Lymphocyte subsets and Langerhans cells/indeterminate cells in erythema multiforme

Pattern-Specific Loss of Desmoplakin I and II Immunoreactivity in Erythema Multiforme and its Variants: A Possible Aid in Histologic Diagnosis

Erythema multiforme (EM), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) comprise a family of mucocutaneous diseases associated with significant morbidity and mortality. Previous studies have confirmed the presence of autoantibodies to desmoplakin (Dp) I and II in patients with EM, SJS, and TEN. Truncated Dp production leads to characteristic changes visible on light microscopy: perinuclear clumping of keratin filaments and dyskeratotic keratinocyte. Based on these observations, the question arises as to whether a loss of Dp immunoreactivity in skin biopsies could serve as a diagnostic marker of EM, SJS, and TEN. This study analyzed Dp immunostaining patterns in 20 patients with EM or SJS/TEN. To assess the specificity of this approach, Dp immunostaining was also performed on specimens from patients with 5 potential histologic mimics of EM, SJS, and TEN. All of the samples from patients with EM, SJS, and TEN demonstrated absent or markedly diminished staining for Dp. A χ test demonstrated a statistically significant difference between the staining patterns in EM, SJS, and TEN and each of the other diagnostic groups that were investigated. This is the first report demonstrating statistically significant specificity of Dp staining patterns in EM/SJS/TEN as compared with other interface dermatitides.

Immunohistochemical Expression of Apoptotic Markers in Drug-Induced Erythema Multiforme, Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are considered to be severity variants of the same disease, which is almost always associated with drug intake. In contrast, erythema multiforme (EM) is a disorder regarded as only rarely caused by drugs. Keratinocyte apoptosis has been shown to play an important part in the pathogenesis of SJS and TEN, whilst its role in EM remains controversial. To determine the expression of apoptosis-associated molecules Fas, Fas ligand (FasL), Bcl-2 and Bax in the above disorders, an immunohistochemical analysis was performed. We studied both lesional skin from thirty patients having drug-induced EM and 5 cases classified within the SJS/TEN spectrum and normal skin samples. We found a keratinocyte overexpression of Fas antigen, an important molecule mediating apoptosis, not only in SJS and TEN but also in EM. Another noteworthy finding was the strong expression of Bcl-2, a protein known as blocking apoptosis, along the basal layer and in the dermal infiltrate both in SJS/TEN and in EM. Taken together, these findings suggest that Fas-dependent keratinocyte apoptosis may play a part in the pathogenesis of both SJS/TEN and EM. Fas-mediated cell death may be partially suppressed by the Bcl-2 protein.

Rituximab, a new treatment for difficult-to-treat chronic erythema multiforme major? Five cases

BACKGROUND

Erythema multiforme major (EMM) is an inflammatory disease affecting skin and mucosae, often triggered by infection with Herpes simplex virus. Some patients have a chronic disease associated with antidesmoplakin autoantibodies, but the pathophysiology remains to be elucidated. First-line treatment is antiviral therapy. With treatment failure or in patients without herpes-triggered disease, thalidomide is effective but has neurological side-effects. Alternatives (dapsone, immunosuppressant agents) are not codified. For many patients, systemic steroids use is chronic. The immunosuppressant drug rituximab (RTX) may be effective.

OBJECTIVES

We report five cases of severe chronic EMM treated with rituximab (RTX).

METHODS

Five patients with severe chronic EMM for 9-20 years received RTX after failure or side-effects of several treatments, especially antiviral therapy and thalidomide. All had chronic use of steroids. Four patients had antidesmoplakin autoantibodies.

RESULTS

Four patients experienced complete or quasi-complete remission of EMM with withdrawal of steroids and one patient partial remission, for 3-11 months. Disease relapsed in all patients, and three received a second cycle of RTX with shorter duration of efficacy. Two patients received a third cycle, one without efficacy.

CONCLUSION

The use of RTX for many autoimmune diseases, especially pemphigus, is increasing. Chronic EMM, especially EMM associated to antidesmoplakin autoantibodies, is an inflammatory disease in which the role of B cells is not well understood. However, we report a favourable benefit of RTX treatment for months in five patients with severe disease. RTX could be a therapeutic option in severe, difficult-to-treat EMM.

Expression of interleukin-17 in lesions of erythema multiforme may indicate a role for T helper 17 cells

Introduction

The aim of this study was to evaluate levels of interleukin (IL)-2, IL-6, IL-8, IL-10, IL-17A and interferon γ (IFN-γ) in the serum of patients with erythema multiforme (EM) and to search for the presence of IL-17-expressing cells in lesional samples of EM.

Material and methods

A total of 32 patients (22 females and 10 males) diagnosed with EM of the minor or major type were included in the study. Levels of IL-2, IL-6, IL-8, IL-10, IL-17A and IFN-γ in the serum were determined and compared with healthy controls. Biopsy specimens were stained with haematoxylin and eosin (HE) and monoclonal antibodies to CD4, CD8 and IL-17 for immunohistochemical examination.

Results

IL-2, 6, 8 and 17A were significantly higher in the patient group (p = 0.016, p = 0.001, p = 0.004, p = 0.006, respectively) and levels of IL-10 were significantly lower than in the control group (p = 0.046). The cellular infiltrate in lesions of EM was composed mainly of CD4+ T lymphocytes. The presence of IL-17-expressing cells, at proportion of 5 to 50%, was observed in the infiltrate.

Conclusions

The demonstration of IL-17-expressing cells in lesions of EM in this study has brought forth the assumption that Th17 cells may be involved in the pathogenesis of EM.

Erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis: a comparative review

BACKGROUND

Human erythema multiforme (EM) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) are separate conditions. There is no consensus on classification criteria for the eponymous diseases in animals.

RESULTS

Animal EM is very different from 90% of human EM, which is herpes virus associated (HAEM). Animals lack acrally distributed, typical raised targets. Unlike canine parvovirus 'EM', HAEM is not an active infection. Animal EM is often attributed to drugs, but this is rarely proved. Conversely, human and animal SJS/TEN are almost identical, life-threatening disorders of epidermal necrosis and detachment, typically triggered by drugs (occasionally by infectious agents). Both EM and SJS/TEN are mediated by cytotoxic lymphocyte responses against altered keratinocytes (infectious agents or drugs). Apoptosis results from direct cytotoxicity or through soluble mediators, namely Fas ligand, granzymes, perforin and granulysin. Diagnosis in humans is clinicopathological, with emphasis on clinical lesions; histopathology confirms the pathological process as interface (cytotoxic) dermatitis. Human EM is self-limiting; only recurrent and rare persistent cases require antiviral/immunosuppressive therapies. Drug-induced EM responds to drug withdrawal. Idiopathic canine EM (>40%) is usually chronic, refractory to treatment and may represent heterogeneous conditions. Early identification and removal of the causative drug and high-quality supportive care are critical in SJS/TEN. Mortality rate is nevertheless high.

CONCLUSIONS AND CLINICAL IMPORTANCE

(1) Histopathological lesions do not reliably differentiate EM, SJS and TEN. (2) A multicentre study to develop a consensus set of clinical criteria for EM and SJS/TEN in animals is overdue. (3) No adjunctive therapies, including intravenous immunoglobulin and ciclosporin, have met evidence-based standards.

Langerhans cells and their role in oral mucosal diseases

Dendritic cells are arguably the most potent antigen-presenting cells and may be the only cells capable of initiating the adaptive immune response. The epithelial residents of dendritic cells are Langerhans cells, which serve as the "sentinels" of the mucosa, altering the immune system not only to pathogen entry but also of tolerance to self antigen and commensal microbes. Oral mucosal Langerhans cells are capable of engaging and internalizing a wide variety of pathogens and have been found responsive to nickel in patients with nickel allergies, oral Candida species, oral lichen planus, lichenoid drug eruptions, graft versus host diseases, periodontal diseases median rhomboid glossitis, human immunodeficiency virus infection, hairy leukoplakia of the tongue, and oral squamous cell carcinoma. Review focuses on the role of antigen-presenting cells in particular Langerhans cells to better understand the mechanisms underlying immune responses. In this review, comprehensive detail about mucosal diseases has been compiled using the PubMed database and through textbooks.

The Herpes simplex virus gene Pol expressed in herpes-associated erythema multiforme lesions upregulates/activates SP1 and inflammatory cytokines

BACKGROUND/AIMS

Herpes-simplex-virus-associated erythema multiforme (HAEM) is characterized by lesional skin expression of the viral protein Pol and localized inflammation. The objective of this study is to examine the mechanism whereby Pol induces localized inflammation.

METHODS

A431 cells transfected with Pol or an empty vector and lesional skin from HAEM or drug-induced erythema multiforme patients were examined for expression of the transcription factor SP1 and SP1-regulated genes by immunoblotting, immunohistochemistry and immunofluorescence.

RESULTS

SP1, TGF-beta, p21(waf1) and Hsp27 were upregulated in A431 cells transfected with Pol but not the empty vector. Expression was further increased by exposure to IFN-gamma. Pol+ HAEM lesional skin expressed SP1, Hsp27, TGF-beta and p21(waf1). Normal skin and drug-induced erythema multiforme lesional skin were negative.

CONCLUSION

The data indicate that Pol activates SP1, causing upregulation of SP1 target genes (notably TGF-beta) involved in localized inflammation. Upregulation is potentiated by IFN-gamma.

Enzyme-linked immunosorbent assay for detection of peptide-specific human antidesmoplakin autoantibodies

BACKGROUND

Autoantibodies directed against desmoplakin (Dp) I and II have recently been characterized in a subset of patients with severe erythema multiforme (EM), a recurrent inflammatory skin disease with a broad spectrum of clinical manifestations. These autoantibodies recognize a peptide epitope localized within the extreme end of the carboxy terminal domain of Dp responsible for the assembly of keratin filaments to the desmosomal plaque. Using dot blot analysis with overlapping synthetic peptides, the binding epitope YSYSYS has been identified.

OBJECTIVES

To establish an enzyme-linked immunosorbent assay (ELISA) for detection of peptide-specific anti-Dp autoantibodies in sera of patients with EM.

METHODS

A synthetic peptide containing the respective amino acid sequence was used as matrix for ELISA plates. Serum samples from patients with known EM and peptide-specific anti-Dp autoantibodies verified by immunoblotting, immunoprecipitation and epitope mapping were used.

RESULTS

Establishing an index value of 42.0, 25 of 25 serum samples from five patients with peptide-specific anti-Dp autoantibodies were positive in the ELISA. From control sera, none of 31 bullous disease sera and only one (1.2%) of 83 normal human sera were positive.

CONCLUSIONS

These data show that the ELISA presented in this study represents a sensitive and highly specific tool for the detection of peptide-specific anti-Dp autoantibodies in patients with EM.

Numerical, morphological and phenotypic changes in Langerhans cells in the course of murine graft-versus-host disease

BACKGROUND

In the course of graft-versus-host disease (GVHD) or diseases that histologically mimic GVHD (e.g. toxic epidermal necrolysis, Stevens-Johnson syndrome), it is known that epidermal Langerhans cells (LCs) are depleted from the epidermis. However, the mechanism and significance of LC depletion is not well known.

OBJECTIVES

To investigate the numerical, morphological and phenotypic changes in LCs and apoptosis of LCs in the course of GVHD using a non-irradiated mouse GVHD model.

METHODS

BALB/c nu/nu mice and C57BL/6 mice were used as recipients and donors, respectively. Recipient mice were injected with T-cell-enriched donor spleen cells. Skin samples were harvested at various times after the inoculation. The numerical and morphological changes were examined by an immunofluorescence study of epidermal sheets. Apoptosis was studied by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling method and flow cytometric analysis using annexin V. Phenotypic change was studied by flow cytometric analysis of epidermal cell suspensions. The mixed epidermal cell lymphocyte reaction (MELR) was performed to examine functional changes in the epidermal cells.

RESULTS

Five days after inoculation, a graft-versus-host reaction occurred. Epidermal LCs began to decrease from the sixth day. On the fifth day, the LCs became larger and had prominent dendrites. Immediately before the LCs began to decrease, many LCs became round in shape, with scanty dendrites. LC apoptosis was not observed in the epidermis either on the fifth or seventh day. Phenotypically, the expression of CD40, CD80, CD86 and major histocompatibility complex class II antigen on the LCs was upregulated on the fifth and seventh day. Epidermal cells from GVHD mice showed an increased allostimulatory capacity in the secondary MELR.

CONCLUSIONS

These results suggest that at early GVHD onset, most LCs may not undergo apoptosis in the epidermis but are phenotypically activated, resulting in further activation of alloreactive T cells and aggravation of the disease.

Disseminated granuloma annulare following erythema multiforme minor

A 44-year-old woman presented with erythema multiforme minor followed by disseminated granuloma annulare 4 weeks later. The patient was not taking any medication and had no history of herpes simplex infection. Involvement of a delayed-type hypersensitivity reaction in the pathogenesis of these two well known disorders, as suggested by immunological investigations, may explain their concurrence in our patient. The substitution of the erythema multiforme minor lesions by an eruption of disseminated granuloma annulare at the same sites suggests the possibility of a Koebner phenomenon or an isotopic response.

Herpes simplex virus associated erythema multiforme (HAEM) is mechanistically distinct from drug-induced erythema multiforme: interferon-gamma is expressed in HAEM lesions and tumor necrosis factor-alpha in drug-induced erythema multiforme lesions

Erythema multiforme follows administration of several drugs or infection with various agents, including herpes simplex virus, a syndrome designated herpes simplex virus associated erythema multiforme. Lesional skin from 21 of 26 (81%) herpes simplex virus associated erythema multiforme patients was positive for herpes simplex virus gene expression as evidenced by reverse transcriptase-polymerase chain reaction with primers for DNA polymerase and/or immunohistochemistry with DNA polymerase antibody. Reverse transcriptase-polymerase chain reaction and immunohistochemistry studies indicated that herpes simplex virus associated erythema multiforme lesional skin from 16 of 21 (76%) DNA polymerase positive herpes simplex virus associated erythema multiforme patients was also positive for interferon-gamma, a product of T cells involved in delayed-type hypersensitivity (p < 0. 0001 by Pearson correlation coefficient). Interferon-gamma signals were in infiltrating mononuclear cells and in intercellular spaces within inflammatory sites in the epidermis and at the epidermis/dermis junction. Herpes simplex virus lesional skin was also positive for DNA polymerase [five of five (100%)] and interferon-gamma [four of five (80%)], but lesional skin from drug-induced erythema multiforme patients was negative. Lesional herpes simplex virus associated erythema multiforme keratinocytes also stained with antibody to transforming growth factor-beta [14 of 23 (61%)] and cyclin-dependent kinase inhibitor waf [12 of 18 (67%)]. Staining was also seen in keratinocytes from herpes simplex virus lesions [five of five (100%)], but not in normal skin. By contrast, staining with antibody to tumor necrosis factor-alpha, another pro-inflammatory cytokine, was seen in seven of 11 (64%) drug-induced erythema multiforme patients, but not in herpes simplex virus or herpes simplex virus associated erythema multiforme patients, and lesional keratinocytes from drug-induced erythema multiforme patients were negative for transforming growth factor-beta and cyclin-dependent kinase inhibitor waf. We interpret the data to indicate that herpes simplex virus associated erythema multiforme pathology includes a delayed-type hypersensitivity component and is mechanistically distinct from drug-induced erythema multiforme.

Molecular mechanisms of CD8+ T cell-mediated delayed hypersensitivity: implications for allergies, asthma, and autoimmunity

Delayed-type hypersensitivity (DTH) is defined as the recruitment of T cells into tissues to be activated by antigen-presenting cells to produce cytokines that mediate local inflammation. CD8+ T cells are now known to mediate DTH responses in allergic contact dermatitis, drug eruptions, asthma, and autoimmune diseases. This inflammatory effector capability of CD8+ cytotoxic T cells was previously poorly recognized, but there is now considerable evidence that these diseases may be mediated by CD8+ DTH. The difference between CD8+ T cells and CD4+ T cells mediating DTH relates to the molecular mechanisms by which antigens are processed and presented to the T cells. Antigens external to the cell are phagocytosed and processed for presentation on MHC class II molecules (eg, HLA-DR) to CD4+ T cells. In contrast, internal cytoplasmic antigens are processed by the endogenous pathway for presentation on MHC class I molecules (eg, HLA-A, -B, and -C) to CD8+ T cells. External allergens can also enter the endogenous pathway to be presented to CD8+ T cells. These include many contact sensitizers, chemical and protein respiratory allergens, viral antigens, metabolic products of drugs, and autoantigens. The resulting CD8+ T-cell response explains the role of CD8+ T-cell DTH mechanisms in allergic contact dermatitis, asthma, drug eruptions, and autoimmune diseases.

Erythema multiforme associated human autoantibodies against desmoplakin I and II: biochemical characterization and passive transfer studies into newborn mice

The demonstration of circulating autoantibodies directed against the constitutive desmosomal plaque proteins desmoplakin (dp) I and II in mucocutaneous lesions in a subset of patients with erythema multiforme major, suggests that humoral immune mechanisms may play a role in the pathogenesis of this severe skin disease. In this study we identified a specific peptide sequence--YSYSYS--representing an antigenic binding site for the human autoantibodies. This epitope is localized at the extreme carboxy terminal domain of dp thought to be responsible for the assembly of keratin filaments with desmosomes. To test the possibility whether these antibodies may exert any pathologic effects in vivo, human autoantibodies were affinity purified on a corresponding synthetic peptide matrix and peptide-specific antibodies were raised in rabbits. After repeated subcutaneous injections into newborn mice, affinity-purified human autoantibodies and anti-peptide rabbit IgG were detected on desmosomal plaques of keratinocytes overlying the injection site. Histologic and electron microscopic examinations showed hydropic degeneration of basal and suprabasal keratinocytes, dyskeratosis, signs of suprabasal acantholysis, and keratin filaments detached from the desmosomal plaques clumping around the nucleus. We demonstrate that autoantibodies are directed to an epitope within a dp domain crucial for the interaction of keratin filaments with desmosomes, and, when injected subcutaneously into newborn mice, produce pathologic changes. These findings imply that autoantibodies to dp could impair the function of desmosome-keratin filament complexes suggesting a pathogenic role in vivo.

Quantitative immunohistochemical differences in Langerhans cells in dermatitis due to internal versus external antigen sources

Cutaneous hypersensitivity reactions can develop against antigens delivered through the epidermis (contact dermatitis) or through the blood vessels (e.g., drug eruptions). On routine histology alone, it is not always possible to determine the route of the antigen. Langerhans cells (LC) are the main antigen-presenting cells in contact dermatitis. Dermal dendrocytes (DC) are antigen-presenting cells and may be involved in dermal reactions. We tested the hypothesis that there is a difference between dermatitis due to external and internal antigen sources with regard to the number or function of LC and DC. In 85 cases of dermatitis, numbers of S100 and HLA-DR reactive cells per linear millimetre of epidermis were counted. The amount of epidermal spongiosis was evaluated qualitatively. In 35 cases, the number of DC per mm2 (as defined by Factor XIIIa expression) was evaluated. The patients were then divided into two groups based on whether the final clinical evaluation considered the dermatitis to be secondary to an external (35 cases) or internal antigen (50 cases). Dermatitis due to external antigens had significantly more LC/mm and more frequent HLA-DR expression than dermatitis due to internal antigens, mean +/- SEM; 21.2+/-2.04 vs. 9.1+/-1.02 (p<0.00001) and 16.3+/-2.49 vs. 6.0+/-0.92 (p=0.0001), respectively. Spongiosis was more marked in external antigen cases. DC were more numerous in internal than in external antigen cases, but the differences were not statistically significant. In our model, determination of numbers of LC/mm is the variable with the highest power to discriminate between internal and internal sources. Quantification of HLA-DR+ LC and degree of spongiosis provide little additional discriminatory power.

An erythema multiforme-like eruption caused by exposure to 1-chloromethylnaphthalene

A young male patient developed an erythema multiforme-like eruption following an accidental exposure to 1-chloromethylnaphthalene (1-CMN). In addition to the skin lesion, he suffered from liver involvement and tear insufficiency. Positive results of a patch test with 1-CMN and an in vitro lymphocyte transformation test suggested that direct exposure of the skin to chemical compounds was the probable cause of his symptoms.

HLA typing in patients with ocular manifestations of Stevens-Johnson syndrome

BACKGROUND

Stevens-Johnson syndrome (SJS) is an acute, self-limited, inflammatory disorder of the skin and mucous membranes. With ocular involvement, SJS has been associated with the class I human leukocyte antigen (HLA)-Bw44. This study examined HLA class II associations in patients with SJS with ocular involvement to help identify possible molecular genetic mechanisms underlying disease susceptibility/resistance.

METHODS

Twenty-three white patients with ocular complications secondary to SJS had HLA class II typing performed using polymerase chain reaction-based molecular techniques. Genotype frequency was compared with results obtained from 175 control subjects.

RESULTS

HLA-DQB1*0601 was present in four (17%) patients with SJS and in five (3%) control subjects (P < 0.05; relative risk = 7.2). There was no association with HLA-DQB1*0301, which previously has been been strongly associated with recurrent erythema multiforme. None of the class II antigens tested appeared to offer a protective effect against the development of disease.

CONCLUSION

HLA-DQB1*0601 was found in a significantly disproportionate number of white patients with SJS and ocular complications. The presence of this allele may confer an increased risk for the development of SJS with ocular complications and provides further evidence for an underlying immunogenetic susceptibility to the development of this disease.

Antigen processing: the gateway to the immune response

The T-lymphocyte response to an antigen is governed by the source of that antigen and the way in which it is processed. Before recognition by T lymphocytes, proteins must be degraded to peptides by antigen-presenting cells. The peptides are then presented on major histocompatibility complex (MHC) molecules for recognition by the T cells. Antigens arising outside the cell (e.g., bacteria) are phagocytosed and processed by the exogenous pathway for presentation on MHC class II molecules (e.g., DR) to CD4+ cells. Antigens derived from the cytoplasm (e.g., viral proteins) are processed by the endogenous pathway for presentation by MHC class I molecules (e.g., HLA-A, -B, -C) to CD8+ cells. The response to a hapten or drug is a function of the antigen processing pathway and is determined by its chemical properties. Antigen processing also governs the T-cell response to pathogens, vaccines, and autoimmune conditions.

Autoantibodies to desmoplakin I and II in patients with erythema multiforme

Erythema multiforme (EM) represents a syndrome of chronic recurrent inflammatory skin disease. Depending on the severity and extent of skin and mucosal involvement, it is defined either as EM minor or EM major. In this study we demonstrate the presence of autoantibodies (aAbs) against desmoplakin I and II, two major proteins of the desmosomal plaque, in six of six patients with the severe variant of EM, EM major. Light microscopic studies of lesional skin and mucous membranes localized in vivo bound immunoglobulin G (IgG) in a dotted desmosomal pattern along the cytoplasmic membranes of keratinocytes. By immunoelectronmicroscopy, in vivo bound IgG was confined to the desmosomal plaques. These findings were confirmed by indirect immunolocalization studies that demonstrated the presence of IgG aAbs in the serum of patients during active disease. These aAbs did not only bind to desmosomal plaques of epithelial cells where they colocalized with defined murine monoclonal antibodies directed against desmoplakin I and II, but also labeled the intercalated discs of myocardial cells. Biochemical characterization of circulating IgG aAbs revealed desmoplakin I and II as actual target autoantigens. By passive transfer of serum into newborn mice, in vivo binding of serum aAbs to keratinocytes was shown. The findings presented in this study imply a humoral immune response in certain patients with EM major and indicate a potential pathogenetic role of aAbs against desmoplakin I and II in this disease.

Predominance of epidermal CD8+ T lymphocytes in bullous cutaneous reactions caused by beta-lactam antibiotics

The phenotype and functional characteristics of skin-infiltrating lymphocytes in beta-lactam antibiotic-induced vesiculobullous exanthemas were studied in vivo and in vitro. Immunohistochemical analysis demonstrated that CD8+ T lymphocytes were the predominant epidermal T-cell subset in these reactions. Epidermal T lymphocytes were isolated and expanded for in vitro studies. Fluorescence-activated cell sorter analysis showed the majority of epidermal T cells to be CD3+, T-cell receptor alpha/beta+, CD4-, CD8+, and HLA-DR+, which correlated with the predominance of epidermal CD8+ T lymphocytes found in situ. Three CD8+ epidermal T-cell clones derived from cutaneous lesions proliferated in response to penicillin-pulsed autologous antigen-presenting cells but not allogeneic antigen-presenting cells, indicating that those clones were antigen and major histocompatibility complex specific. All T-cell clones produced significant amounts of interleukin-2, interferon-gamma, and granulocyte-macrophage colony-stimulating factor. Additionally, the T-cell clones displayed cytotoxicity against epidermal cells in lectin-mediated cytotoxicity and against B-cell lines in T-cell receptor-triggered cytotoxicity. These data demonstrate the presence of epidermal drug-specific CD8+ T cells in bullous drug reactions. Because these CD8+ T cells have a cytotoxic potential, they may contribute to the necrosis of keratinocytes associated with drug-induced blister formation.

Langerhans cells: structure, function and role in oral pathological conditions

Langerhans cells (LCs) are dendritic bone marrow derived cells situated suprabasally in most stratified squamous epithelia, such as the epidermis and the epithelium of oral mucosa, including the gingiva. Langerhans cells are thought to act as antigen-presenting cells (APC) during induction of immune responses. The exact role of Langerhans cells in the oral mucosa is not fully understood although several investigations suggest that these cells are involved in reactions to antigen challenge under both normal and pathological situations. In this paper the structure, phenotypic markers and derivation of Langerhans cells are reviewed. In view of recent findings, the immunological characteristics and the implications of Langerhans cells in pathologic oral reactions are discussed.

Erythema multiforme: pathomechanism of papular erythema and target lesion

Skin lesions of erythema multiforme show time-dependent changes from early papular erythema to the late target lesion which consists of a peripheral elevated erythematous area and a central depressed area. We investigated the pathomechanism of erythema multiforme, by examining the papular erythema and target lesion separately. In the early papular erythema, a small number of polymorphonuclear leukocytes and nuclear debris were seen intermingled with mononuclear cells around the slightly swollen blood vessels, on which immunoglobulin and complement components were deposited. Circulating immune complex levels were occasionally elevated. Sera from the patients generated high levels of reactive oxygen species and nitroblue tetrazolium test revealed positive reaction on the infiltrating cells around the blood vessels. These findings suggest that the papular erythema develops via incomplete type III allergic reaction, followed by damage through reactive oxygen species. In the target lesion, the activity of histamine-N-methyltransferase, which is the major histamine-degrading enzyme, was markedly decreased in the peripheral elevated erythematous area and it was recovering in the central clearing area. ICAM-1 and HLA-DR antigens were expressed on the surfaces of the keratinocytes. An increased number of epidermal Langerhans cells and CD4 cell infiltration were observed in the peripheral elevated erythematous area, while a decreased number of epidermal Langerhans cells and CD8 cell infiltration in the central depressed area were observed. These findings suggest that impaired histamine metabolism and cellular allergic reactions play important roles in the development of the target lesion.

Prurigo pigmentosa: role of ICAM-1 in the localization of the eruption

Immunohistochemical studies were carried out on the skin lesions of two cases of prurigo pigmentosa. There was a predominance of CD4+ cells in the dermal infiltrate, whereas those lymphocytes in the epidermis were mainly CD8+ cells. The majority of dermal and epidermotropic lymphocytes showed an intense expression of lymphocyte function-associated antigen 1 (LFA-1). The number of CD1+ cells was increased in the epidermis. There was intense expression of ICAM-1 by keratinocytes in the erythematous papules. Focal expression of ICAM-1 was still observed in the residual pigmented areas and could explain the recurrence of the lesions at these sites.

HLA DQB1*0301 allele is involved in the susceptibility to erythema multiforme

Erythema multiforme (EM) is an acute, episodic inflammatory disorder of the skin and mucous membranes of various etiology that could be related to immunologic hypersensitivity response. EM has been previously reported to be associated with serologically defined HLA-DRw53 and DQw3 antigens. In this report, we reevaluate the role of HLA class II alleles in EM manifestations. With use of the polymerase chain reaction, followed by sequence-specific oligonucleotide hybridization, 35 unrelated Caucasian EM patients and 80 randomly selected healthy subjects were studied, and the DRB3, DRB4, DQA1, and DQB1 alleles were analyzed. The comparison of frequencies of these alleles indicates that (i) susceptibility to EM disease is more associated with the HLA-DQ than the HLA-DR subregions and (ii) that the DQB1*0301 is the most frequent allele among EM patients. Sixty-six percent of the patients had the DQB1*0301 allele compared to 31% of the controls (RR = 4.1; p less than 0.001). An even stronger DQB1*0301 association was found in the patient group with herpes-associated EM (76%; RR = 6.5; p less than 0.001). Our data demonstrate a clear association between an HLA-DQB1 allele and susceptibility to EM.

Immunohistochemistry of cutaneous graft-versus-host disease after allogeneic bone marrow transplantation

Graft-versus-host disease (GVHD) is an immunologically mediated disease occurring most frequently after allogeneic bone marrow transplantation. The aim of this study was to evaluate the contribution of immunohistochemistry in the diagnosis of cutaneous GVHD. Patients transplanted for either leukemia or beta-thalassemia were included in the study. Skin lesions of acute and chronic GVHD were examined both by direct immunofluorescence to detect immunoglobulin deposits and by an avidin-biotin-peroxidase complex technique to evaluate the inflammatory cell infiltrate. Epidermal and dermal fluorescent bodies (IgG and IgM) were frequently found in both acute and chronic GVHD. Most of the infiltrating cells were CD3+ T lymphocytes, with CD8+ cells representing the major cell population invading the epidermis both in acute GVHD and in chronic lichenoid GVHD. A small proportion of the dermal cells were CD14+ macrophages; no B cells were detected. HLA-DR, but not HLA-DQ antigens, were variably expressed by keratinocytes in all cases of acute GVHD and in chronic lichenoid GVHD. KL-1, a monoclonal antikeratin antibody specific for the 56.5 KD acidic polypeptide usually present in suprabasal keratinocytes, stained all epidermal layers, including the basal layer. Langerhans cells were dramatically reduced in number in the epidermis of both acute and chronic lichenoid GVHD. It is concluded that immunohistologic analysis may be supportive in the diagnosis of acute and early chronic lichenoid cutaneous GVHD.

Cicatricial pemphigoid and erythema multiforme

Cicatricial pemphigoid (CP) and erythema multiforme (EM) are bullous diseases that involve the skin and mucous membranes including the conjunctiva. Of all the bullous diseases, CP and EM not only involve the conjunctiva most frequently but also cause the most severe conjunctival disease. A chronic, progressive disease, CP is characterized by shrinkage of the conjunctiva, symblepharon, entropion, trichiasis, dry eye, and finally reduced vision from corneal opacification. It is primarily a disease of the elderly that affects more women than men and is characterized by blisters or bullae in a subepithelial location and immunoglobulins and complement bound to the basement membrane zone of skin and mucous membranes including the conjunctiva. Circulating antibodies to the basement membrane zone can be demonstrated occasionally. Treatment includes artificial tears, topical antibiotics, correction of entropion and trichiasis, therapeutic soft contact lenses, and systemic immunosuppressive therapy including corticosteroids. An acute, generally self-limited, inflammatory disorder of the skin and mucous membranes, EM occurs primarily in young, healthy individuals. The most frequent precipitating factors are (1) drugs and (2) infections caused by Mycoplasma pneumoniae and herpes simplex. Conjunctival involvement ranges from a mild catarrhal conjunctivitis which terminates without sequelae to membranous conjunctivitis which may heal leaving scarring, symblepharon, and even ankyloblepharon. Histopathologic findings include subepithelial bullae and perivascular mononuclear cell infiltrates. Patients with EM have circulating immune complexes and immunoreactant deposition in the blood vessel walls of the dermis. After the acute episode has subsided, they may require artificial tears, topical antibiotics, correction of entropion and trichiasis, therapeutic soft contact lenses, tarsorrhaphy, and mucous membrane grafts.

Chronic actinic dermatitis: an immunohistologic and photobiologic study

Photobiologic, histologic, and immunohistochemical findings in 14 patients with chronic actinic dermatitis were compared. Grading of routine histologic features of involved skin demonstrated a spectrum of abnormalities ranging from changes resembling chronic dermatitis to those of cutaneous T cell lymphoma. Immunohistochemical staining showed dermal infiltrates to consist predominantly of T lymphocytes, with a significant trend toward lower CD4+/CD8+ ratios in cases with more florid histologic findings. Circulating CD4+/CD8+ cell ratios were normal in five patients and reduced in one patient. Photosensitivity extending to wavelengths longer than 340 nm was detected in eight patients, but the spectrum of photobiologic abnormality did not appear to correlate with either grading of histologic severity or variation in T cell subsets in lesional skin.

Erythema multiforme in children: unusual clinical features with seasonal occurrence

Eighty-six cases of erythema multiforme (EM) were studied based on the distribution of skin lesions. Twenty-nine patients had distinct facial skin lesions as well as lesions on the extremities (Group A) and 57 patients had skin lesions only on the extremities (Group B). Patients in Group A were younger than those in Group B; the average ages being 7.5 and 25.2 years, respectively. In Group A, the disease occurred mainly in winter, while, in Group B, it began most frequently in summer. Preceding ulcerated pernio was seen in 11 patients of Group A, but only one of Group B. Histopathologically, both groups are compatible with a diagnosis of EM, although the seasonal occurrence of facial involvement in Group A may suggest a specific etiological relationship to cold.

Controversy: are systemic steroids indicated in the treatment of erythema multiforme?

The treatment of erythema multiforme major with systemic steroids became established during the 1950s. Recently, two retrospective case reviews comparing steroid-treated and nonsteroid-treated groups of patients with erythema multiforme found that these agents may be associated with complications. As a result, many clinicians have become uncertain as to the appropriate therapy of this disease entity. We successfully treated the condition with steroids in two children and one adolescent. The controversy over the potential efficacy of such therapy for erythema multiforme persists, however.

Episodic conjunctival inflammation after Stevens-Johnson syndrome

The authors studied the histopathologic, ultrastructural, and immunopathologic characteristics of conjunctiva from patients with Stevens-Johnson syndrome (SJS). A small subset of SJS patients with recurrent conjunctival inflammation unassociated with external factors such as lid margin keratinization, sicca syndrome, trichiasis, or entropion was identified. The ultrastructural and immunopathologic characteristics of the conjunctiva from these patients were distinctly different from those of the conjunctiva from SJS patients without recurrent conjunctivitis, and suggested an active, immunologically mediated inflammation. Vasculitis or perivasculitis, immunoreactant deposition in vessel walls, vascular basement membrane disruption, thickening, and reduplication, and a preponderance of helper T-lymphocytes, macrophages, and Langerhans' cells were the notable distinguishing features in those patients with recurrent conjunctival inflammation. This rare clinical syndrome may represent the ocular counterpart to recurrent dermal or oral mucosal erythema multiforme.

Comparison of different methods for enumeration of Langerhans cells in vertical cryosections of human skin

We have quantified Langerhans cells (LC) in cryosections of normal human skin and lesional skin from patients with atopic eczema and psoriasis vulgaris using six different methods. The results from the different methods varied considerably and were sometimes contradictory, for example when LC numbers in psoriatic skin were compared with those in normal skin. Thus, in addition to the staining technique used and the selection of the dendritic cell type to be counted, the enumeration method used can also influence the quantitation of LC in normal and pathological skin.

Drug-induced skin reactions and acute cutaneous graft-versus-host reaction: a comparative immunohistochemical study

Skin biopsies from eight patients with drug-induced dermatitis have been compared with skin biopsies from 16 patients developing skin lesions (acute graft versus host-reaction and/or drug-induced reaction) after bone marrow transplantation. Biopsies were investigated using immunohistochemistry and several monoclonal antibodies. Morphological and immunohistochemical patterns in skin biopsies of both groups were very similar. The only difference seen was a reduced number of epidermal Langerhans cells with poorly developed dendrites in skin biopsies taken from patients who underwent bone marrow transplantation. If the latter finding is due to the cytotoxic drug regimen administered before bone marrow transplantation, as previously stated, we doubt the usefulness of skin biopsies in the differential diagnosis of acute graft-versus-host reaction and drug-induced skin lesions.

An immunopathological study of herpes-associated erythema multiforme

Any pathogenetic mechanism proposed for erythema multiforme (EM) must account for the prominent mononuclear cell infiltrate in the skin lesions. The purpose of this study was to characterize immunopathologically, with monoclonal antibodies to human leukocyte antigens, the inflammatory cells in early target lesions of recurrent herpes-associated EM. Cryostat sections of snap-frozen skin biopsies were studied by the avidin-biotin immunoperoxidase technique with use of the following monoclonal antibodies: anti-HLA-DR, anti-Leu M5, anti-Leu 4 + 5b, anti-Leu 3a + 3b, anti-Leu 2a, anti-Leu 14, and anti-Leu 6. The dermal mononuclear inflammatory infiltrate in the EM biopsies consisted of monocyte-macrophages and T-lymphocytes, with both helper and suppressor T cells present. Both the dermal inflammatory infiltrate and the overlying keratinocytes were strongly HLA-DR positive. No definite alteration of Langerhans cell number or distribution was noted. These findings are consistent with the characteristics seen in cell-mediated immune reactions in the skin and point to this as a likely immune mechanism for the tissue damage of EM.

Interface dermatitis in patients with the acquired immunodeficiency syndrome

We report twenty-five patients with the acquired immunodeficiency syndrome (AIDS) and interface dermatitis. Patients with AIDS and interface dermatitis had numerous opportunistic and herpetic infections. Nearly all patients were receiving at least one medication prior to the development of their rash and many were clinically thought to have a drug eruption. When compared to skin biopsy specimens from non-AIDS patients with drug eruptions, specimens from patients with AIDS and interface dermatitis demonstrated a greater degree of vacuolar change, the frequent occurrence of necrotic keratinocytes, often in clumps, and the absence of eosinophils and polymorphonuclear leukocytes in the dermal infiltrates. Histologic and clinical features of our patients with AIDS and interface dermatitis are presented and contrasted with other interface dermatitides. Systemic and cutaneous immune abnormalities in patients with AIDS may be relevant to the pathogenesis of this interface process.

Immunohistology of pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica. Evidence for their interrelationship with lymphomatoid papulosis

Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica are idiopathic, papular eruptions that exhibit certain clinicopathologic similarities to each other and to lymphomatoid papulosis. In order to determine if these disorders are also similar immunologically, we studied the immunopathology of five biopsy specimens from three cases of pityriasis lichenoides et varioliformis acuta and three biopsy specimens from three cases of pityriasis lichenoides chronica. We then compared them to our prior immunohistologic study of nine cases of lymphomatoid papulosis. Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica both exhibited a dermal and epidermal infiltrate of CD4+ and CD8+ T cells expressing activation antigens. These were admixed with numerous macrophages. The lesional epidermis was diffusely human lymphocyte antigen (HLA)-DR+ and contained decreased CD1+ dendritic cells. Endothelial cells were also HLA-DR+. Cells bearing the phenotypes of B cells, follicular dendritic cells, or natural killer/killer cells were essentially absent. Except for the lack of large atypical cells, the results resembled those described previously for lymphomatoid papulosis. These findings indicate that pityriasis lichenoides chronica, pityriasis lichenoides et varioliformis acuta, and lymphomatoid papulosis share several immunohistologic features. Together with certain clinicopathologic similarities, they are consistent with the hypothesis that these three disorders are interrelated.

Quantitative studies of the fate of epidermal Langerhans cells after X-irradiation of guinea-pig and mouse footpad skin

Langerhans cell numbers, morphology and distribution were observed in cross sections of footpad epidermis at intervals from 1 to 28 days after exposure of the hind feet of CBA/H mice or albino guinea-pigs to a single absorbed dose of 20 Gy (2000 rad) of X-rays. In mice, the number of Langerhans cells reactive with anti-macrophage F4/80 monoclonal antibody steadily declined by approximately 85% within 10 days after irradiation, consistent with previous studies, in which Langerhans cells were identified in epidermal sheets by ATPase activity or presence of Birbeck granules. Remaining Langerhans cells were exceptionally dendritic. Very few Birbeck granule-containing cells were found in murine popliteal lymph nodes before or after irradiation but damaged cells were present in superficial strata of irradiated epidermis. The morphology and number of epidermal F4/80-positive cells approached normal by 15 days after irradiation. In guinea-pigs, gradual suprabasal movement and loss of rounded, ATPase-positive Langerhans cells from the epidermis were detectable from 5 to 20 days after irradiation but the magnitude of the cell loss and redistribution was partially obscured by the simultaneous appearance of clusters of replacement Langerhans cells in the basal layer and by keratinocyte hyperplasia.