Epidermal Langerhans cells, dermal dendritic cells, and keratinocytes in viral lesions of skin and mucous membranes: an immunohistochemical study

Dermatologists' Impressions of Spontaneously Regressing Verruca Plana Histopathology

ABSTRACT

Verruca plana in its regressing phase exhibits clinical and histological features distinct from classic verruca plana, but the ways in which these features should inform treatment plans are still under investigation. We conducted a retrospective single-center analysis of 25 patients with features of classic verruca plana, or plane warts, who exhibited self-remission within 4 weeks of skin biopsy. Measures included lesion sites, clinical findings preceding regression, and histological analysis. Histological analysis involved review by 2 dermatologists followed by impressions given by 4 board-certified dermatologists who were blinded to the clinical characteristics of the patients. Histopathological findings of regressing plane warts showed superficial perivascular infiltration (96%), spongiosis and exocytosis (84%), basal vacuolization (64%), parakeratosis (64%), apoptotic keratinocytes (60%), and lichenoid infiltration (44%). These findings were more compatible with the histological patterns of pityriasis lichenoides, lichen planus, and spongiotic eczema, rather than classic verruca plana. This suggests that regressing verruca plana may be included in the differential diagnosis of lesions exhibiting a lichenoid or spongiotic reaction, and observation may be a favorable treatment plan in these patients.

[Amoxicillin-induced skin rash sparing a plaque of erythema migrans: Renbök phenomenon: Case report and literature review]

INTRODUCTION

Renbök phenomenon describes the inhibition of a lesion when a different one appears. We describe the first case of Renbök phenomenon occurring in a context of erythema migrans (EM) spared by an amoxicillin-induced skin rash and we also present a literature review.

CASE REPORT

A 60-year-old patient was treated with amoxicillin for EM on the right knee and subsequently developed generalized erythema as a result of an antibiotic-induced skin rash, with sparing of the area previously affected by EM. Renbök phenomenon was diagnosed.

DISCUSSION

In 1981, Cochran et al. first described a maculopapular drug reaction, which spared the sites of previous X irradiation for a tumor. Since then, nearly 40 cases have been reported, mostly describing patient with alopecia areata of the scalp with hair growth within plaques of psoriasis. One of the mechanisms suggested is a role played by cytokine cross-regulation in competition among distinct immune responses.

CONCLUSION

We report the first case of Renbök phenomenon involving EM spared by a drug reaction. This phenomenon provides an insight into inflammatory response competition within a single patient.

Suppression of the CD8 T cell response by human papillomavirus type 16 E7 occurs in Langerhans cell-depleted mice

Human papillomavirus (HPV) is an epitheliotropic virus that is the primary causal agent for cervical cancer. Langerhans cells (LC) are skin antigen presenting cells that are reduced in number in HPV-infected skin. The aim of this study was to understand the immune-modulatory effects of HPV16 E7 on LC and on the CD8 T cell response to a skin-expressed antigen. To test this, HPV16 E7 was expressed in mouse skin keratinocytes with the model antigen ovalbumin (Ova). Similar to what is observed in HPV-infected human skin, LC numbers were significantly reduced in E7-expressing mouse skin. This shows that expression of the E7 protein alone is sufficient to mediate LC depletion. Expression of E7 with Ova in keratinocytes strongly suppressed the Ova-specific CD8⁺ T cell response in the skin draining lymph node. When tested in LC-ablated mice, the CD8 T cell response to skin-expressed Ova in control mice was not affected, nor was the T cell response to Ova restored in E7-expressing skin. These data indicate a role for E7 in regulation of LC homeostasis in the skin and in suppression of antigen specific CD8 T cell expansion, but suggest that these two effects occur independent of each other.

DOCK8 regulates lymphocyte shape integrity for skin antiviral immunity

Zhang et al. show that DOCK8-deficient T and NK cells develop cell and nuclear shape abnormalities that do not impair chemotaxis but contribute to a form of cell death they term cytothripsis. Cytothripsis of DOCK8-deficient cells prevents the generation of long-lived skin-resident memory CD8 T cells resulting in impaired immune response to skin infection.

DOCK8 mutations result in an inherited combined immunodeficiency characterized by increased susceptibility to skin and other infections. We show that when DOCK8-deficient T and NK cells migrate through confined spaces, they develop cell shape and nuclear deformation abnormalities that do not impair chemotaxis but contribute to a distinct form of catastrophic cell death we term cytothripsis. Such defects arise during lymphocyte migration in collagen-dense tissues when DOCK8, through CDC42 and p21-activated kinase (PAK), is unavailable to coordinate cytoskeletal structures. Cytothripsis of DOCK8-deficient cells prevents the generation of long-lived skin-resident memory CD8 T cells, which in turn impairs control of herpesvirus skin infections. Our results establish that DOCK8-regulated shape integrity of lymphocytes prevents cytothripsis and promotes antiviral immunity in the skin.

Wolf's Isotopic Response: Report of a Case and Review of Literature

“Wolf's isotopic response” refers to the occurrence of a new dermatosis at the site of previously healed dermatosis. A number of factors including viral, neural, vascular, and immunologic factors have been implicated in the causation of this peculiar response but none has been proven conclusively. Here, we report a case where lichen planus developed at the site of dermatofibrosarcoma protruberans that had been previously treated with surgery and radiotherapy. We also put forth a hypothesis on the genesis of isotopic response considering the above mentioned factors.

Spontaneous cervicovaginal lesions and immune cell infiltrates in nonhuman primates

Nonhuman primates, particularly rhesus macaques (Macaca mulatta), provide important model systems for studying human reproductive infectious diseases such as human immunodeficiency virus, human papillomavirus, and Chlamydia spp. An understanding of the spectrum of spontaneous cervical disease provides essential context for interpreting experimental disease outcomes in the female reproductive tract. This retrospective study characterizes the incidence of inflammatory and/or proliferative cervicovaginal lesions seen over a 14-year period in a multispecies nonhuman primate colony, focusing on rhesus macaques. The most common observations included a spectrum of lymphocytic accumulation from within normal limits to lymphoplasmacytic cervicitis, and suppurative inflammation with occasional squamous metaplasia or polyp formation. These inflammatory spectra frequently occurred in the context of immunosuppression following experimental simian immunodeficiency virus (SIV) infection. Cervical neoplasias were uncommon and included leiomyomas and carcinomas. Cervical sections from 13 representative cases, with an emphasis on proliferative and dysplastic lesions, were surveyed for leukocyte infiltration, abnormal epithelial proliferation, and the presence of papillomavirus antigens. Proliferative lesions showed sporadic evidence of spontaneous papillomavirus infection and variable immune cell responses. These results underscore the importance of pre screening potential experimental animals for the presence of preexisting reproductive tract disease, and the consideration of normal variability within cycling reproductive tracts in interpretation of cervical lesions.

Identification of an important immunological difference between virulent varicella-zoster virus and its avirulent vaccine: viral disruption of dendritic cell instruction

Virulent varicella-zoster virus (VZV) can spread in immunocompetent humans, resulting in symptoms mostly of the skin. In contrast, vaccine Oka (V-Oka), the attenuated VZV vaccine strain, only rarely causes clinical reactions. The mechanisms underlying these pathogenetic differences are unclear. In this study, we comparatively analyzed the ability of virulent VZV and V-Oka to modulate instruction of dendritic cells (DCs) by innate signals. DCs isolated from normal human skin were susceptible to infection with VZV and V-Oka. Moreover, inflammatory DCs, which play a crucial role in the stimulation of Th1 immune responses, accumulated in herpes zoster lesions. Infection of inflammatory DCs generated in vitro with virulent VZV or V-Oka resulted in upregulation of CD1c. Upon coculture with CD1c-restricted innate cells, DCs developed a mature phenotype whether infected with virulent VZV or V-Oka. Intriguingly, a striking difference was detected on the functional level. The release of IFN-gamma and IL-12, the signature cytokines of Th1 responses, was enhanced by V-Oka but blocked by virulent VZV. V-Oka and virulent VZV efficiently synergized with CD40L, eliminating the possibility that CD40 signaling was a target of VZV-associated immune evasion. Instead, virulent VZV selectively interfered with signaling through TLR2, which is known to sense VZV. Thus, virulent VZV subverts Th1-promoting instruction of human DCs by blocking TLR2-mediated innate signals that prime IL-12 production by DCs. Taken together, our results demonstrate a novel immune-evasion mechanism of virulent VZV that has been lost during the attenuation process leading to the VZV vaccine strain.

Host immune responses to cervical cancer

PURPOSE OF REVIEW

The purpose of this review is to understand the role of the host immune system in clearing the human papillomavirus (HPV) infection, strategies adopted by HPV to subvert the host immune responses and analyze the challenges to the future immunotherapeutic treatment modalities.

RECENT FINDINGS

Cervical epithelium provides a protective niche to the virus to subvert the immune responses. The absence of an inflammatory milieu in the cervix makes the resident dendritic and langerhan cells tolerogenic to HPV antigens. CD4 cells predominated in regressing cervical intraepithelial neoplasia lesions, whereas CD8 cells were dominant in invasive carcinoma. A reduced expression of T cell signaling molecule T-cell receptor zeta chain was observed in CD8 lymphocytes. Decreased numbers of NKG2D expressing natural killer and T cells were present in patients with cervical cancer and cervical intraepithelial neoplasia. Increased frequencies of CD4 CD25+ FoxP3+ T regulatory cells were observed in patients with cervical cancer. The Nrp-1+Treg showed greater suppressive activity. A network of Treg and indoleamine 2, 3-dioxygenase expressed in tumor cells facilitates immune escape of tumor cells.

SUMMARY

The HPV uses different strategies to evade immune recognition. Understanding the immune evasion mechanisms used by HPV will help in designing newer therapeutic strategies for cervical cancer.

MHC class II expression by follicular keratinocytes in canine demodicosis—An immunohistochemical study

MHC class II proteins present fragments of extra cellular antigen to stimulate CD4(+) T lymphocytes. Aim of this study was the detection of MHC class II antigens on different cutaneous cells in canine demodicosis. Histopathological and immunohistochemical examination of skin biopsies from 44 dogs with demodicosis is reported. The control group consisted of skin biopsies taken from 10 necropsied dogs without obvious skin lesions. The immunohistological assessment of the MHC class II expression revealed MHC class II proteins on different cell types of infiltrating inflammatory cells, i.e. APCs (antigen-presenting cells), macrophages, T lymphocytes and B lymphocytes. The plasma cells, however, only showed expression in 32 (73%) of 44 cases. Generally it was noticeable that most plasma cells but never all of them expressed MHC class II. Neutrophils, mast cells and eosinophils were MHC class II negative. Furthermore, in 39 biopsies (89%) from dogs with demodicosis MHC class II positive follicular keratinocytes were found. The control group did not show MHC class II expression on epithelial cells. Concerning the endothelial cells, a total of 25 biopsies (57%) showed MHC class II expression in which different vascular plexuses were affected by staining. This examination shows that MHC class II expression in the skin of dogs suffering form demodicosis is elevated. Especially the MHC class II expression by follicular keratinocytes seems to be conspicuous. We hypothesize that this is in association with the development and the maintenance of follicular inflammation.

Bcl-2-positive epidermal dendritic cells in inverted follicular keratoses but not squamous cell carcinomas or seborrheic keratoses

AIM

In our previous research, bcl-2-positive dendritic cells were seen in increased numbers in suprabasal areas of inverted follicular keratoses (IFKs) compared to seborrheic keratoses (SKs). The purpose of this study was twofold; firstly, to support that these dendritic cells are Langerhans cells and secondly, to contrast the epidermal dendritic cells in IFKs, squamous cell carcinomas (SCCs), and SKs.

METHODS

Ten IFKs and five SKs previously showing bcl-2-positive dendritic cells within the epidermis were stained with CD1a. Fifteen other IFKs were stained with CD1a alone. Ten SCCs were stained with bcl-2 and CD1a.

RESULTS

In the 10 IFKs stained with both bcl-2 and CD1a, the density of CD1a-positive cells correlated well with the density of bcl-2-positive dendritic cells; in the five SKs, the density of CD1a-positive cells was similar to that seen in IFKs but was higher compared to the density of bcl-2-positive dendritic cells in SKs (p < 0.05). The IFKs had a significantly higher number of CD1a-positive cells compared to SCCs (p < 0.01). SCCs showed bcl-2-positive cells only within the basal layer of the normal epidermis flanking the carcinomas.

CONCLUSIONS

These results suggest that there is different bcl-2 regulation of CD1a-positive cells in IFKs, SKs, and SCCs.

Immune response in cervical dysplasia induced by human papillomavirus: the influence of human immunodeficiency virus-1 co-infection - review

Human immunodeficiency virus (HIV-1) has become an important risk factor for human papillomavirus (HPV) infection and the development of HPV associated lesions in the female genital tract. HIV-1 may also increase the oncogenicity of high risk HPV types and the activation of low risk types. The Center for Disease Control and Prevention declared invasive cervical cancer an acquired immunodeficiency virus (AIDS) defining illness in HIV positive women. Furthermore, cervical cancer happens to be the second most common female cancer worldwide. The host's local immune response plays a critical factor in controlling these conditions, as well as in changes in the number of professional antigen-presenting cells, cytokine, and MHC molecules expression. Also, the production of cytokines may determine which arm of the immune response will be stimulated and may influence the magnitude of immune protection. Although there are many studies describing the inflammatory response in HPV infection, few data are available to demonstrate the influence of the HIV infection and several questions regarding the cervical immune response are still unknown. In this review we present a brief account of the current understanding of HIV/HPV co-infection, emphasizing cervical immune response.

Cutaneous T-cell lymphoma sparing resolving dermatomal herpes zoster lesions: an unusual phenomenon and implications for pathophysiology

Exclusion of cutaneous T-cell lymphoma (CTCL) by another dermatosis has not been reported. The mechanism for the epidermotropism of helper T lymphocytes in this indolent malignancy is not known. Although there is evidence that Langerhans cells (LC) play a role in the epidermotropism of lymphocytes in CTCL, clinical or in vivo support is lacking. We describe a patient with CTCL who developed herpes zoster involving the left T8 dermatome. When his CTCL became widespread after the herpes zoster healed, the previously affected areas of herpes zoster and their periphery were clinically free of lymphoma. Immunohistochemical analysis of a clinically uninvolved patch revealed absence of CD1a(+) cells in the epidermis, consistent with loss of LC in the areas spared by CTCL. There was no loss of LC in areas affected by CTCL. This is an unusual inhibition of CTCL by a prior viral infection. The loss of LC in the clinically spared skin suggests a role for LC in the epidermotropism of lymphocytes in CTCL.

Absence of intercellular adhesion molecule 1 expression in varicella zoster virus-infected keratinocytes during herpes zoster: another immune evasion strategy?

Downregulation of major histocompatibility complex (MHC) class I, MHC-II, and intercellular adhesion molecule 1 (ICAM-1) expression in infected cell lines allows some viruses to escape host immunity. In skin lesions of varicella zoster virus (VZV), MHC-II transcripts were demonstrated in keratinocytes around vesicles, but not in VZV-infected cells. Whether other immunoevasive mechanisms are present during herpes zoster (HZ) is not yet elucidated. The aim of the study was to disclose the temporal immunohistochemical expression of immune escape mechanisms during HZ. Sequential skin biopsies were performed in 5 HZ patients. VZV IE63, CD1a, CD3, CD4, CD8, CD56, CD68, L1, HLA-DR, HLA-ABC, interleukin (IL)-6, IL-10, interferon gamma (IFNgamma), tumor necrosis factor alpha (TNFalpha), and ICAM-1 expressions were assessed on frozen sections using immunohistochemistry. Controls consisted of normal skin, herpes simplex virus (HSV) skin infections, and other distinct bullous skin diseases. HLA-DR and ICAM-1 expressions were not observed in VZV- and HSV-infected keratinocytes, contrasting with their upregulation in the surrounding epidermis and inside nonviral blisters. However, HLA-ABC expressions were not inhibited in VZV-infected keratinocytes. Furthermore, the CD4/CD8 ratio remained unmodified during the infection evolution, and this ratio was variable among patients. Increased IFNgamma, TNFalpha, and IL-6 expressions were present, but IL-10 expression only increased in later stages. In contrast to in vitro MHC-I and MHC-II downregulation, VZV infection is related to MHC-II but not MHC-I expression on infected keratinocytes. The absence of ICAM-1 expression on infected keratinocytes may reduce their antigen presentation capacities to LFA-1 ligand-bearing T cells. This may represent another VZV-associated immune escape mechanism. Increased IFNgamma, TNFalpha, and IL-6 expressions suggest a TH1 profile.

Human papillomavirus molecular biology and pathogenesis

Human papillomavirus (HPV) infection is the most common sexually transmitted disease in the world and accounts for an estimated 11% of the global cancer incidence in women. HPV-16 is the most prevalent type detected in cervical cancer and along with types 18, 31, 33 and 45 has been classified as a class I carcinogen. In addition to cervical cancer, HPVs are also associated with the malignant transformation of other mucosal and skin cancers. Thus, the combination of the malignant potential of HPV and its high prevalence of infection confers to it an importance of generalized clinical and virological significance. The natural history of HPV infection with or without treatment varies from spontaneous regression to persistence. The most important mechanism for wart regression appears to be cell-mediated immunity. Cytokines released by keratinocytes or cells of the immune system may play a part in the induction of an effective immune response against HPV infection and the subsequent regression of lesions. This review discusses the molecular biology, pathogenesis and immunology of HPV infections.

Immunity to oncogenic human papillomaviruses

The establishment of human papillomavirus (HPV) infection as a major cause of several human cancer forms, notably cervical cancer, has spurred development of prophylactic and/or therapeutic HPV vaccines for prevention of cervical neoplasia. Knowledge of the immunity to HPV forms the basis for such endeavors.

METHOD

A literature review of humoral and cellular immunity to HPV. The overview on human leukocyte antigen (HLA) and cervical cancer was expanded to a formal metaanalysis, where relevant articles were located by Medline search and citation analysis and graded by preassigned quality criteria on study design.

RESULTS

The antibody response to the HPV particle is dominated by a neutralizing antibody response to a typespecific, conformationally dependent immunodominant epitope. Vaccines based on viral particles lacking the viral genome (virus-like particles, VLPs) have been highly successful in preventing and treating HPV infection in several animal model systems. In humans, the serum antibody response to VLPs is stable over time, also after the HPV infection has been cleared, resulting in HPV serology being used as a marker of cumulative HPV exposure in spite of the fact that a significant proportion of HPV-exposed subjects fail to seroconvert. More than 90% of HPV infections will clear spontaneously. The factors that determine whether an HPV infection is cleared or persists and increases the risk for cancer are not known, but cellular immunity is implicated. Several HLA class II haplotypes are associated with cervical cancer: DQw3 increases and DR13 decreases the risk for cervical cancer in general (odds ratios (OR) and 95% confidence intervals (CI): 1.25(1.15-1.37) and 0.69 (0.56-0.85), respectively); DR15 increases the risk for HPV16-carrying cancer (OR: 1.47; CI: 1.20-1.81); and DR7 may be either protective or increase the risk. Most cervical cancers have downregulated the expression of at least one HLA class I antigen, whereas class II expression is increased in infected epithelium. A Th2 cytokine profile is associated with progression to cervical cancer. HPV-antigen-specific proliferative responses have been detected in many studies, although it is not entirely clear whether these responses are HPV type specific or may be cross-reactive between HPV types. Specific cytotoxic T lymphocyte (CTL) responses were originally reported in only a minority of infected subjects, typically cancer patients, but with advancing technology, specific CTLs can be stimulated from about half of the women with HPV-carrying disease. In animal model systems, CTL responses can mediate clearance.

CONCLUSION

The antibody response to HPV is a mediator of type-specific protective immunity, which forms the basis for prophylactic vaccine candidates. The cellular immunity to HPV is implicated as an important factor in cervical carcinogenesis, but the main targets and types of responses that mediate HPV clearance are not established.

Human papillomavirus infections: epidemiology, pathogenesis, and host immune response

Human papillomaviruses (HPVs) are ubiquitous and often cause lesions on the skin that come to the attention of the dermatologist. Skin lesions, or warts, often occur on the hands or soles of the feet and can cause embarrassment or discomfort. Genital HPV infections are transmitted by sexual contact. Infections associated with some HPV types have a high risk of progressing to carcinoma. This review discusses the molecular biology and genetics of human papillomaviruses and provides an overview of the virology, pathology, clinical manifestations, and host immune response to infection.

Lymphocytes and dendritic cells in the normal uterine cervix. An immunohistochemical study

OBJECTIVE

Assessment of the appearance, distribution and numerical density of immune cell populations in the normal human uterine cervix.

STUDY DESIGN

SETTING

University Hospital Gasthuisberg.

SUBJECTS

29 healthy women undergoing total hysterectomy for non-cervical benign uterine disease.

ANALYSIS

Immunohistochemistry and morphometrical analysis on histological sections containing ectocervix, transformation zone and endocervix, using antibodies against the following antigens: HLA-DR, CD4, CD22, CD1a and CD8.

STATISTICAL ANALYSIS

Wilcoxon rank sum test.

RESULTS

Lymphocytes in the epithelial and stromal compartments are predominantly T-lymphocytes. Intraepithelial T-lymphocyte and Langerhans' cell densities and their distribution are not influenced by the menstrual cycle and are the same in both ectocervix and transformation zone.

CONCLUSION

The wide variation of T lymphocyte subpopulations and Langerhans' cell densities in the normal epithelium of the uterine cervix is stressed. We are the first to present a large and well-defined control series, which is indispensable to study the effect of smoking and other factors on the cervical immune system.

Physiology and pathophysiology of dendritic cells

Dendritic cells are antigen-presenting cells derived from the hematopoietic stem cell. The dendritic cell family includes Langerhans' cells (CD1a-positive dendritic cells of the skin), and antigen-presenting cells that are found in the lymphoreticular system and throughout the organ parenchyme. Dendritic cells play a key role in both the primary and secondary immune responses. Several studies indicate that these cells participate in antitumor immunity, tumor surveillance, graft-versus-host disease, and in the pathogenesis of clinical syndromes of unknown origin or those induced by viruses, such as the human immunodeficiency virus. Different disorders are characterized by an abnormal proliferation and accumulation of dendritic cells; for example, the Langerhans' histiocytes, which accumulate in Langerhans' cell histiocytosis. In this review the immunophenotypic, morphological, and functional characteristics of the dendritic cell family is described. The clinical and laboratory studies suggesting a unique role for these cells in various syndromes and diseases are reviewed. The Langerhans' cell histiocytoses and the malignant disorders associated with transformation of cells belonging to the dendritic cell family, are discussed.

Skin-associated lymphoid tissue in human immunodeficiency virus-1, human papillomavirus, and herpes simplex virus infections

The skin-associated lymphoid tissue is composed of keratinocytes, Langerhans cells, skin trophic T cells, and lymphatic endothelial cells of the skin. The epidermis, which is involved in many viral infections, contains all of the components needed for an effective immune response: antigen-presenting Langerhans cells, T cells, and cytokines from leukocytes and keratinocytes. There have been some recent advances in the study of the cutaneous immunology involved in infections with the human immunodeficiency virus (HIV), human papillomavirus (HPV), and herpes simplex virus (HSV). In general, viral diseases with cutaneous manifestations lead to a decline in epidermal Langerhans cell numbers, which probably reflects Langerhans cell emigration out of the epidermis and entry into regional lymph nodes, leading to Langerhans cell activation and antigen presentation to T cells. In HSV, there is a subsequent T-cell infiltration of the epidermis, composed of CD4+ cells that have both immune modulatory action and direct cytotoxic action. In HIV, where there is a systemic depletion of CD4+ cells, the epidermis is left with reduced numbers of T cells. Intradermal injection of interleukin-2, however, leads to an epidermal cellular infiltration in HIV+ individuals. In HPV-induced condyloma, intralesional interferon increases Langerhans cells and CD4+ and CD8+ cells in the skin, as well as transforming growth factor beta 1, tumor necrosis factor-alpha, pRB, and p53. Therefore, viral infections involving the epidermal immune system have certain similar characteristics, whereas other factors are unique to the infecting virus.

Facial and perioral molluscum contagiosum in patients with HIV infection. A report of eight cases

Facial and perioral molluscum contagiosum is a common and often disfiguring condition in patients with HIV infection. The purpose of this study was to report on the clinical aspects of eight HIV-positive patients with facial molluscum contagiosum. Also we describe the histopathologic and electron microscopic findings and discuss the treatment modalities for this unusual disease.

Inadequate epidermal homing leads to tissue damage in human cutaneous leishmaniasis

Leishmaniasis is a model disease for the study of immunoregulatory mechanisms associated with host resistance and susceptibility. In this article, Felix Tapia and colleagues propose that defects in the signaling properties of the epidermis can result in the generation of either a chronic granulomatous response, which is unable to eliminate the parasite, or a proinflammatory mucocutaneous response and tissue damage.

Epidermal Compromise in American Cutaneous Leishmaniasis

In American cutaneous leishmaniasis (ACL), Leishmania parasites enter the epidermis of the host via the bite of infected sandflies. Immune responses against the parasite vary from "effective" in localized (LCL) to a state of "selective anergy" in diffuse (DCL) cutaneous leishmaniasis, whereas the intermediate muco-cutaneous form (MCL) is characterized by an exacerbated cell-mediated immunity. We have shown that in LCL epidermis, Langerhans cells (LC) are increased, HLA-DR is universally expressed and intercellular adhesion molecule-1 (ICAM-1) immunoreactivity is distributed in patches. In addition, mRNA for IL-1 beta, IL-8, TNF alpha, TNF beta, and INF gamma may be detected in epidermal sheets by reverse transcriptase followed by polymerase chain reaction (RT-PCR). In contrast, DCL epidermis shows fewer LC than LCL epidermis, and expression of ICAM-1, HLA-DR, and IL-1 beta mRNA cannot be detected. MCL lesions show a mucosal epithelium lacking LC, but ICAM-1 is universally expressed. The clinical manifestations of ACL can be reproduced experimentally in different strains of inbred mice. In healthy mice, we have shown a positive correlation between LC and dendritic epidermal T cells (DETC) numbers. This correlation was not, however, observed in L. mexicana-infected mice, suggesting that infection alters the balance between the two cell types. In addition, agents that modulate LC and DETC cell densities change the development of experimental leishmaniasis. These results suggest that the epidermis is essential in determining the type of immune response that is developed against the Leishmania parasites.

A placebo controlled observer blind immunocytochemical and histologic study of epithelium adjacent to anogenital warts in patients treated with systemic interferon alpha in combination with cryotherapy or cryotherapy alone

OBJECTIVE

To examine biopsy specimens of tissue immediately adjacent to anogenital (AG) warts which had been treated with either cryotherapy plus subcutaneous interferon (IFN) alpha 2a or cryotherapy alone, for histological features of (a) human papilloma virus (HPV) infection (b) localised cellular immune responses, to further characterise any cellular immune infiltrates with tissue immunocytochemistry, and to relate any histological, immunocytochemical findings to the treatment response of nearby AG warts.

DESIGN

A randomised placebo controlled observer blind study.

SETTING

Genitourinary Medicine clinic, Department of Immunopathology, Royal Victoria Hospital, Belfast, N. Ireland.

SUBJECTS

Thirty patients with AG warts; 16 treated with IFN alpha 2a plus cryotherapy, and 14 treated with cryotherapy alone.

OUTCOME MEASURES

(1) Light microscopic features associated with HPV infection and local cellular immune responses. (2) Indirect immunofluorescence detection of the following cell surface markers: HLA DR, alpha one antitrypsin, CD1, CD3, CD4, CD8, CD22. (3) Clinical response of AG warts to treatment.

RESULTS

In pre-treatment biopsies only non specific indicators of HPV infection (acanthosis, 29/30 biopsies, and hyperkeratosis, 7/30 biopsies) were seen on light microscopy. Mononuclear cells were seen both throughout the upper dermis and centred around dermal blood vessels in 19/30 (63.3%) biopsies, and infiltrating into the epidermis in 12/30 (40%) biopsies. On indirect immunofluorescence CD3, CD8, CD4 antigen was detected on the surface of cells throughout the upper dermis in 24/29 (82.7%), 15/29 (51.7%), and 3/29 (10.3%), of biopsy specimens respectively. CD3 antigen, CD8 antigen and CD4 antigen was detected on the surface of cells infiltrating into the epidermis in 18/29 (62%), 7/29 (24.1%), and 6/29 (20.7%) of biopsy specimens respectively. CD1 antigen was seen on the surface of dendritic cells throughout the epidermis in all specimens; CD1 positive cells infiltrated into the upper dermis in 5/29 (17.2%). HLA DR was detected on the surface of dendritic cells throughout the epidermis in 22/29 (75.9%) of specimens, and on the surface of cells scattered both diffusely throughout the upper dermis and centred around dermal blood vessels in all specimens. Alpha one antitrypsin (A1AT) antigen was seen on the surface of cells in the upper dermis in 6/29 (20.7%) of biopsy specimens; no cells expressing CD22 surface antigen were seen. The nature of this local cellular immune response was not altered by treatment of nearby warts with either cryotherapy alone or cryotherapy plus systemic IFN alpha 2a, or related to the therapeutic outcome of these warts.

CONCLUSIONS

(1) No convincing histological evidence of HPV infection was seen in epithelium surrounding AG warts. (2) A predominantly T cell-mediated immune response (the target of which is uncertain) was seen in this perilesional epithelium. (3) In the dosage regimens used in this study, treatment of AG warts with either systemic IFN alpha 2a plus cryotherapy or cryotherapy alone did not appear to augment localised cellular immune responses (against any presumed subclinical HPV infection) in epithelium surrounding AG warts.

Immunocytochemical characterization of immune cells in lesions of American cutaneous leishmaniasis using novel T cell markers

Some recently defined lymphocyte immunophenotypes were determined in lesions of patients with American cutaneous leishmaniasis (ACL). New monoclonal antibodies have allowed the demonstration of cell surface antigens of T lymphocytes, such as CD45RA and CD45RO, which recognize different maturational stages of the same T CD4+ cell subgroup: 'virgin' (CD4+CD45RA+) and 'memory' (CD4+CD45RO+) T cells respectively. The CD4/CD8 cell ratios were higher in mucocutaneous leishmaniasis (MCL) than in localized cutaneous leishmaniasis (LCL) lesions. Diffuse cutaneous leishmaniasis (DCL) has the highest values of 'virgin' T cells; LCL and MCL patients have lower values, similar to each other. 'Memory' T cells were higher in MCL than in LCL or DCL. The ratio of 'memory'/'virgin' T cells was 7.9 for LCL, 9.6 for MCL and 2.5 for DCL. The highest value for IL-2 receptor positive cells (CD25) was observed in LCL, whereas single CD45RO-immunoreactive cells showed a peak value in DCL patients. HLA-DR+ cells were present in all three clinical forms of ACL. MCL patients showed a lack of epithelial Langerhans cell (CD1a+) in the nasal mucosa.

Morphology and membrane antigens of nonlymphoid accessory cells in oral hairy leukoplakia

We have investigated the features and distribution of accessory cells (ACs) and the relationship of these cells to each other and to lymphocytes in the epithelium and lamina propria of oral hairy leukoplakia (HL), with the objective of better defining the differentiation and mutual interactions of immune-response cells within HL as a preliminary step to understanding the onset and significance of this lesion during human immunodeficiency virus (HIV) infection. Twenty-four HIV-infected patients with HL, two asymptomatic HIV-positive subjects, and three HIV-negative subjects were studied by immunohistochemistry; five HIV-positive patients with HL and three asymptomatic HIV-positive subjects were studied by electron microscopy. In both the epithelium and the lamina propria of HL, we found cells with the immunohistochemical and ultrastructural features of variably differentiated ACs; differences were found between the epithelium and lamina propria. In the lamina propria, ACs were characterized by dendritic shape, multiple contacts with lymphocytes, expression of CD1a antigen, and ultrastructural features of fully differentiated ACs. Conversely, in the epithelium ACs showed bluntly dendritic shape, low expression of CD1a, absent expression of HLA-DR, constant expression of CD11c and CD14 antigens, only occasional contacts with lymphocytes, and ultrastructural features of variably, but always incompletely, differentiated cells of monocyte-dendritic lineage. Seventy-nanometer wide intracisternal particles, closely resembling A particles described in retroviral infections, were found in the intraepithelial ACs in two patients with HL. The defective differentiation of ACs in the epithelium of HL--possibly influenced by the perturbation of the epithelial microenvironment induced by Epstein-Barr virus, and following the direct HIV infection of these cells--and the exceptional finding of close contacts with lymphocytes suggest that the lesional epithelium of HL may constitute a pathway for the entry of foreign antigens which circumvent monitoring by ACs and can induce immune tolerance. The impairment of the local immune response in HL may contribute to the development of full blown, systemic immunodeficiency.

Acquired immunodeficiency syndrome and Epstein-Barr virus

Epstein-Barr virus is an important aetiological factor in certain HIV-related syndromes, with its opportunist expression related to the level of host immunodeficiency. In asymptomatic people co-infected with HIV, EBV activity is reflected by increased viral shedding and rises in anti-EBV titres; as immunodeficiency ensues EBV manifests as epithelial hyperproliferation in OHL, and later as B-cell lymphoma in AIDS. The suggested role of EBV as a co-factor in the progression of HIV infection and development of AIDS has not been established, although another herpesvirus, cytomegalovirus, might play such a role. Advances in our understanding of HIV regulation and its interaction with other latent (herpes) viruses should provide important molecular and pharmacological approaches to the clinical management of advanced HIV disease.

An immunohistological study of condylomata acuminata

Using an indirect immunoperoxidase method and a panel of monoclonal antibodies, anogenital warts removed from 86 individuals (28 heterosexual men, 47 homosexual men and 11 women) were studied. A constant feature was the presence of a stromal infiltrate of lymphocytes, in which CD4+ and CD8+ cells appeared in a ratio of about 5:1. Cells expressing interleukin-2 receptors were found in the stroma, amounting to 10% of the CD3+ cells. Leu 6+ epidermal dendritic cells (Langerhans' cells) were present in each wart; their density and morphology were similar to that in adjacent, apparently normal, skin. The mean number of Langerhans' cells that expressed HLA-DQ was lower than that of HLA-DR + cells. In 40 warts, HLA-DR was expressed on the surface of keratinocytes. Leu 7+ and Leu 11b+ cells were found in the epidermis of 17 and five warts, respectively. B-cells were noted in only five warts. These results are discussed in relation to persistence of wart virus infection.

Human papilloma virus in erosive oral lichen planus

Several types of human papilloma viruses (HPV) have been associated with benign and malignant squamous cell tumours of mucosal epithelium. To identify HPV in erosive oral lichen planus (OLPe), considered as a premalignant lesion, tissues from 20 patients were examined by Southern blot hybridization with 32P-labeled HPV DNA probes. Type 11 was found in 6 of the lesions while HPV types 6, 16 and 18 were not detected in any of the tissues examined. Using a type-specific polymerase chain reaction (PCR) assay for HPV-6, 11, 16 and 18, HPV-11 was detected in 8 of the samples (all of those positive by Southern blot), and, in addition, HPV-6 was found in 5 samples and HPV-16 in 3 samples. Overall, by the more sensitive PCR assay, 65% of samples were positive for HPV DNA. The finding of HPV DNA in many of the samples using two different techniques indicates a high prevalence of HPV in the OLPe afflicted oral mucosa. However, the role of HPV in the pathogenesis of OLPe has yet to be determined.

An immunohistological study of spontaneous regression of condylomata acuminata

An immunohistological study of four men whose perianal warts were undergoing spontaneous regression was undertaken, and the results compared with those obtained from non-regressing condylomata from six men. CD4+ and CD8+ cells were noted in the stroma of each wart, but there was no clear difference in the density of the infiltrate between regressing and non-regressing warts. Natural killer cells (CD16+ and CD57+) were only noted in the stroma and epidermis of regressing warts. Possible immunological mechanisms of regression of condylomata acuminata are discussed.

Immunological study of condylomata acuminata in men infected with the human immunodeficiency virus

As condylomata acuminata often persist in individuals infected with the human immunodeficiency virus (HIV), an immunohistological study of warts from infected men was undertaken to further knowledge about human papillomavirus persistence in this group. Using an indirect immunoperoxidase method and a panel of monoclonal antibodies, the phenotypes of cells were studied in cryostat sections of perianal or anal warts removed from 14 HIV-infected men (10 homosexual and 4 heterosexual) and from 16 non-infected men (10 homosexual and 6 heterosexual). Although the median numbers of CD1+, CD3+ and CD4+ cells per unit area were similar in each group of individuals, the number of CD8+ cells was significantly higher in HIV-infected homosexual men when compared with non-infected individuals and HIV-infected heterosexual men. The median CD4+ cell count in the peripheral blood was significantly higher in HIV-infected heterosexual men than in HIV-infected homosexual men (P less than 0.05). These findings may reflect differences in duration of HIV infection between the two groups. There was no significant difference in the proportion of cells expressing interleukin-2 receptors between HIV-infected and non-infected individuals. Natural killer (CD16+) cells were not identified in any of the condylomata.