed the largest number (86 ± 36). No definite correlation was found between the number of corneocyte layers and sex of the individual, whereas there was a slight increase in the number of SC layers with age in the skin of the cheek and back, particularly in male individuals. Comparison of these data with those from functional assessments of the SC of the skin from various locations of healthy adults showed that transepidermal water loss, an indicator of SC barrier function, reflected the number of corneocyte cell layers. In contrast, high-frequency conductance, an indicator of the hydration state of the outer SC, did not seem to be under the influence simply of the number of SC cell layers.

Notes: Abstract Because of the presence of thick long hairs on the scalp, little information is available concerning the functional characteristics of the stratum corneum (SC) of scalp skin. We therefore conducted a functional study of the SC of lesional scalp skin of patients with alopecia areata and of patients with androgenetic alopecia. We compared the scalp with the cheek and the flexor surface of the forearm (volar forearm). The water barrier function of the scalp SC of both patient groups, in terms of transepidermal water loss (TEWL), was almost comparable to that of the volar forearm, and was far better than that of facial skin. However, hydration of the scalp skin surface, as evaluated by measurement of high-frequency conductance, was markedly higher than that of facial skin, and showed significantly higher values than the volar forearm. These characteristics seem to be dependent, at least to some extent, on the amount of sebum-derived skin surface lipids because these were abundant on the scalp skin. Moreover, removal of skin surface lipids led to a significant decrease in skin surface hydration. The superficial corneocytes, the size of which reflects the proliferative activity of the epidermis, were substantially smaller on the scalp than on the volar forearm but significantly larger than on the cheek. These findings suggest that the rate of turnover of the scalp epidermis is intermediate between that of the facial and volar forearm epidermis. We conclude that the SC of the scalp skin in humans is functionally distinct from that of the face and extremities.

Notes: Summary The complement system represents an important nonspecific skin defense mechanism. Its activation leads to the generation of products that not only help to maintain normal host defenses but also mediate inflammation and tissue injury. Proinflammatory products of complement include large fragments of C3 with opsonic and cell-stimulatory activities (C3b and C3bi), low molecular weight anaphylatoxins (C3a, C4a, and C5a), and membrane attack complex. Among them C5a or its degradation product C5a des Arg seems to be the most important mediator because it exerts a potent chemotactic effect on inflammatory cells. Intradermal administration of C5a anaphylatoxin induces skin changes quite similar to those observed in cutaneous hypersensititivy vasculitis that occurs through immune complex-mediated complement activation. Complement activation is involved in the pathogenesis of the inflammatory changes in autoimmune bullous dermatoses. In pemphigus complement activation by pemphigus antibody in the epidermis seems to be responsible for the development of characteristic inflammatory changes termed eosinophilic spongiosis. In bullous pemphigoid (BP) interaction of basement membrane zone antigen and BP antibody leads to complement activation that seems to be related to leukocytes lining the dermoepidermal junction. Resultant anaphylatoxins not only activate the infiltrating leukocytes but also induce mast cell degranulation which facilitates dermoepidermal separation and eosinophil infiltration. Similar complement activation seems to play a more direct role in the dermoepidermal separation noted in epidermolysis bullosa acquisita and herpes gestationis. Anaphylatoxin generation via the alternative pathway activation under ligth irradiation is implicated in the development of the immediate erythematous phototoxic reactions induced by such well-known chemicals as porphyrin, chlorthiazide, demethylchlortetracycline, and chlorpromazine. It is known that a direct exposure of the stratum corneum to living skin tissues induces intense infammatory changes. In vitro study demonstrated that the stratum corneum activates complement via the antibody-independent alternative pathway to generate C5a anaphylatoxin. Thus, accumulated horny material from the follicular wall seems to play a crucial role in the induction of pustules in inflammatory acne lesions and abscesses in ruptured epidermal cysts via the activation of the alternative complement pathway. Meanwhile, in search for the chemotactic factors responsible for the transepidermal leukocyte chemotaxis noted in psoriasis and related sterile pustular dermatoses, we have detected the presence of unique chemotactic peptides in the scale extracts of lesional skin. Later studies identified the presence of C5a des Arg and IL-8 in this peptide fraction. The alternative complement pathway has been speculted for the complement activation at the subcorneal portion of the psoriatic epidermis by further immunological studies. Similar properties to activate the alternative complement pathway have been noted in various pathogenic fungi that induce inflammatory skin lesions. Generation of C5a anaphylatoxin beneath the fungus-laden stratum corneum seems to be responsible for the characteristic subcorneal pustule formation in superficial infections such as cutaneous candidiasis and dermatophytosis, whereas that around fungal spores in the dermis is presumed to play a role in the induction of mixed cell granuloma characterized by a dense neutrophil infiltration as noted in sporotrichosis and chromomycosis. AlthoughPityrosporum ovale constitutes ordinary skin microflora in seborrheic areas, its properties which activate complement via the alternative pathway are implicated in the pathogenesis of dandruff and seborrheic dermatitis, in which transepidermal neutrophil chemotaxis as noted in psoriasis is observed histopathologically.