Localization of Epstein-Barr virus DNA in the epithelial cells of oral hairy leukoplakia by in situ hybridization of tissue sections

Hairy leukoplakia; lessons learned: 30-plus years

Well into the fourth decade of the HIV/AIDS pandemic, we can look back on the early years, the initial discoveries, and the broad sweep of the progress of our understanding of the nature, causes, and significance of the oral lesions seen in those infected with the virus. Prominent among these is oral hairy leukoplakia (HL), a previously unknown lesion of the mouth associated with Epstein-Barr virus (EBV) and initially seen only in people with AIDS, in the then-recognized risk groups, or those shown to be HIV positive. Subsequently, it became clear that the distribution of HL extends well beyond the HIV spectrum. In this brief review, we consider the clinical and histological features of HL, discuss how it was discovered, explore its cause, diagnosis, relationship with AIDS, pathogenesis, significance in EBV biology, options for management, and how it changes with HIV/AIDS therapy.

Differentiation-Dependent LMP1 Expression Is Required for Efficient Lytic Epstein-Barr Virus Reactivation in Epithelial Cells

Epstein-Barr virus (EBV)-associated diseases of epithelial cells, including tumors that have latent infection, such as nasopharyngeal carcinoma (NPC), and oral hairy leukoplakia (OHL) lesions that have lytic infection, frequently express the viral latent membrane protein 1 (LMP1). In lytically infected cells, LMP1 expression is activated by the BRLF1 (R) immediate early (IE) protein. However, the mechanisms by which LMP1 expression is normally regulated in epithelial cells remain poorly understood, and its potential roles in regulating lytic reactivation in epithelial cells are as yet unexplored. We previously showed that the differentiation-dependent cellular transcription factors KLF4 and BLIMP1 induce lytic EBV reactivation in epithelial cells by synergistically activating the two EBV immediate early promoters (Zp and Rp). Here we show that epithelial cell differentiation also induces LMP1 expression. We demonstrate that KLF4 and BLIMP1 cooperatively induce the expression of LMP1, even in the absence of the EBV IE proteins BZLF1 (Z) and R, via activation of the two LMP1 promoters. Furthermore, we found that differentiation of NOKs-Akata cells by either methylcellulose suspension or organotypic culture induces LMP1 expression prior to Z and R expression. We show that LMP1 enhances the lytic infection-inducing effects of epithelial cell differentiation, as well as 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate treatment, in EBV-infected epithelial cells by increasing expression of the Z and R proteins. Our results suggest that differentiation of epithelial cells activates a feed-forward loop in which KLF4 and BLIMP1 first activate LMP1 expression and then cooperate with LMP1 to activate Z and R expression.IMPORTANCE The EBV protein LMP1 is expressed in EBV-associated epithelial cell diseases, regardless of whether these diseases are due to lytic infection (such as oral hairy leukoplakia) or latent infection (such as nasopharyngeal carcinoma). However, surprisingly little is known about how LMP1 expression is regulated in epithelial cells, and there are conflicting reports about whether it plays any role in regulating viral lytic reactivation. In this study, we show that epithelial cell differentiation induces LMP1 expression by increasing expression of two cellular transcription factors (KLF4 and BLIMP1) which cooperatively activate the two LMP1 promoters. We also demonstrate that LMP1 promotes efficient lytic reactivation in EBV-infected epithelial cells by enhancing expression of the Z and R proteins. Thus, in EBV-infected epithelial cells, LMP1 expression is promoted by differentiation and positively regulates lytic viral reactivation.

Oral hairy leukoplakia in patients without HIV: presentation of 2 new cases

OBJECTIVE

We report 2 cases of oral hairy leukoplakia (OHL) in patients without HIV and present a comprehensive review of OHL in HIV-negative individuals.

STUDY DESIGN

Two cases of non-HIV-associated OHL are described. A PubMed search identified previously reported cases. The attributes of those cases were ascertained.

RESULTS

OHL was confirmed in both of our cases. Both patients used inhaled steroids for pulmonary disorders, and were found to have depressed levels of immunoglobulin M. Additionally, 76 cases were identified in the literature. The condition occurred in association with various medical conditions, with the majority of patients on immunosuppressant medications (67 of 76). Systemic drugs were implicated most frequently. The condition has also been reported in healthy individuals (6 of 76).

CONCLUSIONS

Although thought of as an HIV/AIDS-associated condition, OHL can develop in patients without HIV, including healthy individuals. There is a strong correlation between the use of immunosuppressants and development of OHL in these patients.

Oro-facial manifestations in paediatric HIV: a comparative study of institutionalized and hospital outpatients

The aim of the study was to compare dental caries status and the number and type of oral mucosal lesions in HIV positive children from a hospital outpatient department and an institutionalized setting. Oral examinations were performed using presumptive diagnostic criteria. The Fisher's Exact and the Mann-Whitney tests were used for statistical comparison of the two study groups. A total of 169 children were examined of whom 42% were institutionalized and 58% hospital outpatients. One institutionalized child presented with Noma. Twenty-one percent of the institutionalized population presented with molluscum contagiosum, while none of the hospital outpatients presented with this condition. Significantly more intraoral mucosal lesions were observed in the hospital compared with the institutionalized group. The most frequently encountered oral lesion was candidiasis. Pseudomembranous candidiasis was the most common type. Twice as many intraoral ulcers were recorded in the institutionalized group. Thirty-nine percent of the hospitalized patients had multiple lesions compared with 28% in the institutionalized group. Almost three quarters of both populations were caries-free. The mean DMFT was considerably higher in the hospital population. For both the permanent and primary teeth, the decayed component (D/d) made up the major part of the DMFT/dmft, followed by the missing (M/m) component. No fillings were recorded in either the primary or permanent teeth for both groups. Oral lesions are common in HIV populations and were seen in both the hospital and institutionalized groups, at high prevalence levels (63 and 45%). HIV infected children should be considered high risk for caries because of the use of chronic medications, and to receive appropriate care in terms of both treatment and services.

Occurrence and Management of Opportunistic Infections Associated with HIV/AIDS in Asia

Illnesses, diseases and malignancies occur among HIV-infected individuals along a continuum. These are directly correlated with the degree of immune suppression and are caused by common patho gens and opportunistic infections. In decreasing order offrequency, frequent opportunistic infections and malignancies that occur in Asia are: Mycobacterium tuberculosis, Cryptococcus neoformans, Candida spp., Herpes simplex, Cryptosporidium parvum, Pneumocystis carinii, Toxoplasma gondii, non-Hodgkin's lymphoma and Kaposi's sarcoma. The association of morbidityand mortality due to co-infection with HIV and M.tuberculosis has become more evident in the region. Natural history studies conducted in Mumbai and Bangkok have reported incubation periods from infection to AIDS of eight and nine years respectively. Despite the advent of antiretroviral therapy (ART) and improved affordability of the generic drugs, only 30,000 (2 to 3 per cent) of the estimated 1.3 million eligible persons with AIDS in South Asia are presently on AR T. Apparently, the focus of the low-cost care in the region still continues to be of care and management of prevalent opportunistic infections. As care practices start to include ART over the next few years, there will be consequent change in the occurrence of opportunistic infections and need for their prophylaxis.

CCAAT/enhancer binding protein alpha interacts with ZTA and mediates ZTA-induced p21(CIP-1) accumulation and G(1) cell cycle arrest during the Epstein-Barr virus lytic cycle

Cellular CCAAT/enhancer binding protein alpha (C/EBPalpha) promotes cellular differentiation and has antimitotic activities involving cell cycle arrest at G(1)/S through stabilization of p21(CIP-1)/WAF1 and through transcriptional activation of the p21 promoter. The Epstein-Barr virus lytic-cycle transactivator protein ZTA is known to arrest the host cell cycle at G(1)/S via a p53-independent p21 pathway, but the detailed molecular mechanisms involved have not been defined. To further evaluate the role of ZTA in cell cycle arrest, we constructed a recombinant adenovirus vector expressing ZTA (Ad-ZTA), whose level of expression at a low multiplicity of infection in normal human diploid fibroblast (HF) cells was lower than or equal to the physiological level seen in Akata cells lytically induced by EBV (EBV-Akata cells). Fluorescence-activated cell sorting analysis of HF cells infected with Ad-ZTA confirmed that G(1)/S cell cycle arrest occurred in the majority of ZTA-positive cells, but not with an adenovirus vector expressing green fluorescent protein. Double-label immunofluorescence assays (IFA) performed with Ad-ZTA-infected HF cells revealed that only ZTA-positive cells induced the expression of both endogenous C/EBPalpha and p21 and blocked the progression into S phase, as detected by a lack of incorporation of bromodeoxyuridine. The stimulation of endogenous ZTA protein expression either through treatment with tetradecanoyl phorbol acetate in D98/HR1 cells or through B-cell receptor cross-linking with anti-immunoglobulin G antibody in EBV-Akata cells also coincided with the induction of both C/EBPalpha and p21 and their mRNAs, as assayed by Northern blot, Western blot, and IFA experiments. Mechanistically, the ZTA protein proved to directly interact with C/EBPalpha by coimmunoprecipitation in EBV-Akata cells and with DNA-bound C/EBPalpha in electrophoretic mobility shift assay experiments, and the in vitro interaction domain encompassed the basic leucine zipper domain of ZTA. ZTA also specifically protected C/EBPalpha from degradation in a protein stability assay with a non-EBV-induced Akata cell proteasome extract. Furthermore, both C/EBPalpha and ZTA were found to specifically associate with the C/EBPalpha promoter in chromatin immunoprecipitation assays, but the interaction with ZTA appeared to be mediated by C/EBPalpha because it was abolished by clearing with anti-C/EBPalpha antibody. ZTA did not bind to or activate the C/EBPalpha promoter directly but cooperatively enhanced the positive autoregulation of the C/EBPalpha promoter by cotransfected C/EBPalpha in transient luciferase reporter gene assays with Vero and HeLa cells as well as with DG75 B lymphocytes. Similarly, ZTA alone had little effect on the p21 promoter in transient reporter gene assays, but in the presence of cotransfected C/EBPalpha, ZTA enhanced the level of C/EBPalpha activation. This effect proved to require a previously unrecognized region in the proximal p21 promoter that contains three high-affinity C/EBPalpha binding sites. Finally, in C/EBPalpha-deficient mouse embryonic fibroblasts (MEF), Ad-ZTA was unable to induce either p21 or G(1) arrest, whereas it was able to induce both in wild-type MEF. Overall, we conclude that C/EBPalpha is essential for at least one pathway of ZTA-induced G(1) arrest during EBV lytic-cycle DNA replication and that this process involves a physical piggyback interaction between ZTA and C/EBPalpha leading to greatly enhanced C/EBPalpha and p21 levels through both transcriptional and posttranslational mechanisms.

Advanced diagnostic methods in oral and maxillofacial pathology. Part I: molecular methods

The practice of pathology is currently undergoing significant change, in large part due to advances in the analysis of DNA, RNA, and proteins in tissues. These advances have permitted improved biologic insights into many developmental, inflammatory, metabolic, infectious, and neoplastic diseases. Moreover, molecular analysis has also led to improvements in accuracy of disease diagnosis and classification. It is likely that, in the future, these methods will increasingly enter into the day-to-day diagnosis and management of patients. The pathologist will continue to play a fundamental role in diagnosis and will likely be in a pivotal position to guide the implementation and interpretation of these tests as they move from the research laboratory into diagnostic pathology. The purpose of this 2-part series is to provide an overview of the principles and applications of current molecular biologic and immunologic tests. Part I will discuss the biologic fundamentals of DNA, RNA, and proteins and the methods that are currently available or likely to become available to the pathologist in the next several years for their isolation and analysis in tissue biopsies.

Detection of lymphocytes productively infected with Epstein-Barr virus in non-neoplastic tonsils

Epstein-Barr virus (EBV) persists for life in the infected host. Little is known about EBV reactivation and regulation of virus persistence in healthy individuals. We examined tonsils of chronic tonsillitis patients to detect EBV transcripts, EBV genomes and lytic proteins. LMP1 transcripts were observed in 11 of 15 specimens and BZLF1 transcripts were detected in six. Multiple copies of EBV genome equivalents per cell, and ZEBRA- and viral capsid antigen-positive cells were also detected in tonsillar lymphocytes. These results indicate that EBV productively infected cells may survive in the face of immune surveillance in the tonsils. Thus, EBV replication may occur in tonsillar lymphocytes, and tonsillar lymphoid tissues may play a role in the maintenance of EBV load in vivo.

Oral infections and other manifestations of HIV disease

Oral lesions are important in the clinical spectrum of HIV/AIDS, arousing suspicion of acute seroconversion illness (aphthous ulceration and candidiasis), suggesting HIV infection in the undiagnosed individual (candidiasis, hairy leukoplakia, Kaposi's sarcoma, necrotizing ulcerative gingivitis), indicating clinical disease progression and predicting development of AIDS (candidiasis, hairy leukoplakia), and marking immune suppression in HIV-infected individuals (candidiasis, hairy leukoplakia, necrotizing periodontal disease, Kaposi's sarcoma, long-standing herpes infection, major aphthous ulcers). In addition, oral lesions are included in staging systems for HIV disease progression and as entry criteria or endpoints in clinical trials of antiretroviral drugs. Recognition and management of these oral conditions is important for the health and quality of life of the individual with HIV/AIDS. In keeping with this, the U.S. Department of Health Services Clinical Practice Guideline for Evaluation and Management of Early HIV Infection includes recommendations that an oral examination, emphasizing oral mucosal surfaces, be conducted by the primary care provider at each visit, a dental examination by a dentist should be done at least two times a year, and patients should be informed of the importance of oral care and educated about common HIV-related oral lesions and associated symptoms.

Four consecutive arginine residues at positions 836-839 of EBV gp110 determine intracellular localization of gp110

Epstein-Barr virus (EBV) glycoprotein 110 (gp110) has sequence homology with herpes simplex virus-1 (HSV-1) gB; however the role of gp110 in EBVs' life cycle differs from that of gB. Unlike HSV-1 gB, which is essential for HSV-1 infection but dispensable for virus production, gp110 is required for assembly and egress of EBV. EBV gp110 is found mainly in the endoplasmic reticulum (ER)/nuclear membrane, whereas little or no gp110 is detected in the plasma membrane or a mature viral particle. Conversely, HSV-1 gB is abundant in the envelope of mature virions and in the plasma membrane as well as in the ER/nuclear membrane of HSV-1-infected cells. Interestingly, there are four consecutive arginine residues (at positions 836-839 of gp110) in the C-terminal domain previously shown to be important for gp110's intracellular localization. To determine whether these arginines function as an ER/nuclear localization signal, point mutants were constructed differentially substituting the four arginines. The glycosylation pattern and intracellular localization of the mutants were investigated by assessing sensitivity to endoglycosidase H (endo H) digestion and performing indirect immunofluorescence assays. Substitution of part of the four arginines changed the glycosylation profile and targeting of gp110. In addition, mutations preserving the net charge of the four arginines as well as those causing net charge shift resulted in the changed intracellular localization and altered glycosylation pattern. These results suggest that not only the net charge but also the conformation of the four arginines are important for gp110's processing and subcellular localization.

Update on the cutaneous manifestations of HIV infection. Clinical and pathologic features

Skin is the most commonly affected organ in patients with HIV. As such, cutaneous manifestations of HIV infection have been the subject of intense scrutiny as well as the topic of many articles. A broad range of infectious and noninfectious skin lesions may develop during the course of the disease. This article discusses the clinical and pathological cutaneous manifestations of HIV infection.

Detection of Epstein-Barr virus (EBV) DNA and antigens in oral mucosa of renal transplant patients without clinical evidence of oral hairy leukoplakia (OHL)

The use of the polymerase chain reaction (PCR) to detect the presence of Epstein-Barr virus (EBV) DNA in oral mucosa in the absence of specific lesions gives rise to the problem of identifying the real viral replication sites. To verify whether the detection of EBV is due to salivary contamination or its true replicative capacity in oral mucosa, saliva samples and exfoliated cells from four different oral mucosa sites were taken from 40 renal transplant patients and 20 normal subjects for examination by PCR using two pairs of primers specific for the BamHI-L and BamHI-K genomic regions. EBV-specific sequences were detected in one or more of the oral mucosa samples from 29 transplant patients (72.5%) and six healthy controls (30%), and in the saliva samples of 16 transplant patients (40%) and three healthy controls (15%). A total of 89 oral mucosa smears from 29 transplant patients, and 13 from healthy subjects, were EBV-positive. The positive samples were also investigated by means of in situ hybridization in order to confirm the intracellular presence of the viral genome, and by means of immunofluorescence testing with monoclonal antibodies to assess the possible expression of viral antigens. Hybridization with the EBV-specific probe was observed in 40/ 89 and 2/13 samples, respectively. Latent antigens (with or without lytic antigens) were detected in only 23 of the 40 samples (collected from eight different transplant patients) that were positive by in situ hybridization. Our data show that EBV is more frequently present in the oral mucosa of immunodeficient patients (where it can efficiently replicate) than in normal subjects.

Update on cutaneous manifestations of HIV infection

The skin is affected in virtually all patients with HIV infection. Many articles and several books have been published that deal with these disorders for a number of reasons. First, cutaneous disease may serve as the initial or only problem that the patient suffers for much of the course of the HIV infection. Second, serious opportunistic infections may present for the first time in the skin, so that a skin lesion may be a harbinger of the patient's having a life-threatening illness. Third, skin disorders in these patients may appear unusual and hence may not be accurately diagnosed by clinical inspection alone. Furthermore, response to treatment may be poorer than expected. Thus, skin diseases in the HIV-infected patient are important and, in some cases, may be the most debilitating element of the patient's condition.

Comparison of cytopathic changes in oral hairy leukoplakia with in situ hybridization for EBV DNA

OBJECTIVE

It has been observed that the cytopathic changes in hairy leukoplakia (HL) correlate with ultrastructural evidence of intra-keratinocyte herpes-type viral particles. In situ hybridization is considered to be the definitive confirmation of Epstein-Barr virus (EBV)-induced HL. This study evaluated the consistency of histopathological findings, which many believe to be diagnostic, with in situ hybridization for EBV-DNA in 60 patients with lesions clinically suggestive of HL.

MATERIALS AND METHODS

Hematoxylin and eosin (H&E)-stained sections were reviewed independently by three oral pathologists who did not know the hybridization results. The presence in keratinocytes of nuclear inclusions and/or homogenization, believed to be specific for EBV in these lesions, was used as an indicator for infection. Cytoplasmic changes were evaluated separately.

RESULTS

With in situ hybridization, 48 cases were positive and 12 were negative. When the two methods were compared, pathologist concurrence ranged from 83% to 92%. False negatives ranged from 6% to 19%, and false positives ranged from 8% to 25%. Cytoplasmic ballooning, homogenization, and perinuclear clearing were evident in all cases of hybridization-confirmed HL; however, these changes were also noted in 75% (9/12) of the cases with negative hybridization results. Most confirmed HL cases exhibited both nuclear homogenization and inclusions, although the former was more consistently seen.

CONCLUSION

Cytoplasmic changes did not agree well with EBV-DNA hybridization results, whereas nuclear changes demonstrated good, but not complete, agreement. In appropriate clinical settings, the finding of nuclear inclusions and/or homogenization may be of diagnostic value. However, because the potential for false positives and negatives is high, H&E cytopathology should not be used as a substitute for in situ hybridization in the definitive diagnosis of oral hairy leukoplakia.

Apoptosis-associated proteins in oral hairy leukoplakia

OBJECTIVE

To test the hypothesis that the anti-apoptotic ability of Epstein-Barr virus (EBV) may result in altered expression of apoptosis-associated proteins in oral hairy leukoplakia (HL), we evaluated HL tissue and normal epithelium for these proteins by immunohistochemistry.

MATERIALS AND METHODS

Twenty formalin-fixed, paraffin-embedded specimens of HL lesions and six specimens of normal control mucosa were selected from archived tissue specimens. Bcl-2, Bcl-x, Bax and p53 apoptosis-associated proteins were evaluated in immunohistochemically stained tissue sections according to staining intensity and pattern. The percentage of p53-positive basal cells was estimated in sequential fields.

RESULTS

Generally, there were only slight differences in the expression of Bcl-2 and Bcl-x proteins in the epithelium of HL and control tissue. The staining for Bcl-2 was weaker in keratinocytes than in putative melanocytes and Langerhans cells. Equivocal diffuse cytoplasmic staining of prickle cells was also noted. Keratinocytes throughout the epithelium stained positively for Bcl-x protein, although upper layers were more weakly stained. The 'balloon' keratinocytes in HL were infrequently positive for Bcl-x. Bax staining in HL differed from that in control tissue in being more heterogeneous. The staining reaction in HL was weak to negative in upper epithelial levels where 'balloon' keratinocytes were located. Weak to moderate nuclear p53 protein staining was detected in a mean of 25.3% of basal keratinocytes in all but one of the HL specimens; weak staining was seen in only two control specimens.

CONCLUSIONS

We found only slight immunohistochemical evidence that expression of the apoptosis-associated proteins is altered in HL. p53 appears to over-expressed in HL; we speculate that this may be related to up-regulation or stabilization of wild-type p53 protein related to EBV infection.

Mass in the post nasal space and acquired immune deficiency syndrome

We report a case of previously undiagnosed acquired immunodeficiency syndrome (AIDS) who had a mass in the post-nasal space causing almost complete nasal obstruction. Histology showed both respiratory and squamous epithelium covering an active chronic inflammatory infiltrate. Lymphoma, Kaposi's sarcoma and infiltrative fungal sinusitis were excluded. There was no evidence of the common viruses associated with lesions in AIDS. Unlike adenoid hypertrophy, the lesion was an exuberant growth with an additional chronic inflammatory reaction due to ulceration of the surface epithelium.

A rapid microwave-in situ hybridization method for the definitive diagnosis of oral hairy leukoplakia: comparison with immunohistochemistry

As a diagnostic technique, in situ hybridization requires a long processing time, a degree of expertise and may be difficult to handle routinely in some laboratories. To simplify the in situ hybridization method, we have modified a microwave in situ hybridization technique and applied it to oral hairy leukoplakia (OHL) biopsies obtained from 10 HIV-seropositive patients (definitively diagnosed by a conventional in situ hybridization technique) with appropriate controls. It was necessary to design a novel chamber to avoid drying of sections during the hybridization step. This modified microwave in situ hybridization technique was equispecific and equisensitive to the conventional technique and it shortens the hybridization time from overnight incubation to 14 minutes. To determine the sensitivity of our microwave in situ hybridization method we applied it to previously documented tongue tissue obtained from an AIDS autopsy without clinical evidence of OHL, but found to contain Epstein-Barr virus (EBV) by conventional in situ hybridization. This tissue specimen acted as a low EBV copy number, positive control. The sensitivity of immunohistochemistry using three different commercial detection kits was compared to that of in situ hybridization on the same tissues, following optimisation steps. This included the use of 2 cycles of primary and biotinylated secondary antibodies (antibody double cycling). Clearly positive signals for EBV were detected in all OHL biopsies with the Vectastain Elite ABC and the Histostain-SP kits. The sensitivity of the three commercial detection kits was evaluated at immunohistochemistry level by their application to the low-EBV copy number positive control specimen. Signals for EBV antigen in the low copy number positive control specimen were obtained only with the Vectastain Elite ABC kit. This indicates that, in this application, use of the Vectastain Elite ABC kit gives comparable sensitivity for immunohistochemistry to that found by in situ hybridiation.

Epstein-Barr virus (EBV) infection and undifferentiated carcinoma of the parotid gland in Caucasian patients

The Epstein-Barr virus (EBV) has been detected in certain types of lymphoma and some epithelial neoplasms such as nasopharyngeal lymphoepithelioma and occasional undifferentiated carcinomas in several organs including the salivary glands. However, clonal EBV genomes have been detected in undifferentiated carcinomas of the parotid gland exclusively in Alaskan natives and Eskimos, both groups being at the highest risk for nasopharyngeal carcinoma. The authors investigated the possibility that EBV may be present in undifferentiated parotid carcinomas in Caucasian subjects. To test this hypothesis, in situ hybridization (ISH) technique with biotinylated EBV-DNA probes was utilized on routinely processed, paraffin-embedded tissues from 7 cases of undifferentiated carcinomas of the parotid gland. EBV genomes were demonstrated in the cytoplasm of tumor cells from 3 out of 7 specimens tested. Surprisingly, EBV genomes were found in 3 out of 5 (60%) undifferentiated carcinomas that had developed in patients with a history of a long-persisting asymptomatic parotid mass, which had suddenly increased in size. Conversely, none of the undifferentiated carcinomas with continuous and rapid growth studied was found to be positive for EBV-DNA by ISH technique. Taken together, these data might suggest a possible role of EBV in the transformation of benign parotid gland lesions into malignant and aggressive undifferentiated carcinoma of the parotid gland, the so-called carcinoma expleomorphic adenoma.

In situ hybridization and the polymerase chain reaction (PCR) in the analysis of biopsies and exfoliative cytology specimens for definitive diagnosis of oral hairy leukoplakia (OHL)

The definitive diagnosis of oral hairy leukoplakia (OHL) demands that Epstein-Barr virus (EBV) is demonstrated in the lesional tissue, since the histopathological features on conventional light microscopy are not pathognomonic. We have investigated the possible use of polymerase chain reaction (PCR) technology in reaching a definitive diagnosis of this lesion by its application to ten biopsy specimens with definitive diagnoses of OHL determined by in situ hybridization. EBV DNA was demonstrated by PCR in all ten OHL biopsy specimens analysed, and none of ten control specimens. Furthermore, we have investigated the role of PCR in analysis of exfoliative cytology samples collected from the lateral border of the tongue by a minimally-invasive scraping technique. EBV DNA was not only detected in all OHL lesional scrapings but also in more than one-third of healthy controls, due to viral presence in saliva at the time of sampling. In this application, the highly sensitive PCR technique has low specificity and cannot be recommended.

Hairy leukoplakia after bone marrow transplantation

Hairy leukoplakia in 10 patients after bone marrow transplantation was identified clinically and assessed histologically. In situ hybridization for Epstein-Barr virus and human papilloma virus confirmed Epstein-Barr virus in hairy leukoplakia in two cases, and human papillomavirus in three cases. All cases with clinical follow-up resolved without treatment. These findings suggest that severe immunosuppression after a bone marrow transplantation may result in the development of hairy leukoplakia, and that as the immunosuppression resolves after the transplant the lesions also resolve.

Epstein-Barr virus latent and replicative gene expression in oral hairy leukoplakia

Oral hairy leukoplakia is an epithelial lesion of the tongue associated with productive infection by Epstein-Barr virus (EBV). However, no data concerning the pattern of EBV latent gene expression have been reported, and it remains unresolved whether true latent infection occurs in basal cell layers of oral hairy leukoplakia. We have studied six cases of oral hairy leukoplakia using monoclonal antibody immunohistology for EBV latent--EB nuclear antigen (EBNA) 1, EBNA 2 and latent membrane protein 1 (LMP 1); immediate-early (BZLF1); and replicative (EA, VCA, MA) proteins, and for the EBV-receptor (CD21 antigen). EBV DNA was demonstrated by nucleic acid in situ hybridization. Mid- to upper-zone keratinocytes contained EBV DNA and co-expressed EBNA 1, EBNA 2 (5 of 6 cases), LMP 1, BZLF1 protein, EA, VCA and MA. No EBV genome or gene expression could be demonstrated in basal or parabasal cells. Spinous keratinocytes were labelled by anti-CD21 antibodies HB5 and B2, but did not express the EBV-receptor as defined by reactivity with OKB7. The co-expression of latent and replicative infection-associated antigens is striking, indicating possible functional roles for latent proteins during the productive cycle. Our results suggest that oral hairy leukoplakia is caused by repeated direct infection of upper epithelial cells with virus from saliva or adjacent replicatively infected cells, rather than by a latent EBV infection of basal epithelial cells with a differentiation-dependent switch to productive infection as previously proposed.

Unusual oral presentation of non-Hodgkin's lymphoma in association with HIV infection

In 4.4% of human immunodeficiency virus-associated non-Hodgkin's lymphoma the presenting lesion is seen in the mouth. Often the lesion may clinically resemble a less sinister process, and a definitive diagnosis of lymphoma may be delayed. We describe three unusual cases of non-Hodgkin's lymphoma, appearing intraorally in association with other oral lesions, in HIV-positive homosexual men. The three patients reported here were all diagnosed as having diffuse, large-cell malignant non-Hodgkin's lymphoma. We performed Epstein-Barr virus DNA in-situ hybridization on our cases and Epstein-Barr virus DNA sequences were not seen. We review the pertinent literature and stress the importance of including non-Hodgkin's lymphoma in the differential diagnosis of oral lesions in patients at risk of HIV infection.

Immunocytochemical detection of herpes viruses in oral smears of HIV-infected patients

Cytologic smears (CS) were taken from the lateral border of the tongue of HIV-seropositive patients (HIV+) (n = 39) and of seronegative controls (HIV-) (n = 19) and examined by immunocytochemistry (APAAP) and in situ hybridization (ISH) (biotinylated DNA probes) for the presence of viral antigens/DNA of EBV and CMV. While none of the HIV controls showed positive results for EBV antigen, 61% (APAAP) resp. 79% (ISH) of oral epithelial cells in the group of HIV+ patients were EBV-positive. While all CS taken from areas with the clinical diagnosis of hairy leukoplakia (HL) were EBV positive (APAAP and/or ISH), the detection of EBV in CS from uninvolved oral mucosa seemed to be associated with the later development of HL. In the group of HIV+ patients the detection rate for CMV was about five times (APAAP) resp. three times (ISH) higher than in HIV- persons. This non-invasive technique seems to be a valuable tool to screen for viral antigens/genomes.

Significance of oral hairy leukoplakia

Since the original description of oral hairy leukoplakia among homosexual men in San Francisco in 1984, this white lesion of the tongue has been seen in the mouths of persons infected with the human immunodeficiency virus (HIV) worldwide. Its presence in HIV-positive persons usually but not always indicates fairly rapid progression to acquired immunodeficiency syndrome in the absence of antiretroviral therapy. Although the lesion appears to be common in HIV-positive persons, it is also, albeit rarely, seen in other conditions associated with immunosuppression. Epstein-Barr virus is associated with and presumably causes hairy leukoplakia, and the lesion offers insights into the biology of this ubiquitous DNA-oncogenic virus.

Detection of Epstein-Barr virus in lymphoid tissues of patients with infectious mononucleosis by in situ hybridization

Although the immunological response during infectious mononucleosis (IMN) has been studied in detail, little is known about the spread of Epstein-Barr virus (EBV) in lymphoid organs or the topographical distribution of the infected cells. In this study, EBV was detected in 11 lymph nodes, 4 tonsils, and 1 spleen of 16 patients with IMN. The predominant cell type positive for the EBV genome was identified as small lymphocytes localized chiefly within typical T areas, preferentially in perifollicular and interfollicular regions of the lymph node. A few endothelia of epithelioid venules were also found to be positive. Furthermore, a small number of sinus lining cells of lymph nodes exhibited labelling. Altogether, only a small number of cells, not exceeding 1 per cent of all cells, were infected with EBV. Our results show that only a small number of lymphocytes carry the EBV and that besides B lymphocytes, other cell constituents of lymphatic tissues are infected by EBV during IMN.

Relationship of eukaryotic DNA replication to committed gene expression: general theory for gene control

The historic arguments for the participation of eukaryotic DNA replication in the control of gene expression are reconsidered along with more recent evidence. An earlier view in which gene commitment was achieved with stable chromatin structures which required DNA replication to reset expression potential (D. D. Brown, Cell 37:359-365, 1984) is further considered. The participation of nonspecific stable repressor of gene activity (histones and other chromatin proteins), as previously proposed, is reexamined. The possible function of positive trans-acting factors is now further developed by considering evidence from DNA virus models. It is proposed that these positive factors act to control the initiation of replicon-specific DNA synthesis in the S phase (early or late replication timing). Stable chromatin assembles during replication into potentially active (early S) or inactive (late S) states with prevailing trans-acting factors (early) or repressing factors (late) and may asymmetrically commit daughter templates. This suggests logical schemes for programming differentiation based on replicons and trans-acting initiators. This proposal requires that DNA replication precede major changes in gene commitment. Prior evidence against a role for DNA replication during terminal differentiation is reexamined along with other results from terminal differentiation of lower eukaryotes. This leads to a proposal that DNA replication may yet underlie terminal gene commitment, but that for it to do so there must exist two distinct modes of replication control. In one mode (mitotic replication) replicon initiation is tightly linked to the cell cycle, whereas the other mode (terminal replication) initiation is not cell cycle restricted, is replicon specific, and can lead to a terminally differentiated state. Aberrant control of mitotic and terminal modes of DNA replication may underlie the transformed state. Implications of a replicon basis for chromatin structure-function and the evolution of metazoan organisms are considered.

Differentiation-associated expression of the Epstein-Barr virus BZLF1 transactivator protein in oral hairy leukoplakia

The BZLF1 protein of Epstein-Barr virus (EBV) is a key immediate-early protein which has been shown to disrupt virus latency in EBV-infected B cells. We have generated a monoclonal antibody, BZ1, to BZLF1 which reacts in immunohistology, immunoblotting, and immunoprecipitation and which recognizes both the active, dimeric form and the inactive, monomeric form of the protein. Biopsies of oral hairy leukoplakia, an AIDS-associated lesion characterized by high-level EBV replication, were examined by immunohistochemistry using the BZ1 monoclonal antibody. A differentiation-associated pattern of BZLF1 expression was observed, BZ1 reacting with nuclei of the upper spinous layer of the lesion. This finding suggests that the BZLF1 promoter may be regulated by the degree of squamous differentiation. A comparison of in situ hybridization to EBV DNA and viral capsid antigen staining with BZ1 reactivity suggested that BZLF1 expression precedes rampant virus replication. The inability to detect EBV in the lower epithelial layers of oral hairy leukoplakia raises questions concerning the nature of EBV latency and persistence in stratified squamous epithelium.

Rapid detection of Epstein-Barr virus DNA in clinical samples of oral hairy leukoplakia with HRP-labeled DNA probes and in situ hybridization

An in situ hybridization technique, using horseradish peroxidase (HRP)-labeled DNA probes containing a portion of the Epstein-Barr virus (EBV) genome, was used to detect EBV DNA in tongue sections and smears from patients with oral lesions resembling the clinical features of oral hairy leukoplakia (HL). Eleven biopsy specimens (six consistent with HL, four normal tongue controls, and one leukoplakia) and 11 tongue smears were evaluated for the presence of EBV, cytomegalovirus (CMV), herpes simplex virus (HSV), and human papillomavirus (HPV) type 16. Following hybridization, six biopsy specimens and 10 tongue smears were found positive for EBV. All biopsy cases were negative for CMV, HSV, HPV-16 and the negative control probe. The specificity of the in situ hybridization assay was 100%. These results suggest that in situ hybridization using HRP-labeled DNA probes may be useful as a rapid diagnostic method for the detection of EBV in tongue sections or smears from patients diagnosed with HL.

Altered HIV expression and EBV-induced transformation in coinfected PBLs and PBL subpopulations

Human immunodeficiency virus (HIV) IIIB expression and Epstein-Barr virus (EBV) B95.8-induced transformation were studied during coinfection. Coinfection of peripheral blood lymphocyte (PBL) cultures with HIV and EBV resulted in down-regulation of HIV expression. EBV-induced and spontaneous transformation were markedly reduced in PBL cultures exposed to HIV before EBV. On the other hand, transformation was enhanced when PBL cultures were infected with HIV either simultaneous to or after EBV. Reconstitution of EBV-infected B cell cultures with autochthonous T cells demonstrated that HIV-infected T cells had a reduced ability to inhibit EBV-induced transformation. PHA stimulation of HIV-infected T cells eliminated their ability to inhibit EBV-induced transformation. Lymphoblastoid cell lines (LCLs) established from coinfected PBLs expressed B cell markers and were EBV positive, while a large proportion of the LCLs expressed HIV antigens, released reverse transcriptase activity into the supernatant, and produced syncytia when cocultivated with indicator cell line SupT1. HIV provirus could be detected in LCLs established from coinfected cultures by PCR amplification using specific sets of amplimers for gag and env genes of HIV. To more closely examine the role of various cell types in lymphocyte transformation and HIV replication during coinfection, experiments were carried out using subpopulations enriched for either B or T cells. Simultaneous coinfection of purified B cells with EBV and HIV resulted in a marked reduction of HIV expression, whereas EBV-induced transformation was enhanced. In contrast, spontaneous B cell transformation was inhibited by HIV. A proportion of LCLs established from purified B cells coinfected with EBV and HIV expressed HIV antigens, released reverse transcriptase activity, and produced syncytia on SupT1 cells. These results demonstrate that the IIIB strain of HIV and B95.8 strain of EBV can interact during coinfection of B cells to alter the course of virus expression.

Altered patterns of keratin expression in oral hairy leukoplakia: prognostic implications

To establish why the lateral border of tongue is the site of predilection for the development of hairy leukoplakia (HL) and to understand its likely behavior, the pattern of keratin expression was compared in 8HL lesions with matched controls in an immunocytochemical study. Keratins 7, 8, 18 were absent in HL and normals; uniform basal keratin 19 was present in normals but much reduced in HL. Loss of conformationally sensitive epitopes of keratin 14 in lower epithelial layers was seen in HL. Overall expression of non-cornifying keratins 4/13 was reduced in HL and completely lost in the parakeratin zone. Expression of the high-turnover keratins 6/16 was reduced in HL. The HL keratin phenotype suggests that no dysplastic change is likely, but in contrast there is enhanced differentiation, which suggests a benign course for the condition.

Oral hairy leukoplakia in HIV infection: a diagnostic pitfall

Twenty-nine human immunodeficiency virus (HIV)-infected patients with white, nonremovable lesions on the lateral border of the tongue, clinically suggestive of oral hairy leukoplakia (HL), were studied. In particular, the value of local antifungal therapy in establishing the diagnosis of HL was investigated. In 15 patients (52%) the lesions could be ultimately attributed to a candidal infection of the tongue. In 10 of the remaining 14 patients, a biopsy was obtained from lesions persisting after local antifungal treatment. In all biopsy specimens, the diagnosis of HL was confirmed by histopathologic examination and the demonstration of Epstein-Barr virus DNA by polymerase chain reaction, Southern blot hybridization, and DNA in situ hybridization. The present data confirm that the diagnosis of HL in HIV-infected patients cannot be reliably made on clinical criteria alone, but requires histopathologic confirmation including the demonstration of Epstein-Barr virus DNA, preferably by DNA in situ hybridization. However, with regard to the differential diagnosis of white, nonremovable lesions on the lateral border of the tongue in HIV-infected patients, the present study suggests that persistence of lesions after local antifungal therapy is highly suggestive of HL.

Epstein-Barr virus receptors but not viral DNA are present in normal and malignant oral epithelium

The presence and distribution of Epstein-Barr Virus receptors (EBVR's) on a range of normal (n = 18), dysplastic (n = 10) and malignant (n = 20) oral mucosa were studied by immunocytochemical methods using the monoclonal antibodies (MAb's) HB5 and B2. EBVR's were demonstrated as membrane staining of the spinous layers of normal non- and parakeratinized epithelium, indicating that EBVR's are differentiation-linked. This distribution was retained in dysplastic epithelium. Tissue from oral squamous cell carcinomas (SCC's) showed variable reactivity of only a few cells scattered randomly within the samples. Furthermore, a sensitive in situ hybridization (ISH) technique was used to determine if Epstein-Barr virus (EBV) was present in normal (n = 15) and oral squamous cell carcinoma tissue (n = 20). No EBV DNA was demonstrated within either normal or malignant epithelium, suggesting that the virus does not persist in normal oral stratified squamous epithelium nor is there any evidence for a role in oral carcinogenesis.

Oral hairy leukoplakia in AIDS patients: an ultrastructural study

Hairy leukoplakia is a specific oral lesion associated with the opportunistic development of Epstein-Barr virus in the oral epithelium. It is now considered to be an early sign of HIV-induced immunosuppression. Four cases of oral hairy leukoplakia (OHL) from the lateral borders of the tongue of male AIDS patients were investigated by transmission electron microscopy. At the ultrastructural level, herpes-like viral particles were detected in the oral lesions of all cases. Indirect immunofluorescence performed on two cases showed the presence of EBV antigens in the nuclei and the cytoplasm of the infected epithelial cells. None of the specimens contained ultrastructural evidence of human papillomaviruses.

Epidemiology, clinical features and prognostic value of HIV-1 related oral lesions

Between February 1987 and February 1990, we studied 737 antibody anti HIV-1 positive (AbHIV+) subjects referred to the Infectious Diseases Institute of the University of Turin (Italy) in order to evaluate types, prevalences, relations with clinical stages, distributions in risk-groups and prognostic significances of HIV-1 related oral lesions. The study evidenced the high prevalence of oral lesions, especially mycoses, in the investigated population: 40.3% of the patients showed, in fact, HIV-1 related oral lesions. The 37 months follow-up of 55 AbHIV+ with oral hairy leukoplakia (HL) and 101 patients with oral candidiasis (OC), demonstrated that the probability of developing AIDS in patient with HL was 0.381 at 15, 0.635 at 25 and 0.824 at 37 months. In the patients with OC the probability was 0.294 at 15 months, 0.524 at 25 and 0.781 at 37 months.

Oral hairy leukoplakia

Oral hairy leukoplakia, usually observed on the lateral border of the tongue, may herald the development of symptomatic human immunodeficiency virus infection. This paper reviews the pertinent clinical features and differential diagnosis, histology, methods of establishing a definitive diagnosis, and management of the patient with this Epstein-Barr virus-associated lesion.

Amplification of Epstein-Barr virus genomic sequences in blood cells, lacrimal glands, and tears from primary Sjögren's syndrome patients

Based on observations of primary Sjögren's syndrome (SS) following acute Epstein-Barr virus (EBV) infection, the authors hypothesized that EBV may play a role in the pathogenesis of SS. This hypothesis was tested by evaluating ten peripheral blood mononuclear (PBMN) cell specimens, ten lacrimal gland biopsies, and five tear specimens from 15 EBV-seropositive primary SS patients for EBV genomic sequences using polymerase chain reaction (PCR). Epstein-Barr virus DNA sequences were detected in 50% of SS PBMN cell specimens and 80% of SS lacrimal gland and tear specimens. In six SS patients, specimens were obtained from two or more sites (i.e., PBMN cell and lacrimal gland and/or tears), and EBV genomic sequences were amplified in the PBMN cells and the lacrimal gland or tears in three of these subjects. The authors previously detected EBV genomes in 32% (11/34) of normal human lacrimal glands from EBV-seropositive donors using PCR and concluded that the normal human lacrimal gland may be a site of EBV persistence; however, they were unable to amplify EBV sequences in DNA from PBMN cells or tear specimens from normal donors. Amplification of EBV DNA in PBMN cells, lacrimal glands, and tears of primary SS patients at a greater frequency (P less than 0.01) than normal controls suggests that EBV may be a risk factor in the pathogenesis of SS.

Fine structure of EBV-infected keratinocytes in oral hairy leukoplakia

We evaluated biopsy specimens of 42 cases of clinically suspected oral hairy leukoplakia for the pattern and frequency of ultrastructural alterations specific to epithelial cells infected with Epstein-Barr virus. Some structures could clearly be identified as Epstein-Barr virus at different stages of assembly, but other intranuclear and cytoplasmic alterations were not conclusively identifiable as any known structure. Keratinocytes producing Epstein-Barr virus contained intranuclear particles of different size and shape; some of them were arranged in a monodispersed pattern and others formed arrays. In contrast, both lesional keratinocytes not producing virus and keratinocytes in uninvolved mucosa contained intranuclear particles reminiscent of perichromatin granules. The nuclei of productive cells also contained marginated chromatin, tubular structures, and, occasionally, crystalline and fibrillar formations as well as enveloped virus. Formations of electron-dense bilayers were seen on both sides of the nuclear membrane. In the cytoplasm of productive cells we observed aggregates of parallel tubules and enveloped electron-dense bodies. Although many of these observations are of diagnostic and pathobiological significance, the morphogenesis, composition, and function of alterations with uncertain morphological identification remain unclear.