Differential cytokine expression in EBV positive peripheral T cell lymphomas

AIM

To investigate whether specific cytokines are secreted locally at the tumour site in Epstein-Barr virus (EBV) positive peripheral T cell lymphoma (PTCL).

METHODS

An RNase protection assay system was used to study the differential expression of 21 cytokines in parallel in eight cases of EBV positive non-nasal PTCL, and compared with 11 EBV negative non-nasal PTCLs and three EBV positive nasal natural killer (NK) cell lymphomas.

RESULTS

Among the eight EBV positive cases, interferon gamma (IFN-gamma), lymphotoxin beta (LT beta), interleukin 10 (IL-10), tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta 1 (TGF-beta 1), and IL-1 receptor a (IL-Ra) were frequently detectable. IL-15, IL-6, IL-4, IL-1 beta, TNF-beta, and IL-9 were sporadically detectable. Of the frequently detectable cytokines, IFN-gamma and LT beta were commonly detected in the EBV negative cases. For cases with > 50% EBV encoded small non-polyadenylated RNA (EBER) positive cells, IL-10, TNF-alpha, and TGF-beta 1 were detected in three of three cases, and IL-1Ra in two of three cases. For cases with < 20% EBER positive cells, IL-10 was detected in three of five cases, TNF-alpha in two of four cases, but TGF-beta 1 and IL-1Ra were not detected. Interestingly, IL-6 was detected in two of three cases with > 50% EBER positive cells, but only in one of five cases with < 20% EBER positive cells. For comparison, in NK cell lymphomas, IL-10, TNF-alpha, IL-1Ra, and IL-6 were all detectable, but TGF-beta 1 was not detected at all. Immunohistochemical staining revealed IL-10 in many cells; in contrast, EBV latent membrane protein 1 (LMP1) was only found to be positive in isolated cells.

CONCLUSIONS

Certain cytokines, such as IL-10 and TNF-alpha, might be expressed preferentially in EBV positive peripheral T cell lymphomas. It is likely that such a cytokine environment enhances EBV infection and contributes towards tumorigenesis.

Impaired production of IL-12 in systemic lupus erythematosus. III: deficient IL-12 p40 gene expression and cross-regulation of IL-12, IL-10 and IFN-gamma gene expression

Interleukin 12 (IL-12) is a heterodimer comprising p35 and p40 subunits which are encoded and regulated separately. The authors previously demonstrated deficient IL-12 production in SLE which correlates negatively with disease activity. The present study was designed to determine whether deficiency of IL-12 and excess production of IL-10 and IL-6 in systemic lupus erythematosus (SLE) are due to aberrant regulation at the gene level. Using semiquantitative RT-PCR assay, it was shown that constitutive expression of IL-12 p35 gene is somewhat impaired in SLE compared with controls and that IL-12 p40 mRNA, which was present at low levels in controls, was undetectable in unstimulated SLE peripheral blood mononuclear cells (PBMC). Gene expression of IL-12 p35 and p40 was significantly increased in response to SAC, with significantly lower SAC-induced expression of p40 in SLE patients than controls. SAC-stimulated IL-12 p35 and p40 mRNAs were significantly augmented by interferon gamma (IFN-gamma). Exogenous IL-12 or IFN-gamma significantly inhibited IL-10 gene expression, without affecting IL-6 mRNA or other proinflammatory cytokine mRNA levels. These observations were further confirmed by studies of protein production at the single cell level using ELISPOT assay. Downregulation of IL-12 p40 expression appears to be the cause of IL12 p70 deficiency in SLE. If this defect could be repaired, normalization of IL-12 and IFN-gamma production should reduce excessive IL-10 and prevent pathology.

Preferential type 1-1 cytokine gene expressions in peripheral T-cell lymphomas

In this study, we have investigated whether a pattern of cytokine gene expression can be found in non-Hodgkin's peripheral T-cell lymphoma (PTCL). By using RNase protection assays and RT-PCR, we have systematically studied IL1alpha, IL1beta, IL1-Ra, IL2, IL4, IL5, IL6, IL9, IL10, IL12p35, IL12p40, IL13, IL14, IL15, IFNgamma, IFNbeta, TNFalpha, TNFbeta, LTbeta, and TGFbeta1, TGFbeta2 and TGFbeta3. Twenty-two cases of PTCL inclusive of three nasal NK-cell lymphomas were selected for the study; three cases of reactive lymphoproliferation were included for comparison. Results show that IFNgamma gene expression (key Type 1 cytokine) was frequently detected [18/22 (82 per cent)]. In contrast, IL4 (key Type 2 cytokine) was only detected in 4/22 (18 per cent) of cases (weaker than IFNgamma in three cases). This distinction was also found at the protein level by immunohistochemistry. In addition, TNFbeta and TNFalpha (strongly expressed by Type 1 cells) were almost complimentarily detected [4/19 (21 per cent)] and 12/19 (63 per cent), respectively). In contrast, neither IL5 nor IL13 (strongly expressed by Type 2 cells) were detected at all. However, 14/22 cases expressed IL10, another Type 2 cytokine, which suggests that the autoregulatory feedback loop is stimulated. Compared to the tumour types, the cytokine profiles in the reactive lymphoproliferative types also resembled a Type 1-like pattern but was less striking. The overall result suggested a preferential expression of certain cytokines, and these cytokines may play an important role in pathophysiologic progression in these T-cell disorders.

Malignant lymphoma of the thyroid. A 30-year clinicopathologic experience and an evaluation of the presence of Epstein-Barr virus

Lymphoma of thyroid is uncommon, and Epstein-Barr virus (EBV) is found in many lymphomas. We studied the clinicopathologic characteristics in Hong Kong Chinese and analyzed the presence of EBV in thyroid lymphomas by reviewing data collected during 3 decades. We studied EBV gene expression by in situ hybridization and immunohistochemistry. Primary thyroid lymphomas were found in 23 patients (diffuse large B-cell lymphoma, 18; marginal zone B-cell lymphoma, 4; plasmacytoma, 1), and secondary lymphomas were found in 9 patients (diffuse large B-cell lymphoma, 3; Burkitt lymphomas, 2; Burkitt-like lymphoma, 1; hairy cell leukemia, 1; nasal T-cell and natural killer cell lymphoma, 1; and intestinal T-cell lymphoma, 1). Primary thyroid lymphomas were large (mean, 7 cm), found commonly in older women, and often misdiagnosed as undifferentiated carcinomas. Fine-needle aspiration was not helpful for diagnosis. Fifteen patients had Hashimoto thyroiditis. A history of thyrotoxicosis was found in 3 patients, and coexistence of 3 diseases (papillary microcarcinomas, primary thyroid lymphoma, and Hashimoto thyroiditis) was found 4 patients. The 5-year survival rate for primary thyroid lymphoma was 53%. Combined surgery and radiotherapy seemed to be the best treatment. Secondary thyroid lymphomas often were asymptomatic. EBV messenger RNAs were detected in 1 primary and 1 secondary thyroid lymphoma. The EBV gene expression in primary thyroid lymphoma showed a type II latency pattern. Thyroid lymphomas in Chinese had important clinicopathologic features. EBV may have a role in a subset of cases.

Methylation status of the Epstein-Barr virus major latent promoter C in iatrogenic B cell lymphoproliferative disease. Application of PCR-based analysis

The Epstein-Barr virus (EBV) major latent promoter C drives the expression of viral nuclear proteins important in lymphocyte immortalization and as targets for immune surveillance by cytotoxic T cells. Hypermethylation of the C promoter silences its transcription. This promoter is methylated and silent in Burkitt's lymphoma, Hodgkin's disease, nasopharyngeal carcinoma, and nasal lymphoma. However, it is never methylated in the EBV-immortalized lymphoblastoid cell lines that serve as a model for EBV-associated lymphoproliferative disease. We have analyzed C promoter methylation in iatrogenic EBV-associated B-cell lymphoproliferative disease, mainly posttransplant lymphoma, using a sensitive polymerase chain reaction-based C promoter methylation assay. Our results showed heterogeneity in lymphoproliferative disease with methylation of viral DNA in specimens from 3 of 13 patients. In specimens from two of these patients, only methylated viral DNA was detected and viral nuclear antigen expression was correspondingly restricted. Heterogeneity in C promoter methylation and expression of associated transcripts may be an important determinant of the growth properties of lymphoproliferative lesions and may provide an explanation for the failure of some tumors to respond to withdrawal or reduction of immunosuppressive therapy.

Etiopathogenesis of vitiligo : Are we dealing with an environmental disorder ?

The increasing incidence of vitiligo in this part of the world (4.25%), prompted us to study 5000 fresh vitiligo patients. Several triggering factors were elicitable. Malnutrition and intake of junk food were very common in childhood vitiligo. Intercurrent infections as well as intake of antibotics were also significant, immediately preceding the development of depigmented patches in younger age group. Genetic predisposition was uncommon. Autoimmune disorders were infrequent and usually accompanied late onset vitiligo. For management, vitiligo was classified into VI (active), V2 (quiescent) and V3 (improving) stages. The therapy administered varied in each stage. As a common denominator, all out efforts were made to eliminate possible trigger factors in individual cases throughout the period of treatment, and building the general health to prevent recurrence in future. The study strongly points out that vitiligo is a multifactorial disorder. It can be effectively managed after each patient is individually assessed. Elimination of possible triggering factors may form the mainstay of vitiligo therapy along with controlled pharmacological intervention. The improvement of general resistance of body may bring spontaneous repigmentation.

Autologous thin thiersch's grafts in vitiligo: experience of 8000 cases, 50000 grafts (1959-98) with modified technique in 198 cases in the year 1997-98

The present study, spread over past four decades of experience gathered after operating 8000 stable vitiligo patients, reaffirms the value of thin Thiersch's grafts in treating this disfiguring disease. Under experienced hands, the success rate can be over 95%. However, selection of the patient, quality of the graft and the state of the donor and recipient sites can affect the final outcome.

Comparative analysis of Epstein-Barr virus gene polymorphisms in nasal T/NK-cell lymphomas and normal nasal tissues: implications on virus strain selection in malignancy

Whether particular Epstein-Barr virus (EBV) strains are preferentially selected in malignant diseases remains controversial. Assessment of the importance of strain variation in the pathogenicity of EBV has been hampered principally by the lack of accurate data on the prevalence of virus variants in the normal population. To clarify this issue, a detailed comparative analysis of the EBV genomes contained in normal nasal and nasopharyngeal mucosal tissues and in nasal T/NK-cell lymphoma, which originates at these anatomic sites, was carried out by PCR amplification across the 30-bp deletion and the 33-bp repeat loci in the LMP1 gene and the type-specific polymorphic loci in the EBNA2 and EBNA3C genes and by sequence analysis of the 3' C-terminal region of the LMP1 gene. Whilst the majority of EBV strains in either normal or tumour tissues were type 1 viruses with similar numbers of LMP1 repeats, a marked predominance of LMP1 deletion (del-LMP1) over non-deleted/wild-type LMP1 (wt-LMP1) variants was observed in nasal T/NK-cell lymphoma. Although del-LMP1 variants were also prevalent in the normal carriers of our population, wt-LMP1 was detected at a significantly higher frequency in normal vs. tumour tissues (p = 0.036). More critically, wt-LMP1 variants were found frequently in mixed infection with del-LMP1 variants in the normal carriers. Sequence analysis identified 2 major del-LMP1 (and several wt-LMP1) variants containing signatory nucleotide changes in relation to the prototype B95-8 sequence in both normal and neoplastic nasal tissues. Together, our data provide strong evidence for a selection mechanism for del-LMP1 over the wt-LMP1 variants in tumours.

Phenotypic and cytotoxic characteristics of peripheral T-cell and NK-cell lymphomas in relation to Epstein-Barr virus association

AIMS

We investigated the phenotypic and cytotoxic characteristics of different types of peripheral T-cell and NK-cell lymphomas and correlated the findings of cytotoxic phenotype with Epstein-Barr virus (EBV) association.

METHODS AND RESULTS

Eighty cases of peripheral T-cell and NK-cell lymphomas, classified according to the REAL classification, were investigated for cytotoxic phenotype (by studying T-cell intracellular antigen-1 (TIA-1) expression immunohistochemically) and EBV association (by in situ hybridization for EBV-encoded small non-polyadenylated RNAs), and the results were correlated with the specific clinicopathological types and the immunophenotype with special emphasis on CD56 expression and CD4/CD8 status. Overall, 39/80 cases (49%) expressed TIA-1. Angiocentric lymphoma (23/24 cases; 96%), aggressive NK-cell leukaemia ('large granular lymphocyte (LGL) leukaemia') (3/3 cases; 100%), intestinal T-cell lymphoma (5/6 cases; 83%) and anaplastic large cell lymphoma (4/6 cases; 67%) were the major subtypes showing a cytotoxic phenotype. Only four of the 27 cases (15%) of peripheral T-cell lymphoma, unspecified, were TIA-1+, while all the seven cases of angioimmunoblastic T-cell lymphoma, six cases of mycosis fungoides and one case of adult T-cell lymphoma/leukaemia were TIA-1-.

CONCLUSIONS

Within the group of peripheral T-cell and NK-cell lymphomas, angiocentric lymphoma, aggressive NK-cell leukaemia ('LGL leukaemia'), intestinal T-cell lymphoma and anaplastic large cell lymphoma are the major subtypes displaying a cytotoxic phenotype. The relationships between the cytotoxic phenotype and EBV association, CD56 expression or CD4/CD8 status are secondary to the relationship between cytotoxic phenotype and specific lymphoma subtype.

Epstein-Barr virus infection and its gene expression in gastric lymphoma of mucosa-associated lymphoid tissue

The role of Epstein-Barr virus (EBV) in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) has not been well understood. The aim of the study was to investigate EBV infection and its gene expression in this tumor in order to understand its role in the pathogenesis. EBV infection was screened by in situ hybridization for EBV-encoded non-polyadenylated RNA (EBER ISH) in 79 cases of gastric MALT lymphoma of nonimmunocompromised patients. The expression of EBV proteins [LMP1 (latent membrane protein 1), EBNA2 (EBV nuclear antigen 2), ZEBRA (switch protein encoded by BZLF1 gene)] was studied by immunohistochemistry in EBER-positive cases. EBV was detected with EBER ISH in 15 (19%) of the 79 cases. EBV was found in virtually all tumor cells in 2 cases of high-grade MALT lymphoma (2.5%) (EBV-associated), and was found only in occasional large or small lymphoid cells in 13 cases (16.5%). False positive EBER signal was detected in the mucinous glandular epithelial cells of gastric antrum with FITC-labeled oligonucleotide probe but not with digoxigenin or 35S-labeled riboprobes. Type II latency (EBER+LMP1+ EBNA2-) was detected in both EBV-associated cases. Type III latency (EBER+LMP1+EBNA2+) was also identified in one EBV-associated case besides latency II. Double labeling showed coexpression of LMP1 and EBNA2 in a small number of tumor cells, indicating the presence of type III latency in single cell level. In cases with only occasional EBER-positive large or small lymphoid cells, LMP1 and EBNA2 were not detected. ZEBRA was negative in all the cases. These findings suggest that EBV may contribute to the pathogenesis of a small proportion of high-grade MALT lymphoma, where virtually all tumor cells harbored EBV and the oncogenic viral protein LMP1 was expressed. Moreover, latency III of EBV infection may exist in nonimmunocompromised patient.

Progression of spontaneous lymphomas in SJL mice: monitoring in vivo clonal evolution with molecular markers in sequential splenic samples

SJL mice are an inbred strain with a high incidence of spontaneous lymphomas of the B-cell type. We used molecular markers of clonality to study the process of tumor progression of SJL lymphomas in vivo. This was accomplished at time intervals ranging from 2 to 116 days by initial partial splenectomy (biopsy) followed by spleen sampling at the time of killing (autopsy). Immunoglobulin heavy chain (IgH) gene rearrangement and murine leukemia virus (MuLV) proviral integration patterns were used to study the clonal identities of the sequential tumor pairs in 11 informative mice by Southern blot hybridization. Of these 11 mice, 5 showed the same number of IgH gene rearrangement bands in the matched biopsy-autopsy samples, indicating the persistence of the original lesions. In 2 of 11 mice, a decrease in the number of IgH gene rearrangement bands was seen, consistent with a process of clonal selection in the original oligoclonal population. Another 2 of 11 mice showed an increase in the IgH gene rearrangement bands, indicating the emergence of either a new unrelated clone or, less likely, a subclone with secondary IgH gene rearrangement. The remaining two mice showed differences between the patterns in biopsy and autopsy samples, as assessed by IgH gene rearrangement and the proviral integration analysis. This finding suggests that the biopsied tumor had regressed and new clones had emerged. Tumor development was also associated with an increase in the number of clonal MuLV insertions in all mice except one, in which no non-germline integration band was detected. Of 11 mice, 5 showed an increase in the extent of tumor involvement by microscopic examination of the biopsy and autopsy samples; 3 showed a decrease, whereas 2 showed no change. A change in tumor morphology toward a more dedifferentiated appearance was found in only 1 of 11 mice. Overall, the results did not show a single paradigm that tumor progression followed, rather they indicated a complex and dynamic process of clonal evolution, which is likely to be a major feature of lymphoma progression in vivo.

Emergency department presentations of Lyme disease in children

OBJECTIVE

To review the clinical characteristics and diagnostic evaluation of children with Lyme disease evaluated in an emergency department (ED) in an endemic area.

DESIGN

A retrospective review of the demographic, historical, clinical, and laboratory data of pediatric patients with a final diagnosis of Lyme disease.

SETTING

The pediatric ED of an urban university hospital.

PARTICIPANTS

Children with Lyme disease evaluated during the three-year period from 1992 to 1994.

RESULTS

Twenty-nine children ranging in age from three to 19 years who were diagnosed with Lyme disease subsequent to a visit to a pediatric ED were identified. Four patients had early localized disease with erythema migrans and varying degrees of systemic symptoms. Ten had early disseminated Lyme disease, with multiple erythema migrans, neurologic involvement (including three patients with pseudotumor cerebri), or carditis. Fifteen cases of late Lyme disease with arthritis were identified. Recognition of Lyme arthritis proved particularly difficult; seven children were initially diagnosed as having septic arthritis, six of whom underwent arthrotomy. Marked elevations of the erythrocyte sedimentation rate and synovial fluid white blood cell counts were observed in these patients, making it difficult to distinguish Lyme disease from septic arthritis on the basis of laboratory findings.

CONCLUSION

Lyme disease is an infrequent, often difficult, diagnosis in children who present to an ED. Early disseminated and late disease predominate; classic erythema migrans is uncommon in the ED in comparison with other ambulatory venues. Diagnosis of Lyme arthritis may be difficult; exposure in an endemic area and clinical findings may help distinguish it from septic arthritis. Overall, underdiagnosis of Lyme disease may actually be more of a problem than overdiagnosis in the ED setting. Recognition of Lyme disease by emergency medicine practitioners requires familiarity with its epidemiology and its multiple manifestations.

No evidence of replication error phenotype in primary gastric lymphoma of mucosa-associated lymphoid tissue

Replication error (RER) phenotype, caused by deficiency of DNA mismatch repair genes and revealed by widespread microsatellite instability, has been detected in subsets of a wide variety of solid tumors, but rarely in lymphomas in general. So far, the involvement of RER phenotype in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) type has not been conclusively established. We therefore examined 9 microsatellite loci on 5 chromosomes [D2S123, D3S11, D3S1261, D3S1262, D3S1265, D6S262, D18S559, a CTTT(T) repeat in intron 20 of RBI gene and a CA repeat in p53 locus] in 33 cases of primary gastric MALT lymphoma for evidence of microsatellite instability by polymerase chain reaction using primers end-labeled with [gamma-33P] ATP. Although novel-length allele was observed in 7 of 33 cases (21.2%), none of these 7 cases showed changes in more than one locus. RER phenotype was scored as positive in a case when more than 1 of the 9 examined microsatellite loci showed length alterations. Accordingly, none of the 33 cases had a RER phenotype. This result suggests that the pathogenesis of gastric MALT lymphoma does not involve RER phenotype. It is consistent with the general observations in lymphomas, but is highly in contrast to a previous report showing more than 50% of MALT lymphomas with the RER phenotype.

Frequent detection of Epstein-Barr virus-infected B cells in peripheral T-cell lymphomas

Although Epstein-Barr virus (EBV) positivity has been described in peripheral T-cell lymphomas (PTCLs) in Chinese patients, the cellular lineage of EBV-harbouring cells is unknown. Forty-four cases of PTCL were therefore studied by in situ hybridization (ISH) for EBV-encoded small non-polyadenylated RNA 1 and 2 (EBER), and the lineage of the EBER+ cells was determined by double labelling. The findings were further correlated with the clonality of EBV and the genotype of these EBER+ tumours. The results for the detection of EBV by ISH show that 23 of the 44 cases were EBER+. In 5/23 of the EBER+ cases, EBER was found in around 50 per cent of atypical cells and in 18/23 cases, EBER was found in a subpopulation of atypical cells. Among the EBER+ cases, all 15 tested showed clonal T-cell receptor gene rearrangement by Southern blot hybridization. Double labelling was successfully done in 11 EBER+ cases, and by comparison, EBER+/CD20+ B cells outnumbered the EBER+/CD3+ T cells in all these cases. EBV clonality analysis revealed that EBV was monoclonal in six EBER+ cases and biclonal in three cases. With the predominance of EBV+ B cells over EBV+ neoplastic T cells being observed in most of these cases, it is possible that the EBV-infected clonal population may be of B-cell lineage. This was supported in some cases where a faint clonal band was seen over a background smear in the gene rearrangement study of immunoglobulin heavy chain gene by polymerase chain reaction (PCR), indicating a minor B-cell clone. It is concluded that in EBV+ PTCL, EBV is preferentially localized in B cells rather than neoplastic T cells. The neoplastic T cells may support the clonal proliferation of a subpopulation of EBV+ B cells in PTCLs.

Mutation of the 5' noncoding region of the BCL-6 gene in low-grade gastric lymphoma of the mucosa-associated lymphoid tissue

BCL-6 gene rearrangement and hypermutations were investigated in four Hong Kong Chinese patients with low-grade gastric lymphoma of the mucosa-associated lymphoid tissue (MALToma). The former was studied by Southern analysis and the latter by the technique of polymerase chain reaction and denaturing gradient gel electrophoresis. BCL-6 gene rearrangement was not detectable in any of the four cases. However, mutations at both the E1.11 and E1.12 segments of the 5' noncoding region of the BCL-6 gene were found in two patients. This preliminary observation suggests that the mutations of the 5' noncoding region of the BCL-6 gene rather than gene rearrangement may be playing a more important role in the tumorigenesis of low-grade gastric MALToma. Further confirmation of this finding by studying a larger number of patients will be required.

Expression of insulin-like growth factor II mRNA in hepatocellular carcinoma

Insulin-like growth factor II (IGF-II) is a mitogenic polypeptide closely related to insulin. Its gene has complex regulation of transcription, resulting in multiple mRNA initiated by different promoters. To study its role in hepatocarcinogenesis, we examined the expression of IGF-II mRNA in hepatocellular carcinomas (HCC) and correlated it with the pathological features of the tumours. Using northern blot analysis, transcription of the normal adult promoter was repressed in all but two of the 30 HCC. Instead, there was re-expression of two foetal transcripts (6 and 5 kb) in 12 tumours. In contrast, most (93.3%) of the non-tumorous livers showed expression of adult transcript only, and there were three livers demonstrating expression of foetal transcripts in addition to the adult one. There was a significant association of IGF-II expression with direct tumour invasion into the adjacent liver parenchyma but foetal expression did not influence other parameters directly related to tumour invasiveness, including venous permeation, formation of tumour microsatellites and positive resection margin. Besides, IGF-II expression was significantly more frequently seen in tumours from older patients. To conclude, repression of normal adult promoter and re-expression of foetal promoters of IGF-II are common events in HCC. The observation that foetal IGF-II expression was significantly more frequent in older patients suggests that spontaneous foetal expression of IGF-II late in life may promote the growth of tumours which have already arisen through other mechanisms, but foetal re-expression itself is not enough to contribute to tumour progression.

Clonality of lymphomas at multiple sites in SJL mice

SJL mice are an inbred strain of mice with a high incidence of spontaneous lymphomas of B-cell type often involving multiple abdominal organs, and are therefore a useful model for studying the clonal relationship among lymphomas at multiple sites. Thirteen SJL mice with well-developed tumors were killed at a median age of 56 weeks. Autopsy samples were taken from various enlarged lymphoid organs, and the histologic appearance of lymphomas was recorded. Using rearrangements of immunoglobulin genes (heavy and kappa-light chain genes) and integration patterns of murine leukemia virus as clonal markers, 7 of the 13 informative mice showed complete clonal identity among the different sites selected from each mouse; 5 of 13 mice demonstrated at least one shared clonal band with one or more markers being different among the different sites. The histologic appearance of the lymphomas from the various sites was found to be heterogeneous, even when there was clonal identity. These findings suggest that SJL lymphomas in multiple sites within one mouse are usually derived from a single clone but may show development of subclones within a major clonal population, thus supporting the notion that clonal evolution is a common event in the course of development of lymphoid neoplasia.

Solitary neurofibroma of the larynx

Neurofibromas of the larynx occur sporadically or in association with von Recklinghausen's disease. The first reported case of isolated endolaryngeal neurofibroma in 1925 1 has been followed by occasional reports. 2–4 The aryepiglottic folds are the usual sites of occurrence, and the tumor frequently obscures the endolarynx. Following is a case of solitary neurofibroma of the larynx; preoperative diagnosis was difficult to make, and the tumor was treated surgically.

Bcl-6 gene hypermutations in diffuse large B-cell lymphoma of primary gastric origin

The presence of the bcl-6 gene hypermutation was studied in 40 Hong Kong Chinese patients with diffuse large B-cell lymphoma. The primary sites of involvement were nodal in 18 cases and gastric in 22. Hypermutations at the E1.11 segment of bcl-6 gene were detectable in 16/22 (73%) primary gastric and 4/18 (22%) primary nodal lymphoma (P<0.01). Three of the 22 cases of primary gastric but none of the nodal lymphoma had mutations at E1.12. The proportion of hypermutated cases in the group with bcl-6 gene rearrangement was similar to that of the germ-line group (70% v 75%). High frequency of bcl-6 gene hypermutations was found in diffuse large B-cell lymphoma of the stomach and they were independent of rearrangement of the gene as detected by Southern analysis. Unlike gene rearrangement, hypermutations of the bcl-6 gene did not appear to carry any prognostic significance clinically.

Prevalence of six types of human papillomavirus in inverted papilloma and papillary transitional cell carcinoma of the bladder: an evaluation by polymerase chain reaction

AIMS

To study the prevalence of high risk oncogenic human papillomaviruses (HPV) in inverted papilloma and papillary transitional cell carcinoma of the bladder.

METHODS

Ten cases of inverted papilloma and 20 cases of papillary transitional cell carcinoma of the bladder from Chinese patients in Hong Kong were examined for the presence of HPV type 6, 11, 16, 18, 31, and 33 genomes using the polymerase chain reaction and HPV type specific primer probe combinations on paraffin wax embedded biopsy specimens.

RESULTS

Of the 10 cases of inverted papilloma, cases 1 and 6 showed the presence of HPV types 16 and 18, respectively. Six of the 20 papillary transitional cell carcinomas were positive for HPV type 18. The other HPV types were not detected.

CONCLUSIONS

HPV type 18 was found in 60% and 30% of cases of inverted papilloma and papillary transitional cell carcinoma of the bladder, respectively. These tumours were rarely associated with HPV types 6, 11, 16, 31, and 33. The role of HPV type 18 in oncogenesis of inverted papilloma and transitional cell carcinoma of the bladder requires further studies.

Nasal T/natural killer (NK)-cell lymphomas are derived from Epstein-Barr virus-infected cytotoxic lymphocytes of both NK- and T-cell lineage

The cellular nature of nasal T/natural killer (NK)-cell lymphomas (NLs) remains controversial. It is still debatable whether these represent T-cell lymphomas with extensive loss of surface antigens or are, in fact, true NK-cell lymphomas. They are associated closely with Epstein-Barr virus (EBV), to the extent that EBV-encoded small non-polyadenylated RNAs (EBER) expression can be used as a marker for the neoplastic cells. The cell lineage of this group of lymphomas was examined further by correlating immunophenotype, genotype and EBV status with the expression of cytotoxic granule-associated proteins, perforin and T-cell intracellular antigen-1 (TIA-1) in 13 cases of NL. Combined immunophenotypic and gene rearrangement analyses demonstrated that NLs can be identified clearly as either NK-cell or T-cell tumours. Nasal NK-cell lymphomas lacked clonal rearrangement of both T-cell receptor (TCR) gamma and immunogloulin heavy chain (IgH) genes and were either CD3(Leu4)-CD56+ (8 cases) or CD3(Leu4)+CD56+ (2 cases), whereas nasal T-cell lymphomas had rearranged TCRgamma and germ-line IgH genes and were either CD3(Leu4)+CD56+ (2 cases) or CD3(Leu4)+CD56- (1 case). Immunohistochemical (IH) studies showed that both perforin and TIA-1 were expressed universally in NL, irrespective of NK- or T-cell lineage. Dual labelling of TIA-1 by IH and EBER by in situ hybridisation demonstrated that the granule proteins were expressed predominantly by the EBER+ tumour cells. Our results indicate that NLs are derived from EBV-infected cytotoxic lymphocytes of both NK- and T-cell lineage. We postulate that cytotoxic lymphocytes generated during the cellular immune response to EBV infection or re-activation at the nasal region themselves may become targets for EBV infection and subsequent transformation.

High incidence of BCL-6 gene rearrangement in diffuse large B-cell lymphoma of primary gastric origin

The incidence of BCL-6 gene rearrangement was studied in 39 Hong Kong Chinese patients with diffuse large B-cell lymphoma. The primary site of involvement was nodal in 18 cases and gastric in 21 cases. Clonal BCL-6 gene rearrangement was found in 17% of the patients with primary nodal and 48% with primary gastric lymphoma (p = 0.05). The clinical characteristics and treatment outcome of the 21 patients with primary gastric lymphoma were analyzed according to the BCL-6 status. Significantly more patients in the germline BCL-6 gene group had advanced stage (II, III and IV) of disease. Complete remission rate following primary therapy appeared to be higher for the positive rearrangement group (70% versus 36%), but it was not statistically significant. Those with a rearranged BCL-6 gene also appeared to have better survival at 5 years (58% versus 36%) but the difference was also not statistically significant. On the other hand, patients being classified as low risk according to the International Prognostic Index had significantly better survival at 5 years (89% versus 9%, p = 0.0001). We concluded that BCL-6 gene rearrangement was more commonly found in diffuse large B-cell lymphoma of primary gastric origin than its nodal counterpart and it may be playing a more important role in the pathogenesis of gastric large B-cell lymphoma. There was a trend that the BCL-6 gene rearrangement was associated with a more favorable outcome in patients with gastric large B-cell lymphoma but the difference was not statistically significant.

Gene expression of hypothalamic somatostatin and growth hormone-releasing hormone in dexamethasone-treated rats

Supraphysiological doses of glucocorticoids inhibit growth hormone (GH) secretion in man and experimental animals. We investigated whether glucocorticoids inhibit GH secretion through changes in the gene expression of GH, hypothalamic somatostatin (SS) and GH-releasing hormone (GHRH), and whether such changes vary with the dose and duration of glucocorticoid excess. Male rats, 6 weeks of age, were treated with injections of either saline or different doses of dexamethasone (40, 200, 500 or 1,000 micrograms/kg/day) intraperitoneally for 3 or 8 days. Total RNA extracted from the anterior pituitary and hypothalamus was analyzed by Northern blot hybridization. SS mRNA level was also assessed in smaller hypothalamic fragments containing predominantly the periventricular and paraventricular nuclei, and by in situ hybridization. A biphasic effect on SS mRNA levels was observed such that a significant increase (p < 0.001) was demonstrated in the periventricular nucleus after 3 days of dexamethasone 1,000 micrograms/kg/day, but a reduction in hypothalamic SS mRNA was seen after 8 days for all doses employed (p < 0.05 or p < 0.01). On the other hand, hypothalamic GHRH mRNA levels showed a reduction which appeared to increase with the dose and duration of treatment and became statistically significant after 8 days at doses > or = 200 micrograms/kg/day (p < 0.05). Pituitary GH mRNA levels were increased after 3 days at doses > or = 500 micrograms/kg/day (p < 0.05) but showed no significant change at all doses after 8 days. We conclude that glucocorticoid excess is associated with changes in the gene expression of GH, hypothalamic SS and GHRH, which vary with the dose and duration of glucocorticoid treatment. Glucocorticoids inhibit GH secretion in vivo through a reduction in hypothalamic GHRH gene expression and, in animals with shorter duration of glucocorticoid excess also through an increase in SS gene expression in the periventricular nucleus.