The in vivo effects of lymphokines on mitotic activity and keratinization in guinea pig epidermis

Mitotic Langerhans cell as a possible sign of activation in ichthyosis

The fine structure of Langerhans cells (LC) in four rare types of ichthyosis, namely recessive ichthyosis congenita type II, III and IV and ichthyosis hystrix Curth-Macklin was examined. Signs of LC activation were observed in eight of 21 patients. In IC type IV, the rare occurrence of a mitotic LC was observed. It is possible that LCs are secondarily activated in keratinization disorders.

Effect of systemic interleukin-3 administration on epithelial cell proliferation in mouse intestine

The effect of interleukin-3 (IL-3) on the crypt cell production rate (CCPR) in the intestine of mice was studied using a stathmokinetic technique combined with crypt microdissection. Interleukin-3 (0.71 micrograms/injection) was administered subcutaneously (s.c.) as two injections per day for 7 successive days and small mucosal pieces (duodenum, jejunum, ileum and colon) removed at necropsy were organ cultured in the presence of the metaphase arrest agent vincristine sulfate for two hours. The number of metaphases was enumerated in dissected crypts and CCPR calculated. The results demonstrated that the CCPR was significantly increased in all mucosal segments in the IL-3 treated animals compared to saline injected controls. These results suggest that the growth promoting properties of IL-3 are not restricted to hematopoietic cells when used in vivo and may directly or indirectly increase epithelial cell turnover in gut mucosa.

Differential effects of structurally unrelated chemical irritants on the density of proliferating keratinocytes in 48 h patch test reactions

Alterations in the proliferative capacity of human epidermis following topical exposure to structurally unrelated chemical irritants were investigated, with the aim of improving our understanding of the cellular changes that take place during the development of irritant contact dermatitis (ICD). Healthy volunteers were patch tested for 48 h with the following six irritants and their appropriate vehicle and occlusion controls: 5% sodium lauryl sulphate (SLS), 0.5% benzalkonium chloride, 80% nonanoic acid (NAA), 0.02% dithranol, 0.8% croton oil, and 100% propylene glycol (PG). After the degree of inflammation induced was visually graded, biopsy samples were removed and the dividing keratinocytes were identified immunocytochemically by using the monoclonal antibody Ki-67, with quantification being performed on the basis of the number of positive cells/100 basal keratinocytes. Statistically significant increases in the density of proliferating cells occurred in the reactions to SLS, NAA, and PG, whereas, in contrast, dithranol caused a marked decrease in the number of dividing keratinocytes. Overall, the density of proliferating keratinocytes did not show a linear relationship with the visually assessed intensity of inflammation, indicating that the changes observed were related to the chemical nature of the individual irritants and their specific biochemical interactions with the keratinocytes, rather than being the consequence of a generalized inflammatory response. Differential release of epidermal cytokines and mediators by the six irritants may account for these varying states of keratinocyte proliferation. Application of the Spearman rank coefficient of correlation revealed that the changes in mitotic activity of keratinocytes were unrelated either to the total density of leukocytes infiltrating the epidermis and dermis, or to the individual densities of the major phenotypic classes of inflammatory cells present. This makes it unlikely that the localized release of cytokines by infiltrating leukocytes is, by itself, the primary factor in the alteration in epidermal cell kinetics seen in ICD. Our results provide a further demonstration of the diverse actions of different chemical irritants on human skin and emphasize the need to regard ICD as a heterogeneous disorder.

UM4D4+ (CDw60) T cells are compartmentalized into psoriatic skin and release lymphokines that induce a keratinocyte phenotype expressed in psoriatic lesions

UM4D4 (CDw60), the surface molecule of a novel antigen-independent T-cell activation pathway, was found to be highly expressed on lesional psoriatic T cells. To examine whether UM4D4 represents a T-cell activation pathway for psoriatic T cells, a T-cell line was initiated from an acute skin lesion and cloned by limiting dilution. Clonality was verified by analysis of T-cell receptor gene rearrangement. All T-cell clones tested, whether CD4+2H4+CD8-, CD4+2H4-CD8-, or CD4-CD8+CD11b-, expressed UM4D4 and were activated by the monoclonal antibody anti-UM4D4. Lesional psoriatic T-cell clones were heterogeneous in the degree of anti-UM4D4-induced proliferation and in their production of IL-2 and gamma-interferon. Lymphokines released by anti-UM4D4 activation were capable of inducing ICAM-1 and HLA-DR expression on cultured normal keratinocytes. Thus, the high expression of UM4D4 on T-cells in psoriatic skin provides an alternative mechanism for T-cell activation that may be operative in the psoriatic lesional milieu. Indeed, activation of lesional T-cells through the UM4D4 molecule resulted in release of lymphokines that directly induced keratinocytes to express a phenotype displayed in psoriatic skin lesions.

In vivo effects of Candida albicans products on rat oral epithelium

Candida albicans has been associated with epithelial hyperplasia in some diseases of oral mucosa and skin but its etiologic role in these lesions is poorly understood. To test its ability to induce epithelial proliferation, the invasive hyphal form was cultured for 5 h and 23 h in chemically defined medium and yeast-free culture supernatants were injected below the buccal epithelium of young adult Sprague Dawley rats. The mitotic activity was assessed using the metaphase arrest technique 11 h and 31 h after supernatant injection. There was a significant increase in epithelial mitotic activity 31 h after injection with 5 h culture supernatants compared to control media indicating that the supernatants have an effect on epithelial cells, possibly by direct action on them.

Effectiveness of cyclosporine treatment in severe psoriasis: a clinical and immunologic study

The effectiveness of low doses of cyclosporine (3 to 5 mg/kg/day) for short-term treatment in 13 patients with severe psoriasis was studied. The psoriasis cleared in 12 of 13 patients within 3 to 4 weeks of treatment, and there was appreciable improvement in the thirteenth patient. No major side effects were observed: two patients showed biochemical evidence of slight transient renal dysfunction and three others had cutaneous infections (two viral and one mycotic). An immunohistologic study showed that the psoriatic plaques contained an infiltrate composed mainly of activated helper T lymphocytes. After 15 days of cyclosporine treatment, CD4+ cells were significantly fewer in the epidermis and dermis, and Langerhans cells were more regularly distributed in the epidermis. Our studies of neutrophil chemotaxis showed that it is not significantly influenced by cyclosporine in vitro but is decreased in vivo.

Psoriatic epidermal cells demonstrate increased numbers and function of non-Langerhans antigen-presenting cells

The recent findings that the immunosuppressant cyclosporine A (CsA) improves psoriasis raises the possibility that cellular immune processes play a major role in the pathogenesis of psoriasis. We therefore investigated the phenotype and function of cells within psoriatic epidermis that can play a role in cellular immunologic reactivity. Double fluorescence microscopic studies with monoclonal antibodies of epidermal cells in suspension (EC) and of histologic sections demonstrated that involved psoriatic skin contained a significantly increased number of non-Langerhans cell T6-DR+ EC (4.9 + 2.1%) relative to uninvolved (0.3 +/- 0.1%), p less than 0.01. This non-Langerhans cell population was comprised of DR+ monocytes, DR+ activated T lymphocytes, a few DR+RFD1+ antigen-presenting cells (APC), and DR+ keratinocytes. Langerhans cell (LC) levels in EC suspension were not different between involved and uninvolved psoriatic epidermis. Functional studies demonstrated that involved psoriatic epidermal cells had an increased capacity to induce T-cell activation and proliferation relative to uninvolved EC (p less than 0.04). This increased APC activity was due to the non-LC T6-DR+HLe1+ APC population and not to DR+ keratinocytes. These results demonstrate that involved psoriatic epidermal cells contain both an increased number and function of antigen-presenting cells. The pathogenetic mechanisms in psoriasis may be related to ongoing cellular immune responses in the skin, and the effect of CsA may be mediated through a suppressive effect on the enhanced antigen-presenting cell activity.

Patterns of keratin-expression in rests of Malassez and periapical lesions

Using immunocytochemistry and a panel of monoclonal antibodies directed against various keratin polypeptides we examined specimens of normal periodontal ligament, periapical granulomas and inflammatory dental cysts. Epithelial elements with the appearance of rests of Malassez were identified in 6 specimens of normal periodontium and 10 periapical granulomas. Altered epithelium was present in 16 periapical granulomas and a lining epithelium in 10 inflammatory dental cysts. The patterns of binding of antibodies by these epithelia indicated that (a) keratin 19 was expressed by all epithelia, and (b) rests of Malassez also expressed keratin 5 but not large amounts of other keratins and (c) epithelial proliferation in periapical lesions was associated with increased expression of keratin 14, a marker of stratifying epithelia, new expression of keratins 4 and 13, differentiation markers for non-cornifying epithelia and variable, low levels of keratins 8 and 18, markers of simple epithelia. Proliferation of the epithelial rests of Malassez to form the lining of inflammatory dental cysts thus appears to be associated with a change from an unusual epithelial phenotype to that of a stratified non-cornifying epithelium in which some simple epithelial keratins are coexpressed.

Autocrine growth stimulation of human keratinocytes by epidermal cell-derived thymocyte-activating factor: implications for skin aging

The monocyte-derived cytokine interleukin-1 (IL-1) has growth-promoting activity for a variety of cell types, including lymphocytes and fibroblasts. We have previously shown that the epidermal cell-derived thymocyte-activating factor (ETAF) strongly resembles IL-1 in terms of biological, biochemical, and molecular biological properties. Because some lymphokines are known ot alter epidermal cell growth and differentiation and because cultured epidermal keratinocytes are capable of autocrine growth stimulation in vitro through "conditioning" of their culture medium, we sought to evaluate the effect of ETAF on keratinocyte growth. While there was marked donor variability in the responsiveness of keratinocytes to ETAF, partially purified preparations of ETAF showed substantial ability to stimulate the growth of keratinocytes, particularly those of newborn donors. In addition, in conditioned media there appeared to be activities distinct from ETAF that also promoted keratinocyte growth. Keratinocytes in serum-free medium secreted large amounts of ETAF, as reported previously, and keratinocyte cultures derived from newborn donors secreted significantly more than did those derived from adult donors. These results are consistent with an autocrine growth regulatory role of ETAF in human epidermis and with an age-associated loss of this phenomenon.

Immunocytochemical examination of immune cells in periapical granulomata and odontogenic cysts

Monoclonal antibodies (mAbs) were used to determine the presence and distribution of immune cells including lymphocytes, macrophages and Langerhans cells, in normal periodontal ligament, periapical granulomata, periapical cysts and dental developmental cysts. Isolated T-lymphocytes, but not B-lymphocytes, were detected in specimens of non-inflamed periodontal ligament. Increased numbers of T and B lymphocytes were found in all of the lesions examined. Monocytes/macrophages were associated with most periapical granulomata, dental developmental cysts and all periapical cysts. Langerhans cells, intraepithelial lymphocytes, and monocytes/macrophages were not detected in the rests of Malassez but were found in some epithelia within periapical granulomata and in most epithelial linings of odontogenic cysts. Increased numbers of immune cells were seen around proliferative epithelia and adjacent to the epithelial linings of cysts. Epithelium, particularly that of odontogenic cysts, showed positive reactions for HLA-Dr, lysozyme and for alpha-1 antitrypsin. The presence of immune cells in periapical granulomata and odontogenic cysts, suggests that cell-mediated and humoral immunoreactions occur in these lesions and may be associated with the epithelial proliferation within the periapical lesions.

Relationship between macrophage infiltration and epidermopoiesis in delayed-type hypersensitivity

The relationship between epidermopoiesis and macrophage infiltration was studied in delayed-type hypersensitivity (DTH) skin lesions in guinea pigs that had been sensitized with heat-killed tubercle bacilli or bovine serum albumin (BSA). Macrophages were identified with acid-phosphatase and nonspecific esterase stains, and the epidermal proliferative response was studied at DTH challenge sites by autoradiography. The number of macrophages in the sensitized animals was higher than that in the nonsensitized animals 48-72 h following challenge injections, when labelling indices were also elevated in the former group. Soluble factor(s) from cultured macrophages transiently enhanced the DNA synthesis of epidermal cells in cultures and in the sites injected with the factor(s). These results suggest that macrophages retained in the DTH lesion may play a role in an acceleration of epidermal proliferation, thus leading to acanthosis and lichenification.

Lymphokine mediated production of an epidermal cell proliferation factor by cultured murine bone marrow cells

The effect of cultured bone marrow cell supernatant (BMS) was studied on the proliferative response of cells of the transformed murine epidermal cell line Pam 212. Elevated DNA synthesis was found in Pam 212 cells cultured with BMS from bone marrow cells grown in spleen cell conditioned medium with concanavalin A (ConA). Pam cell proliferative activity was related to the histamine content in the culture supernatant. Neither spleen cell conditioned medium with IL1, IL2, or IL3 activity, nor ConA alone, showed any effect on Pam cell growth. A soluble mediator from the cultured bone marrow cells with mast cell characteristics was thought to be responsible for the stimulation of Pam cell growth, and Con A appeared to be a prerequisite for generation of this factor by the bone marrow cells.

The effects of cyclosporin A on T lymphocyte and dendritic cell sub-populations in psoriasis

Sequential skin biopsies from six patients with severe psoriasis were studied during treatment with cyclosporin. Four of the patients cleared completely and the remaining two showed a marked improvement. A subset of dendritic cells, HLA-DR+ but lacking the T6 antigen characteristically expressed by Langerhans cells (DR+ 6-), was observed in lesional epidermis. They disappeared during treatment, before clinical improvement was apparent and at a rate which correlated with clearance of psoriasis. These cells were not found in normal or uninvolved psoriatic epidermis and their number in lesional skin appeared to be related to the clinical severity of the disease. Total numbers of CD4 and CD8, and HLA-DR+ CD8 T cells were substantially reduced in both epidermis and dermis prior to clinical improvement. In contrast, there was generally no decrease in the number of HLA-DR+ CD4 T cells in the epidermis during resolution, whereas these cells were reduced by an average of 68% in the dermis. The beneficial effects of cyclosporin in psoriasis further support the hypothesis that T cells play a central role in the pathogenesis of psoriasis. The cellular changes observed in the skin during cyclosporin treatment may help to elucidate the effects of this drug on immunoregulatory mechanisms in man.

HLA-DR antigen expression on keratinocytes in highly inflamed parts of psoriatic lesions

We have investigated the immunoperoxidase staining pattern in the epidermis and dermal infiltrates of highly inflamed portions of psoriatic lesions, selecting for biopsy early pinpoint lesions or margins of active plaque lesions. We found positive intercellular staining for HLA-DR antigens in localized areas of the epidermis in about half of the patients tested. In contrast, OKT6 antigen was found only on the dendritic cells in the epidermis and dermis in all cases. These findings support the hypothesis that an active cellular immune reaction involving the epidermis, possibly associated with the expression of HLA-DR antigens on keratinocytes, occurs in the highly inflamed areas of psoriatic lesions, particularly in early pinpoint lesions or at the edges of spreading plaque lesions.

Psoriasis: a disease of abnormal Keratinocyte proliferation induced by T lymphocytes

Psoriasis affects 2% of the population in Western countries. Its aetiology and pathogenesis remain unknown but suggestions include abnormalities of blood vessels, neural components, epidermal cell cycle time or maturation of keratinocytes. More recently autoimmune reactions have been implicated involving stratum corneum antibodies(1) and antibodies to nuclei of basal epidermal cells(2). However, there is no convincing evidence that any of these abnormalities are of primary nature. In this article, Helgi Valdimarsson and his colleagues propose that the process leading to psoriatic lesions is triggered by T lymphocytes within the epidermal compartment. They envisage that psoratic lesions erupt where epidermal influx of antigen-carrying Langerhans cells and helper T lymphocytes overrides the normal epidermal suppressor mechanism.

Stress, symmetry, and psoriasis: possible role of neuropeptides

The role of stress as a triggering factor in the exacerbation of psoriasis and the clinically symmetric distribution of psoriatic plaques suggested a possible role for neuropeptides in the etiopathogenesis of psoriasis. Several observations by other investigators involving substance P suggested to us a possible role for substance P as a modulator of the inflammatory response in psoriasis. A hypothesis for the role of substance P that would account for the temporal onset with stress, the clinical symmetry of lesions, and the histopathologic features of psoriasis is presented.

Changes in the rate of epithelial proliferation of rat oral mucosa in response to acute inflammation induced by turpentine

Inflammatory lesions were produced in the buccal mucosa by a subepithelial injection of turpentine; animals were killed 24 h later, 1 h after an intravenous injection of tritiated thymidine ( [3H]-Tdr). Control rats were given [3H]-Tdr but no turpentine. Lesions comprised a turpentine pool surrounded by a dense layer of inflammatory cells, beyond which the tissues were more diffusely inflamed. The labelling index (L.I.) for mitotic activity in overlying epithelium was determined in a region (C) close to the layer of dense infiltration and in a region (D) more distant. The L.I. in region D was over four times greater than in region C, and nearly four times greater than that of the contralateral, uninjected cheek. The L.I. in the uninjected cheek was significantly lower than that in controls, which may indicate a systemic depression of proliferative activity in the experimental animals, probably due to stress. Thus mild inflammatory injury stimulates epithelial proliferation, whereas more severe inflammation depresses it, perhaps due to more extensive progenitor-cell damage.

Subpopulations of mononuclear cells in microscopic lesions of psoriatic patients. Selective accumulation of suppressor/cytotoxic T cells in epidermis during the evolution of the lesion

The age of microscopic lesions in psoriatic subjects was assessed from the stacking characteristics in the horny layer and related to type and density (cells/tissue volume) of mononuclear cells in the epidermis and the dermis determined by immunoperoxidase methods using monoclonal antibodies. Pan T cells (Lyt-2+, Lyt-3+, Leu-4+, OKT3+), T helper cells (Leu-3a+, OKT4+), T suppressor/cytotoxic cells (Leu-2a+, OKT8+), Ia+ cells and monocytes (OKM2+, BRL alpha mono+) were determined in epidermis and dermis. The psoriatic lesion was divided into regions underneath a parakeratotic and an orthohyperkeratotic/hypergranular portion of the horny layer and contrasted with perilesional and uninvolved psoriatic skin as well as with healthy skin. In the various regions and skin layers, the cell density was highest in parakeratosis and decreased toward normality with decreasing histologic abnormality. The relation between epidermal and dermal cell densities of the T-cell subsets was modified in the involved psoriatic skin with a selective preponderance of T suppressor/cytotoxic cells in the epidermis. The accumulation was present in the youngest lesion found (3 days) and cell densities were unchanged in older lesions. The findings suggests that the altered relationship in the subsets of T cells has an important role during the induction and progress of the psoriatic process in the skin.

Epidermal T lymphocytes and HLA-DR expression in psoriasis

Double staining immunofluorescent techniques and monoclonal antibodies were used to study the numbers, distribution, HLA-DR expression and relationship of T-cell subpopulations and dendritic cells in psoriatic skin. In the dermis there was a definite increase in both T helper and T suppressor cells in uninvolved skin of psoriatic patients, and the appearance of clinical lesions was not associated with any detectable change in the numbers of these cells in the dermis. In contrast, eruption of skin lesions was associated with an increase in the numbers of epidermal HLA-DR+ dendritic cells and also with epidermal influx and activation of T helper cells, while resolution of lesions coincided with increased epidermal entry and activation of T suppressor cells. Both the T helper and T suppressor cells were preferentially found adjacent to epidermal dendritic cells. These findings suggest that the clinical activity of psoriasis may be dependent upon the interaction of T helper and suppressor cells with antigen-presenting cells in the epidermis.

The thymus dependency of acquired resistance to Trichophyton mentagrophytes dermatophytosis in rats

Congenitally athymic "nude" (RNU/RNU) rats and euthymic (+/RNU) rats were cutaneously inoculated with Trichophyton mentagrophytes. Dermatophytosis, as evidenced by erythema and scaling, was observed in both athymic and euthymic rats by day 7 postinfection. Macroscopic lesions in +/RNU rats became intensely erythematous (climax days 10-14), were limited in spread and alopecia (days 16-20), and healed with hair regrowth by day 35. In nude rats, however, erythema peaked early (days 8-10) and a persistent, mild erythema and scaling spread over the animals' backs. Viable T. mentagrophytes was cultured from the skin of all infected nude rats for the duration of each experiment (90 days), while +/RNU rats became culture-negative by day 35. Following clearance of primary lesions, +/RNU rats manifest a delayed-type hypersensitivity skin test response to soluble trichophytin and an accelerated cutaneous inflammation and enhanced resistance to reinfection. Although T. mentagrophytes primarily invaded the keratinized layers of the epidermis in both nude and +/RNU rats, hyphae and arthrospores were also observed within the nucleated layers of the internal root sheath of hair follicles. Our observations are consistent with the hypothesis that thymus-dependent cell-mediated immunity is required to limit cutaneous spread and terminate cutaneous T. mentagrophytes infection. This acquired immunity against T. mentagrophytes in +/RNU rats was characterized histologically by: (1) an intense inflammatory migration of lymphocytes, monocytes, and macrophages into the epidermis, dermis, and follicular epithelium; (2) hyperplasia of the epidermis and follicular epithelium; and (3) elimination of arthrospores and hyphae from T. mentagrophytes-infected skin.