Expression of Ia antigens on Langerhans cells in mice, guinea pigs, and man

Tacrolimus Reverses UVB Irradiation-Induced Epidermal Langerhans Cell Reduction by Inhibiting TNF-α Secretion in Keratinocytes via Regulation of NF-κB/p65

Background: Topical calcineurin inhibitors including tacrolimus and pimecrolimus are used in the treatment of many inflammatory skin diseases mainly via blocking T-cell proliferation. Our previous studies found that pimecrolimus 1% cream could reverse high-dose ultraviolet B (UVB) irradiation-induced epidermal Langerhans cell (LC) reduction via inhibition of LC migration. We conducted this study to investigate the effects of topical tacrolimus 0.03% ointment on high-dose UVB-irradiated human epidermal LCs. Methods: Twenty fresh human foreskin tissues were randomly divided into four groups as follows: Control, Tacrolimus (0.03%), UVB (180 mJ/cm2), and UVB (180 mJ/cm2) + Tacrolimus (0.03%). Four time points were set as follows: 0, 18, 24, and 48 h. We collected culture medium and tissues at each time point. The percentage of CD1a+ cells in the medium was detected by means of flow cytometry. Each tissue was prepared for immunohistochemistry, real-time quantitative PCR, and western blot. HaCaT cells were cultured and divided into four groups: Control, Tacrolimus (1 μg/ml), UVB (30 mJ/cm2), and UVB (30 mJ/cm2) + Tacrolimus (1 μg/ml). The cells were incubated for 24 h and prepared for real-time quantitative PCR and western blot. Results: Topical tacrolimus significantly reversed high-dose UVB irradiation-induced epidermal LC reduction and CD1a+ cell increment in culture medium. Tacrolimus significantly inhibited UVB irradiation-induced tumor necrosis factor-α (TNF-α) and nuclear factor kappa B (NF-κB)/p65 mRNA and protein expression in HaCaT cells. Tacrolimus also significantly inhibited high-dose UVB irradiation-induced TNF-α expression in cultured tissues. Finally, TNF-α antagonist (recombinant human TNF-α receptor II: IgG Fc fusion protein) could significantly reverse UVB irradiation-induced epidermal LC reduction. Conclusion: Topical tacrolimus 0.03% could reverse UVB irradiation-induced epidermal LC reduction by inhibiting TNF-α secretion in keratinocytes via regulation of NF-κB/p65.

Topical pimecrolimus inhibits high-dose UVB irradiation-induced epidermal Langerhans cell migration, via regulation of TNF-α and E-cadherin

Background

Topical pimecrolimus has been shown to reverse epidermal CD1a⁺ Langerhans cell reduction induced by high-dose ultraviolet (UV)B irradiation, but the mechanism is still unclear. This study aimed to investigate the possible mechanism of the effect of pimecrolimus on high-dose UVB-irradiated epidermal Langerhans cells.

Methods

Forty human foreskin tissues were divided into four groups: control; pimecrolimus-only; UVB-only; and UVB + pimecrolimus. All tissues were cultured, and each tissue was cut into four pieces, corresponding to four time points (0 hours, 18 hours, 24 hours, and 48 hours). We collected the tissues and culture medium at each time point. The percentage of CD1a⁺ cells in medium was detected by flow cytometry. The tissues were detected for messenger (m)RNA and protein expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and E-cadherin, by reverse-transcription polymerase chain reaction (PCR) and Western blot.

Results

At 18 hours, 24 hours, and 48 hours, the CD1a⁺ cells in the culture medium of the UVB-only group and the UVB + pimecrolimus group were significantly more than in the control group, while the CD1a⁺ cells of the UVB + pimecrolimus group was less than of the UVB-only group. For both the UVB-only group and UVB + pimecrolimus group, TNF-α expression (by both reverse-transcription PCR and Western blot) of the tissues was clearly higher and E-cadherin expression was significantly lower compared with the control group, at 18 hours, 24 hours, and 48 hours. For the UVB + pimecrolimus group, TNF-α was clearly lower and E-cadherin was significantly higher compared with the UVB-only group.

Conclusion

Topical pimecrolimus inhibited epidermal Langerhans cell migration induced by high-dose UVB irradiation, via regulation of TNF-α and E-cadherin.

Effects of topical pimecrolimus 1% on high-dose ultraviolet B-irradiated epidermal Langerhans cells

Some studies reported no changes in the number of epidermal Langerhans cells (LC) that were observed in mice treated with pimecrolimus, and low-dose stimulated solar radiation (once)-induced changers in LC are minimally affected by pimecrolimus. This study is to investigate the effects of topical pimecrolimus 1% on high-dose ultraviolet B (UVB)-irradiated epidermal LC. Forty human foreskin tissues were randomly divided into 4 groups of 10 tissues each: Group A, control; Group B, pimecrolimus 1% (once)-only; Group C, 180 mJ/cm(2) UVB (once)-only; Group D, UVB+pimecrolimus. Each tissue was cut into 4 pieces corresponding to 4 time points. All the tissues were cultured at 37 °C. After being treated, the tissues were collected respectively and processed for immunohistochemical staining and immunofluorescence staining. For UVB-only group, epidermal CD1a(+) LC number at 18h decreased from 39.6 ± 8.30 to 22.3 ± 2.26/5 high magnification, compared to CD1a(+) LC number at 0 h (P<0.01). The CD1a(+) LC number of UVB-only group was significantly less than other groups at 18 h, 24h and 48 h (P<0.05, respectively). Similar results were obtained with immunofluorescence staining for CD 1a and immunohistochemical staining for Langerin. The numbers of epidermal HLA-DR(+) LC had no significant differences among all groups at different time points. Our study found a single 180 mJ/cm(2) UVB irradiation significantly reduced epidermal LC numbers at 18 h, 24h and 48 h, however, topical pimecrolimus could reverse these changes. UVB plus pimecrolimus treatment did not affect human LC maturation.

Effects of pimecrolimus versus triamcinolone on Langerhans cells after UV exposure

BACKGROUND/PURPOSE

Pimecrolimus is a topical immunomodulator for atopic dermatitis. Concerns regarding malignancy risk resulted in its black box warning in 2006. The purpose of this study is to determine the effects of pimecrolimus on Langerhans cells (LC), mediators of the cutaneous immunity UV-irradiated skin.

METHODS

A RCT was conducted investigating pimecrolimus 1% cream vs triamcinolone 0.1% cream on UV-irradiated epidermal LC on 20 healthy volunteers. Punch biopsies were stained with antibodies to CD1a, HLADR and CD83.

RESULTS

Triamcinolone caused more depletion in UV-irradiated CD1a(+) epidermis relative to pimecrolimus treatment. (P=0.030). Using HLA-DR as a pan-marker for APCs, pimecrolimus caused marginally less depletion than triamcinolone (P=0.013). Using anti-CD83 as a maturation marker, UV-irradiated skin treated with pimecrolimus showed more mature LC than skin treated with triamcinolone (P=0.00090).

CONCLUSION

UV-induced changes in LC are minimally affected by pimecrolimus, compared with triamcinolone.

Cauterization of central cornea induces recruitment of major histocompatibility complex class II+ Langerhans cells from limbal basal epithelium

PURPOSE

The purpose of this study was to investigate the distribution and characterization of Langerhans cells (LCs) in the rat corneal epithelium and to compare the findings with those obtained earlier in the mouse corneal epithelium.

METHODS

Normal and cauterized corneal tissues were excised from Wistar rats, and immunofluorescence staining for major histocompatibility complex (MHC) class II, CD3, CD11c, CD11b, CD45, CD80(B-1), and CD86(B-2) was performed by confocal microscopy. The density of intraepithelial MHC class II+ LCs was quantified.

RESULTS

In the normal corneal epithelium, CD11c+ cells were exclusively distributed in the limbal and peripheral areas. Double staining showed that these cells were CD45 and MHC class II positive and B7 (CD80 or CD86) costimulatory molecules, CD11b, and CD3 negative, exhibiting a dendritic cell phenotype. In cauterized cornea, the expression of MHC class II was significantly enhanced in the limbal basal epithelium. The expression of the activation markers, CD80 and CD86, by MHC class II+ LCs was first present in the limbal basal epithelium as early as 4 hours after corneal inflammation and later throughout the entire corneal epithelium.

CONCLUSIONS

The present study demonstrates for the first time the distribution and characterization of LCs in the rat corneal epithelium, which largely resembles most of those observed in the mouse cornea. In the cauterized cornea, B7+ LCs were first present in the limbal basal epithelium, suggesting that these cells play an important role in corneal inflammatory reaction.

A note on langerhans cells in the oesophagus epithelium of domesticated mammals

Using the zinc-iodide osmium tetroxide (ZIO) method, TEM and immunohistochemistry (for CD1a and langerin), the study demonstrates Langerhans cells in the oesophageal epithelium of domesticated mammals (herbivores: horse, cattle, goat; omnivores: pig, dog, laboratory rat; carnivores: cat), although with variations between the species. The ZIO method and TEM showed this cell type in the cat and, sporadically, in the horse; CD1a (+) Langerhans cells were demonstrated in the ovine, porcine and murine oesophagus. Positive staining for langerin was detected in single cells of the caprine, canine, murine and feline oesophagus and more distinct in almost all the cell layers of the equine and porcine oesophagus epithelium. The findings are discussed comparing specifically the results for CD1a and langerin, whereby the latter C-type lectin may be of importance in species with a rather thick oesophagus epithelium, such as that present in the plantivorous and most of the omnivorous animals, where antigenic pressure is reduced.

Immunopathological mechanisms of eosinophilic oesophagitis

BACKGROUND

Eosinophilic oesophagitis (EO) is a chronic inflammatory disease of the oesophagus, with an emergent character, defined by the presence of a dense infiltrate by eosinophilic leukocytes restricted to the mucosa of this organ after excluding gastro-oesophageal acid reflux. It is manifested by chronic and/or recurrent dysphagia and episodes of oesophageal alimentary impaction, with great variation in terms of intensity, frequency, and duration of the attacks.

METHODS

An Internet-based search was performed for the most recent articles with relevant information concerning immunopathological mechanisms involved in EO.

RESULTS

Bibliographical data allow us to define that EO is related to an allergic or hypersensitivity-induced reaction after exposure to foods or inhalants, with increased prevalence of sensitisation to these allergens. Data published up to now suggest a cellular hypersensitivity reaction rather than a humoral one in the physiopathology of EO. In this disease, sensitised T-lymphocytes mediate a Th2 type response, releasing cytokines such as IL-5, with a possible Th1 component that requires further investigation. The function of the abundant CD8+ T-lymphocytes present in the oesophageal epithelium has yet to be explained. Mast cells also participate in epithelial inflammatory infiltrate in EO, and it is still unknown if its activation, mainly through IgE, contributes to the immunopathology of the disease even though EO rarely manifests immediate hypersensitivity reactions. IL-5 and different forms of eotaxins perform an important active role in the recruitment of eosinophils to the oesophagus.

CONCLUSIONS

EO is an immunologically complex and little studied entity that is associated with other allergic diseases and in which different effector cells participate, determining an immunological response of cellular rather than a humoral hypersensitivity reaction. The data available point out that EO is a disorder of the Th2 retarded immune response, in which the triggering factor might not be IgE. Although the final inflammatory phenomena observed in EO are common for the different patients, the cascade of inflammatory mediators that lead to them might not be identical in all cases, and the morphological and functional disorders observed in EO would represent the final convergence of different activation forms of the mechanisms of inflammation.

Langerhans cell histiocytosis

The clinical manifestations of Langerhans cell histiocytosis have been recognized for more than a century. For most of that time, physicians have viewed the disease from different perspectives, interpreting portions of its clinical spectrum as if they were distinct and unrelated entities. More recently, Langerhans cell histiocytosis has been unified into a single concept, though the disease continues to defy traditional classification. By most accounts, Langerhans cell histiocytosis appears to be a morphologically benign proliferation of inflammatory cells that escapes regulatory control mechanisms. Studies from patients with all stages of the disease, however, document clonal proliferation of immune processing cells (i.e., Langerhans cells), suggesting a malignant disease process. The most common ophthalmic manifestation of Langerhans cell histiocytosis is a solitary lesion of orbital bone, which typically responds to minimally invasive therapy. The best management of solitary orbital Langerhans cell histiocytosis is debatable and has been complicated by its recent designation as a risk factor for central nervous system disease. This article summarizes recent developments in understanding the biology of Langerhans cell histiocytosis, reviews its ophthalmic manifestations, prognosis, and the controversy surrounding treatment of isolated orbital disease.

Esofagitis eosinofílica

Eosinophilic esophagitis is characterised for a dense infiltration of the esophagus by eosinophilic leukocytes. The disease's origin is a local reaction to different antigens of which the patient presents previous sensitization, acquired by digestive, inhaled or even epicutaneous exposure. The esophagus contains different cellular types resident in its structure, with capability to participate in the capture, processing and antigens' presentation to T lymphocytes, which could initiate a T helper 2-type immunological response mostly mediated by interleukin-5, with a possible T helper 1-type component. Local production of immunoglobulin E could also participate in the pathophysiology of eosinophilic esophagitis, and for this reason, this disease can be considered a mixed-humoural and cell-mediated immunological disturbance. Studies directed to identificate responsible allergens must consider test for determine immunoglobulin E-mediated reactions as well as cell-mediated hyper-responsiveness responses. Main symptom of eosinophilic esophagitis are dysphagia and esophageal food impactations, which are conditioned by endoscopic alterations and motor disturbances objectively demonstrated by manometric recorders. Eosinophil and mast cell's activation and degranulation against responsible antigens cause damage over esophageal epithelium and dynamic disturbances over neuromuscular components in esophageal wall. Therapies proposed for eosinophilic esophagitis include control of antigen exposition, endoscopic dilation of stenosis and drugs with antieosinophilic effect; in this group topical steroids can be outlined for the capacity of them to restore the histology and the esophageal motility in parallel to vanishment of inflammation.

Pathogenic mechanisms of P. aeruginosa keratitis: a review of the role of T cells, Langerhans cells, PMN, and cytokines

The aim of this article is to review our current understanding of the role of cytokines, chemokines, T cells, Langerhans cells, and neutrophils (PMN) and their interactions in vivo in the host response to Pseudomonas aeruginosa ocular challenge. The cellular/cytokine network in vivo has begun to be unraveled, and the data discussed provide substantive evidence for a regulatory role of CD4(+) T cells (Th1 type) contributing directly to persistence of PMN in the cornea of susceptible C57BL/6 (cornea perforates) versus resistant BALB/c (cornea heals) mice. Additionally, in the susceptible mouse model, CD4(+) T cells interact with Langerhans cells and B7/CD28 ligation appears critical for antigen presentation and the susceptibility response. Various cytokines and chemokines (e.g., MIP-1alpha, IL-1beta, MIP-2, IL-12, and IFN-gamma) and their pattern of sustained upregulation after infection in susceptible versus resistant mice also will be discussed in light of an in vivo cytokine network. T-cell-mediated pathogenic mechanisms are of importance in development of the susceptible response to P. aeruginosa ocular infection. In the absence of T-cell infiltration into the cornea, PMN do not persist in the stroma, and cytokines and chemokines are better balanced, resulting in decreased stromal destruction and the resistance response.

ATPase and MHC class II molecules co-expression in Rana pipiens dendritic cells

Mammalian Langerhans cells are antigen-presenting cells located in different epithelia. These cells have a characteristic ultrastructural pattern, present a plasmatic membrane ATPase activity and constitutively express class II molecules of the major histocompatibility complex. ATPase-positive dendritic cells that are morphologically similar to Langerhans cells have also been found in amphibian epidermis. In order to demonstrate that ATPase-positive dendritic cells of amphibian epidermis express class II molecules and are present in other stratified epithelia, histochemical and immunohistochemical as well as ultrastructural analysis were performed. ATPase-positive dendritic cells and class II-positive dendritic cells were observed in epidermis, nictitant membrane and cornea. In epidermis the number of ATPase-positive dendritic cells was 656+/-186/mm2 while class II-positive dendritic cells was 119+/-45/mm2. Some ATPase-positive dendritic cells showed co-expression of class II molecules. These results suggest the existence of dendritic cell subsets in amphibians as is clearly demonstrated in mammals.

Failed antigen presentation after UVB radiation correlates with modifications of Langerhans cell cytoskeleton

Acute low-dose ultraviolet B radiation (UVR) impairs contact hypersensitivity (CH) induction in genetically defined strains of mice by a mechanism triggered by cis-urocanic acid (UCA) and dependent upon tumor necrosis factor-alpha (TNF-alpha). UVR, TNF-alpha, and cis-UCA cause similar morphologic changes among Langerhans cells, which spawns the speculation that UVR impairs CH induction in part by altering the Langerhans cell cytoskeleton. To examine this speculation, we studied the expression of vimentin in Langerhans cells after treatment with UVR, TNF-alpha, and cis-UCA. All treatments caused a reduction in expression of vimentin within the cytoplasm of Langerhans cells. Because partial loss of detectable vimentin may correlate with cytoskeletal disruption, we evaluated the effects of vinblastine, an agent that disrupts the cytoskeleton by disassembling microtubules, on Langerhans cell density and morphology. Epicutaneous treatment with vinblastine caused a reduction in Langerhans cell density, a loss of dendrites, and a reduction in vimentin expression. When dinitrofluorobenzene was painted on vinblastine-treated skin of BALB/c or C3H/HeN mice, only feeble CH was induced. Consequently, we propose that UVR prevents CH induction in susceptible mice by disrupting the cytoskeleton of Langerhans cells, thereby preventing them from carrying out their crucial role as antigen-presenting cells.

The role of dendritic cells in cutaneous immunity

This article reviews the role of dendritic cells in cutaneous immunity. Langerhans cells (LC) found in the epidermis are the best-characterized dendritic cell population. They have the ability to process antigen in the periphery, transport it to the draining lymph nodes (DLN) where they are able to cluster with, and activate, antigen-specific naive T cells. During migration LC undergo phenotypic and functional changes which enable them to perform this function. There are other less well-characterized dendritic cells including dendritic epidermal T cells, dermal dendrocytes and dermal "LC-like' cells. Although there is no evidence that dendritic epidermal T cells (DETC) can present antigen or migrate to lymph nodes, they do influence the intensity of cutaneous immune responses to chemical haptens. Antigen-presenting cells (APC) in the dermis may provide alternative routes of antigen presentation which could be important in the regulation of skin immune responses. Therefore, dendritic cells are vital for the induction of immune responses to antigens encountered via the skin. LC are particularly important in primary immune responses due to their ability to activate naive T cells. The faster kinetics of secondary responses, and the ability of nonprofessional APC to induce effector function in previously activated cells, suggest that antigen presentation in the DLN may be less important in responses to previously encountered antigens. In these secondary responses, dendritic and nondendritic APC in the skin may directly induce effector functions from antigen-specific recirculating cells.

Dendritic cell/lymphocyte clustering: morphologic analysis by transmission electron microscopy and distribution of gold-labeled MHC class II antigens by high-resolution scanning electron microscopy

Dendritic cells (DCs) are potent antigen-presenting cells for a variety of immune responses; however, their mechanism of action has not been established. It is known that DCs can cluster with one another and with other cell types during in vitro immune responses, and clustering may be essential for the activation of resting lymphocytes. In this study, ultrastructural examination of clusters that form during extended culture of enriched rat splenic DCs (approximately 70% DCs) is reported. DCs were readily distinguished from other cell types, which included lymphocytes and macrophages. DCs displayed characteristic veils and/or dendritic processes that intertwined with processes of other cells within the cluster, or extended from the cluster periphery. Occasional DCs contained large vacuoles lined with small vesicles. A paramount feature of DCs is their constitutive expression of high levels of surface major histocompatibility complex class II antigens. The surface distribution of class II antigens on clustering DCs was examined using 10 nm immunogold labeling techniques and high-resolution scanning electron microscopy. DCs were readily distinguished by morphologic criteria, and examination of various surface membrane regions revealed a differential distribution of class II antigens. Gold label was frequently distributed in linear arrays and clusters, suggesting a cytoskeletal role in the recycling/redistribution of Class II antigens. These morphologic findings further an understanding of basic DC biology and their mechanism of action as antigen-presenting cells.

Three-dimensional reconstruction and stereometric analysis of Langerhans cells in mouse epidermis

In the presented studies stereometric analysis and spatial reconstruction was performed on two Langerhans cell (LC) types. One was free of LC-I and the other contained LC-II Birbeck granules in the perinuclear space. The presented stereometric analysis demonstrated significant differences between the so-distinguished two cell types. Differences were observed not only in the number and distribution of Birbeck's granules but also in the areas of smooth and rough endoplasmic reticulum, in the area of vesicles surrounding Golgi apparatus, in the volume of cisterns of the apparatus, and in the ratio of cell nucleus area to its volume. Differences noted between the two cell types were of quantitative character. They might result from different stages of differentiation of the cells from their precursors in the epidermis or from distinct functional stages of the cells.

Internalization of Ia molecules into Birbeck granule-like structures in murine dendritic cells

Dendritic cells isolated from the draining lymph nodes of mice sensitized epicutaneously with hapten are potent antigen-presenting cells and contain Birbeck granules and cored tubules characteristic of antigen-activated epidermal Langerhans cells. We used immunogold labeling and transmission electron microscopy to follow the internalization of Ia molecules in these antigen-presenting cells. We found that Ia molecules were internalized into Birbeck granule-like structures in the antigen-activated dendritic cells. Computer reconstruction of serial sections of the dendritic cells demonstrated that these structures span the cytoplasm from the cell membrane to the nuclear membrane and are associated with lysosomes. The internalization of Ia molecules into these structures supports the hypothesis that the Birbeck granule-like structures are derived from the cell membrane and are involved in the antigen-processing/presenting function of the dendritic cells.

Preparation of B lymphocyte-specific alloantisera by skin implant immunization of cattle

B lymphocyte-specific antisera were prepared by immunizing cattle on either one or two occasions with a subcutaneous implant of allogeneic skin and subsequently absorbing the antisera with platelets. After absorption 15/26 antisera displayed B lymphocyte-specific activity. Titres against B-enriched cells were 8-64 while residual titres against B-depleted cells were 1-8. In comparison, 3-6 immunizations with allogeneic leucocytes produced antisera of similar peak cytotoxic titres against donor PBL, and after platelet absorption 8/15 antisera displayed B lymphocyte-specific activity. Titres against B-enriched cells were 8-64 while residual titres against B-depleted cells were 2-8. The skin implant method was less time-consuming than the leucocyte immunization method.

The relationship of corneal Langerhans cells to herpes simplex antigens during dendritic keratitis

The corneal migration and topographic distribution of Langerhans cells (LC) in relation to herpes simplex virus antigens was studied during the course of dendritic keratitis in inbred mice. Corneal epithelial sheets from infected mice at selected time points were "double stained" for Ia-positive Langerhans cells and HSV antigens, using a sequential avidin biotin immunoperoxidase and glucose oxidase technique. The amount of HSV antigen was maximum at day 2 paralleling the clinical time course, with most corneal epithelium HSV antigen negative by day 8. LC were seen in peripheral corneas by day 2 and in paracentral and central cornea by day 8, with peak numbers detected between days 8 and 11 post-infection. Although HSV antigens and LC were simultaneously detected within corneal epithelium, LC were not observed in anatomic juxtaposition to HSV antigens, even after reinoculation of infected corneas with HSV on day 14 following the primary infection. These data suggest that local factors in the corneal epithelium other than HSV antigens per se may be chemotactic for LC during the course of dendritic keratitis.

Replacement of Langerhans cells in murine palate

Palates from C3H mice were implanted onto prepared graft beds in histocompatible F1 hybrid mice. Biopsies taken 1, 2, 4, 8, and 16 wk later were prepared to demonstrate Langerhans cells (LC) of C3H and F1 (host) origin. After 1 wk only occasional LC (all of C3H origin) were present. By 2 wk total LC numbers had increased to a level approximately 50% greater than in control (non-implanted) palate, with most of this increase due to C3H LC proliferation. From 4 through 16 wk total LC numbers were not significantly different from those of control palate. During weeks 2 through 16 the percentages of LC of F1 origin were 31, 70, 39, and 19% respectively. These results indicate an increased proliferation of C3H LC with an initial migration of F1 LC which stops as C3H LC numbers increase.

Large corneal grafts can be successful

Seventeen grafts of 10 mm in diameter or larger have been performed on 16 eyes of 15 patients. The major indications for surgery were infections or perforations or both. Follow-up has ranged from 8-54 months (mean 26.4). The 4 year survival probability was 0.64. Although the procedure was successful in saving all but one eye and restored useful vision in the majority, complications including cataract, glaucoma, graft rejection episodes and infections were encountered. The management of these complications is described. At final review, 13 eyes had clear grafts including those in whom regraft had been performed. These results have only been achieved by close co-operation between patients and the medical team responsible for their care.

Immunoregulation of dermatophytosis

Dermatophytoses are superficial infections caused by a group of fungi, the dermatophytes, which invade keratinized tissue of skin, hair, and nails in humans and animals. The importance of normal immune function in resistance to dermatophytoses is substantiated by an increased susceptibility to chronic infection seen in patients with impaired immunological responses. Humoral and cell-mediated immunities are both elicited during the infection. However, specific antibodies to dermatophytes do not seem to play a major role in protective immunity. On the other hand, the development of cell-mediated immunity during the infection is critical in eliciting resistance to the disease. For instance, resolution of the disease in both naturally and experimentally infected humans and animals correlates with the development of delayed-type hypersensitivity (DTH), whereas persistence of infection is frequently accompanied by poor in vitro blastogenic response and absent DTH. Furthermore, in experimentally infected mice, immunity to dermatophyte infection can be achieved by adoptive transfer of lymphoid cells, but not by serum, of infected donors. The present review includes an overview of published work and current research on the cellular events implicated in immunity to dermatophytosis. The role of humoral factors in such immunoregulation is also discussed.

Langerhans cell histiocytosis: an unusual case illustrating the value of immunohistochemistry in diagnosis

The morphological features of Langerhans cell histiocytosis (histiocytosis X) are characteristic but the diagnosis can on occasion be difficult. A case is presented that illustrates the diagnostic value of immunohistochemistry in the differential diagnosis of this condition. The cells of Langerhans cell histiocytosis were found to express CD1, CD4, CD11b and CD11c. They also reacted with EBM11, UCHM1, KB61 and HLA-DR. Occasional cells showed nuclear staining with Ki67, but no other lymphoid antigens were detected. Immunoreactivity of the cells of Langerhans cell histiocytosis with antibodies that recognize antigens present on macrophages provides further evidence for immunological similarities between these cell types.

Quantitative studies on Langerhans cells in mouse corneal epithelium following infection with herpes simplex virus

Dendritic Langerhans cells (LCs) were identified in flat-mount preparations of mouse corneal epithelium after staining for ATPase activity. They were found predominantly in the limbus, but after inoculating the cornea with HSV1 strain SC16 LC, numbers increased both in the limbus and the central cornea. Numbers of LCs reached a maximum on day 8 and if severe keratitis was present remained high at least until day 22. A small but significant increase in LCs was also found in the opposite, uninoculated eye in mice with severe damage in the inoculated eye. After HSV inoculation on the snout, 60% of mice had corneal disease in the eye on the inoculated side; in such mice corneal LCs were at a maximum 18 days after inoculation. The increase in LC numbers was similar whether inoculation was into the cornea or in the snout. After corneal inoculation the cells were distributed fairly evenly over the corneal surface, with accumulations limited to epithelial ulcers. However, after inoculation on the snout, numerous clusters were seen over the epithelial surface, often surround by epithelium devoid of LCs.

The presence of bacteria in the oral epithelium in periodontal disease. III. Correlation with Langerhans cells

Langerhans cells (LC) are cell types found in the skin and gingiva. LC have immunological functions as phagocytic cells and as antigen-presenting cells for T and B lymphocytes. Sections from biopsies of the gingiva in cases of periodontal disease were found to have increased numbers of LC. These biopsies also contained intragingival bacteria. Serial sections of frozen specimens of human gingiva were prepared for staining. Hematoxylin and eosin were used for tissue survey, the Gram stain for assessment of bacterial invasion, anti-Leu-6 monoclonal antibody associated with peroxidase technique (PAP) to identify LC, antibacterial sera to Bacteroides gingivalis and Actinobacillus actinomycetemcomitans associated with peroxidase to specifically identify these two common periodontopathogenic bacteria. Additional positive identification of bacteria was performed by preparing the same histological section containing gram-stained particles for scanning electron microscope and transmission electron microscope LC confirmation. The results suggest that the increased number of LC seen in diseased sites of oral epithelium containing intragingival microorganisms may be one of the host immune mechanisms to penetration by bacteria.

Activation marker analysis of mononuclear cell infiltrates of oral lichen planus in situ

Monoclonal activation markers (Ia, Tac, T9, and 4F2) were used to detect the degree of activation of mononuclear cells in the inflammatory infiltrates of oral lichen planus in situ. In addition the specimens were stained with the following monoclonal antibodies: T4, T8, T11, M1, and pan-B. T-lymphocyte was the predominant cell type in the inflammatory infiltrates. According to the results of the activation marker analysis, the majority of the T-lymphocytes were resting. However, activated cytotoxic T8 and 4F2 T-cells were located close to damaged basal cells; this finding may suggest that they are responsible for the damage and supports the claim that a cell-mediated immune response participates actively in local pathogenetic mechanisms in oral lichen planus.

Effect of orally administered aromatic retinoid on murine Langerhans cells

The effect of orally administered aromatic retinoid (Ro 10-9359) on murine epidermal Langerhans cells (LC) was studied in vivo and in vitro. Daily administration of retinoid caused a transient increase in LC density, as determined by staining for Ia antigens, during the first few days of treatment and thereafter a continuing decrease that reached a maximum at 2 weeks. In addition, the morphology and location in the epidermis had been altered. When the treatment was continued to 4 weeks, the density of LC returned to normal. The Ia-antigen-presenting function of epidermal cells to an allo-Ia-reactive cloned T cell line was elevated at all stages of retinoid treatment examined. This elevation did not correlate with the density of histochemically stainable Ia+ LC. These findings suggest that orally administered retinoid profoundly alters the functional capacity of Ia+ LC.

Extent and diversity of inflammatory cell infiltrates in squamous cell carcinomas and basal cell epitheliomas of the head and neck

Using monoclonal antibodies reactive with Langerhans' cells (LCs), macrophages, and T cell subpopulations, the density and proportions of cells of the immune system of the normal oral mucosa were determined immunohistochemically, and compared with findings in oral squamous cell carcinomas (SCC) and basal cell epitheliomas (BCE). In normal oral epithelia, the dominant cell type was the LC, positive for CD 1, and expressing HLA-DR antigens (DR+). Many intraepithelial cells were lymphocytes of the suppressor/cytotoxic phenotype (CD 8+), which was also the most prominent cell type in the normal mucosal stroma. Significant differences were observed for the content of CD 8-, OKM 1-, and CD 4-positive cells in the epithelium of normal oral mucosa, SCC, and BCE, and for the amount of CD 1-positive Langerhans cells in the connective tissue of the different groups of tissues. When CD 4/CD 8 ratios were calculated, differences between SCC and BCE became most evident. A CD 4/CD 8 ratio greater 0.5 was seen to be characteristic for BCE. Thus, in contrast to the striking preponderance of suppressor/cytotoxic lymphocytes (CD 8+) in SCC, BCE showed typically almost balanced numbers of suppressor/cytotoxic (CD 8+) and helper/inducer (CD 4+) lymphocytes. This finding further underlines the biological differences recognized between these most common neoplasias of the head and neck.

Age-associated changes in Langerhans cells of murine oral epithelium and epidermis

Oral mucosa and skin of older individuals are immunologically less responsive to a range of allergens, but it is not known whether this is due to changes in the number of Langerhans cells or to impaired cell function. EDTA-separated epithelial sheets from the cheek and palate mucosa, and from ear aN< footpad skin of three-month-old and 24-month-old C57BL/6NNia mice were stained for ATPase, beta-glucuronidase activity and Iab-surface antigen to demonstrate Langerhans cells. The general distribution of such cells was unchanged with age, but those in epithelia from the old mice were more varied in shape, with irregular celL bodies and more elongated dendritic processes. The numerical density of Langerhans cells in old mice was reduced by 30-59 per cent compared with that in young mice.

An immunohistochemical study of oral lichen planus

Specimens from 22 cases of oral lichen planus were prepared for studies of the basement membrane zone by immunohistochemical and histochemical methods. Langerhans' cells, monocytes, and lymphocytes constitute the predominant cells of the inflammatory infiltrate, thus indicating a cell-mediated response. Lymphocyte-related necrosis of epithelium and nonspecific vasculitis are associated with an altered basement membrane zone. Immunoproteins, including IgG, IgA, IgM, and C'3 as well as fibrinogen, are present and distributed in a nonspecific pattern.

Spatial distribution of Langerhans' cells and T-lymphocyte subpopulations in human tympanic membrane and aural cholesteatoma

Immunohistochemical analysis of human cholesteatoma matrices revealed the presence of Langerhans' cells and T-lymphocytes. Through cell-to-cell interaction, Langerhans' cells probably play a key role in skin-related disorders, including cholesteatomas. They probably originate from a mobile cell population of monocyte origin and migrate into and out of the body's lining. Their custodial function is often carried out in close relation with T-lymphocytes. Monoclonal antibodies against Langerhans' cells and T-lymphocyte membrane receptors reveal the presence of these cell populations in cholesteatoma matrices but not in the tympanic membrane. Langerhans' cells and T-cell "traffic" through cholesteatomas are discussed in relation to the pathogenesis, natural course and recurrence of cholesteatomas. Through immunopathologic evaluation the clinical aggressiveness of a cholesteatoma may become predictable. It may even have consequences for the future handling of cholesteatomas.

Long-term effects of local ionizing radiation treatment on Langerhans cells in mouse footpad epidermis

Langerhans cells (LC) were studied with ADPase histochemistry in sheets of hind footpad epidermis from groups of CBA/H mice. Single, local 20-Gy doses of 250-kV x-rays were administered to the right hind feet of the mice when they were 3-4 months old, and LC were counted at intervals ranging from 2 to 24 months later. In unirradiated mice, aged 5-19 months, the mean density of LC in footpad was 1521-1617 cells/mm2. It dropped to 1137 +/- 86 cells/mm2 (mean +/- SE) in untreated 28-month-old mice. At times from 2-15 months after irradiation, normal mean densities of LC were present in footpad epidermis. On average, LC numbers were subsequently reduced to 1078 +/- 65/mm2 by 19 months after irradiation (71% of the cells in age-matched controls) and to 789 +/- 53/mm2 by 24 months (59% of the cells in age-matched controls). Loss of cells was focal. Chronic radiation-induced fibrosis and damage to circulatory function in skin may have contributed to impaired replacement of LC from bone marrow precursors. The possibility that late radiation-related depletion of the LC population permits development of skin tumors as a delayed consequence of exposure to ionizing radiation is discussed.

A comparison of conjunctival and nonocular dendritic cells utilizing new monoclonal antibodies

Langerhans cells belong to the dendritic cell family. Their presence in the conjunctiva and cornea has been demonstrated by means of various membrane and cytoplasmic markers. Utilizing OKT6, a monoclonal antibody that specifically binds to Langerhans cells in conjunction with la histocompatibility antigens (HLA-DR), and a new panel of monoclonal antibodies, we compared the population density and characteristic phenotypes of Langerhans cells in normal conjunctiva with those in normal epidermis. A greater density of Langerhans cells was noted in epidermis in comparison with conjunctiva. Various areas of the conjunctiva and cornea were mapped for Langerhans cell distribution. The T6/la ratio of Langerhans cells in conjunctiva was notably different from that in skin. Utilizing the Prolm2 marker, we identified non-Langerhans dendritic cells in the substantia propria and in the basilar epithelium of the conjunctiva, antigen-processing cells probably identical to the interdigitating dendritic cells of lymph nodes.

Major histocompatibility complex class II antigen (HLA-DR, DQ and DP) expression in human fetal skin

Monoclonal antibodies were used to analyse skin samples from human fetuses (15-19 weeks gestational age) for the presence of class II major histocompatibility antigens (HLA-DR, DQ and DP). Cells expressing these antigens were clearly demonstrated within the epidermis from a proportion (4/7) of cases and were completely absent from the others. The negative samples were uniformly those with an epidermis of three cell layers or less. Such material may prove useful in studying the induction of class II antigen expression and the role of these antigens in allostimulation.

Preferential induction of antigen-specific contrasuppressor T lymphocytes by trinitrophenyl (TNP)-substituted Langerhans cells

We have tested the ability of trinitrophenyl (TNP)-labelled antigen-presenting cells (Langerhans cells (LC) and peritoneal macrophages (M phi)) administered intravenously to induce cells that mediate and regulate contact sensitivity. TNP-M phi fail to induce contrasuppressor cells (Tcs) but activate efferent T suppressor (Ts) cells. However, the activity of immune cells can be recovered after removal of Ly 2 Ts cells. In sharp contrast, TNP-substituted purified LC produced a significant contact sensitivity reaction, which is roughly equivalent to that achieved by skin sensitization with picryl chloride. Immune cells from these animals were relatively resistant to suppression by antigen-specific Ts cells, and we have found that their resistance is due to the presence of Ly 1, Vicia villosa lectin adherent, I-J+ cells. The Tcs cell induced by TNP-LC is indistinguishable by surface markers and function from Tcs cell found in mice injected with antigen-antibody complexes. Both these Tcs cells are capable of protecting immune cells from the effects of suppression by antigen-specific Ts cells if added in the proper sequence. Although they have identical surface phenotypes, it is not known at present whether or not Tcs cells induced by two different antigen presentations are identical. The possible reasons why LC are such potent inducers of contrasuppression are discussed.

Loss of allogeneic T-cell activating ability and Langerhans cell markers in human epidermal cell cultures

Human Langerhans cells are the only epidermal cells that express the T6 and HLA-DR antigens and are responsible for the in vitro allogeneic T-cell proliferative responses in the mixed skin cell lymphocyte reaction (MSLR). To investigate the presence of Langerhans cells in normal human epidermal cell cultures, epidermal cell suspensions obtained from normal human skin specimens and from the subsequent epidermal cell cultures were analyzed by indirect immunofluorescence for the presence of T6 and HLA-DR determinants. In parallel, MSLRs were conducted with suspensions of cultured epidermal cells as stimulatory cells. These studies present evidence that when human epidermal cells are grown in culture, they loose both the ability to stimulate the proliferation of allogeneic T lymphocytes in vitro and their expression of HLA-DR and T6 antigens. The T6 antigens were lost during the first 2 weeks of culture, while HLA-DR determinants were still expressed by a small number of cells and were progressively lost through duration of cultures. The loss of HLA-DR antigens closely paralleled the progressive inability of human epidermal cells in culture to stimulate allogenic T cells in MSLR.

A subset of human cord blood mononuclear cells is similar to Langerhans cells of the skin: a study with peanut agglutinin and monoclonal antibodies

Mononuclear cells were fractionated from human cord blood by affinity chromatography on immobilized peanut agglutinin, as previously described (Rosenberg et al., Hum Immunol 7:67, 1983). The PNA+ subset was found to be composed mainly of a population of cells phenotyped as Ia+, T6+, M01+, and MY4+. The presence of mononuclear cells coexpressing these antigens was demonstrated by three techniques: double labeling immunofluorescence using FITC and rhodamine conjugated goat antimouse IgG; fluorescence activated cell sorter (FACS); and by direct counting (under the microscope) of cells stained by either individual or a combination of a variety of monoclonal antibodies. The PNA+ cells expressed cytoplasmic structures similar to Birbeck granules. In view of the fact that Langerhans cells of the skin share a similar phenotype and express Birbeck granules, we suggest that this subset may be the precursor of the Langerhans cells of the skin. In addition, these cells may also be the precursors of the dendritic cells found in the spleen, lymph nodes, thymus, and liver.

Peanut agglutinin. A useful marker for histiocytosis X and interdigitating reticulum cells

We studied the peanut agglutinin (PNA) staining patterns of histiocytosis X (H-X) (three cases, including one case of Letterer-Siwe disease) and well-characterized cases of malignant histiocytosis (two cases) and monoblastic leukemia (one case) in paraffin-embedded specimens. H-X cells showed staining identical to that of interdigitating reticulum cells, with unique paranuclear and cell surface deposits of reaction products. Thus, H-X cells were easily distinguished from benign macrophage-histiocytes, which show diffuse cytoplasmic staining, and malignant cells of malignant histiocytosis and monoblastic leukemia, which did not stain with PNA, PNA staining proved more useful than Leu-M1 antibody for this purpose, since neither interdigitating reticulum cells in ten reactive lymph nodes nor Langerhans'-type cells in three cases of H-X were stained with Leu-M1 antibody. These observations support a close relationship between H-X cells and interdigitating reticulum cells, and demonstrate the usefulness of PNA for the identification of these cells in paraffin-embedded material.

Derivation of Langerhans cell granules from cytomembrane

OKT6 monoclonal antibody has been shown to react selectively with Langerhans cell (LC) cytomembrane in human skin. Taking advantage of this property, we examined the stainability of LC granules with OKT6 using immunoperoxidase method at the ultrastructural level. It was found that the delimiting membranes of LC granules, both attached to the cytomembrane and in the cytoplasm, were specifically stained in the epidermal sheet. These findings suggest that LC granules are derived from invagination of LC cytomembrane and retain T6 antigen. We employed two new methods: one is promotion of endocytosis by incubating the epidermal sheet in tissue culture medium with OKT6 at 4 degrees C and further incubation without OKT6 at 37 degrees C, and the other is the use of saponin to facilitate penetration of the secondary antibody through the cytomembrane of LC. In the LC cytoplasm only the delimiting membrane of the granule was stained; other membranous organelles, such as mitochondria and rough endoplasmic reticulum, did not react.

Langerhans cell surface densities in rat oral mucosa and human buccal mucosa

We determined surface densities of Langerhans cells (LCs) in rat oral mucosa and human buccal mucosa by enumerating ATPase-positive dendritic cells in epithelial whole mounts. For the rat, mean surface densities per mm2 were 160 in anterior buccal mucosa, 640 in posterior buccal mucosa, 430 in the palate and 340 in the tongue. Human buccal mucosa showed a density of 890 cells per mm2. We conclude that LC densities in oral mucosa approximate those of external body sites, making them available in numbers sufficient to accomplish their postulated antigen-presenting functions.

Heterogeneity of dermal OKT6+ cells in inflammatory and neoplastic skin diseases

This immunopathologic study of both normal and pathologic skin specimens (contact dermatitis [CD], lichen planus [LP], cutaneous T cells lymphoma [CTCL], and histiocytosis X [HX]) allowed as to differentiate four types of dermal OKT6+ cells: (1) cells with the same morphologic features as epidermal Langerhans cells (LCs), rarely found in either normal or pathologic dermis; (2) cells structurally similar to LCs but lacking Birbeck granules (BGs), found mainly in CD and LP; (3) larger cells rich in cytoplasmic organelles, only 5% of which contained BGs. They were especially common CTCL; and (4) cells typical of HX.

Identification of Langerhans cells in human gingival epithelium

The purpose of this study was to qualitatively compare three recent techniques of Langerhans cells detection in oral epithelium and to quantitatively compare Langerhans cells in clinically normal and clinically inflamed human gingival biopsies. Eleven subjects were selected who displayed chronic periodontitis and moderate gingival inflammation. A quadrant associated with clinically inflamed tissues was not treated, while the remaining teeth were scaled and root-planed. Two gingival biopsies were taken: clinically normal, treated tissue; and clinically inflamed, untreated tissue. Langerhans cells were stained using HLD-DR, S-100 and OKT6. They were quantitated using a standard grid for OKT6-stained sections only. Approximately 5 times as many Langerhans cells were identified in the biopsy specimens of clinically inflamed human gingiva as in clinically normal gingiva of the same patient. Of the methods studied, OKT6 was qualitatively determined to be the best for visualization of these cells. An immunologic role in the host response to chronic periodontal disease is postulated for Langerhans cells.

Quantitative analysis of immunocompetent cells in human normal oral and uterine cervical mucosa, oral papillomas and leukoplakias

Using monoclonal antibodies reacting with T-cell subpopulations, Langerhans cells and macrophages, the number and distribution of cells of the immune system in normal oral and cervical mucosa was determined and statistically compared with that in oral papillomas and oral leukoplakias. Increased numbers of labelled cells were found in oral leukoplakias and particularly in oral papillomas. In the epithelium of all specimens, Langerhans cells and T-lymphocytes of the suppressor/cytotoxic phenotype as well as of the helper phenotype were seen. Suppressor/cytotoxic and helper T-lymphocytes were in equal numbers in the epithelium of oral papillomas, but were about 2:1 in all other lesions. In normal oral epithelium, macrophages were rare but were in greater numbers in leukoplakias and papillomas. In the connective tissue of all lesions, more labelled cells were present than in epithelium with T-lymphocytes predominant. Although Langerhans cells were rare in connective tissue, many were seen in oral papillomas.

Ultrastructural identification of Ia positive dendritic cells in the lactating rat mammary gland

Dendritic cells which express Ia antigen have been demonstrated for the first time in the lactating rat mammary gland. Ultrastructurally, the dendritic cells appear as electron-lucent pale cells interspersed among the epithelial cells of the alveoli, forming a cell population distinct from classical macrophages. They show morphological resemblance to the dendritic cells of lymphoid organs as well as the Langerhans cells of skin. The Ia antigen has been localised by electron microscopic immunocytochemistry on the cell membrane and endocytotic vesicles and tubules. Ia positive cells are also seen in the stroma of the mammary gland. It is proposed that the dendritic cells of the mammary gland belong to the lineage of epidermal Langerhans cells and lymphoid dendritic cells, subserving an immunological role in the lactating breast.

Dynamic changes in epidermal Ia-positive cells in allergic contact sensitivity reactions in mice

In mice sensitized with trinitrochlorobenzene, serial changes in epidermal Ia-positive cells were studied at various times after challenge. Until 3 days post-challenge, the Ia-positive cells consisted only of dendritic Langerhans cells; their number was decreased but they were significantly enlarged, with extending dendrites. Some Langerhans cells were also found surrounding a hair follicle, extending their dendrites toward the follicle like the spokes of a wheel. From 3 to 9 days after challenge, keratinocytes also began to express Ia antigens in the epidermis in addition to Langerhans cells, whose size diminished. This suggests that there are two phases in the response of the epidermal Ia antigens in contact sensitivity reactions, i.e. an early phase in which enlarged Langerhans cells are the only Ia-positive cells in the epidermis, and a late phase in which keratinocytes take over as the major Ia-positive cells, while Langerhans cells resume their original size. Ia antigen expression on keratinocytes in this late phase probably plays a crucial role in completely eliminating allergens deposited on the keratinocytes.

Ultrastructural immunogold labelling of human Langerhans cells enriched epidermal cell suspension

Colloidal gold particles are well suited as markers in electron microscopy. Indirect immunogold staining was used to identify cell membrane antigens defined by monoclonal antibodies OKT6 and BL6 on human Langerhans cells (LC) in suspensions. Isolated epidermal cells were obtained by skin trypsinization and enriched or depleted in OKT6 positive on BL6 positive LC using the panning method: incubation of OKT6 or BL6 preincubated cells on immunoglobulin coated dishes. Indirect immunogold staining was then performed after prefixation in 2% paraformaldehyde. In LC enriched suspensions, only LC exhibited a specific membrane labelling with OKT6 or BL6 recognized by the presence of small evently distributed gold granules. Neither Birbeck granules, nor other cytoplasmic organelles, were labelled. No other epidermal cells were found positive. In LC depleted suspensions, no labelling was observed. Immunogold labelling on LC enriched suspensions after panning is now in progress for the qualitative evaluation and the quantitative analysis of cell surface constituents and antigens expressed by human dendritic epidermal cells.