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The number of CD8-positive cells in follicular centres of hyperplastic lymph nodes from 20 Danish and Swedish homosexual men with persistent generalized lymphadenopathy and 43 control patients were enumerated in frozen tissue sections immunostained with monoclonal antibody reactive with the CD8-antigen ("cytotoxic-suppressor" T-cell antigen). All the homosexuals were seropositive for HIV and histology showed changes characteristic of the early stage of HIV lymphadenitis. A significant increase (p much less than 0.001) of CD8-positive cells was demonstrated (mean 1,307 per mm2 follicular centre, SD 639) in HIV-related lymphadenopathy compared with the controls (mean 161 CD8-positive cells per mm2 follicular centre, SD 169). The results of this study show that the immunohistological demonstration of a significant increase of CD8-positive cells in the follicles of hyperplastic lymph nodes is suggestive of HIV-related lymphadenopathy.

Hodgkin's disease (HD) has long been suspected to have an infectious precursor, and indirect evidence has implicated Epstein-Barr virus (EBV), a ubiquitous herpesvirus, as a causal agent. Recent molecular studies using EBER in situ hybridization or latency membrane protein-I (LMP-I) immunohistochemistry have identified EBV latent infection in up to 50% of HD tumors. However, the epidemiologic features of these cases have not been examined in detail. To explore the epidemiology of EBV-positive HD so as to understand the role of EBV in HD etiology more clearly, this project accumulated patient data from 14 studies that had applied these EBV assays to HD tumors. With information on age at diagnosis, sex, ethnicity, histologic subtype, country of residence, clinical stage and EBV tumor status from 1,546 HD patients, we examined risk for EBV-positive disease using logistic regression. Forty percent of subjects had EBV-positive tumors, and EBV prevalence varied significantly across groups defined by the study variables. Odds ratios (OR) for EBV-associated HD were significantly elevated for Hispanics vs. whites (OR = 4.1), mixed cellularity vs. nodular sclerosis histologic subtypes (OR = 7.3, 13.4, 4.9 for ages 0-14, 15-49, 50+ years), children from economically less-developed vs. more-developed regions and young adult males vs. females (OR = 2.5). These findings suggest that age, sex, ethnicity and the physiologic effects of poverty may represent biologic modifiers of the EBV association and confirm that this association is strongly but variably linked to histologic subtype. The data augment biologic evidence that EBV is actively involved in HD pathogenesis in some cases but describe epidemiologic complexity in this process.

Fifty formalin fixed, paraffin-embedded cases of T-acute lymphoblastic leukaemia (T-ALL) from 12 bone marrow trephines and 38 lymph nodes were stained with a new monoclonal antibody, 2TL 242, raised against recombinant TAL1 protein. The antibody recognizes TAL-1 polypeptides of molecular weight 39 and 41 kD (full length). In addition, a variety of other leukaemias and lymphomas were also stained with 2TL 242. Twenty-four of the 50 cases of T-ALL showed nuclear positivity, ranging from 10 to 90 per cent of leukaemic cells. A positive staining reaction was nuclear and stippled in pattern. Nuclear staining was not seen in any other type of leukaemia or lymphoma. Five cases of follicular lymphoma showed diffuse cytoplasmic staining of variable intensity. Although some background staining is obtained with this antibody, positive nuclear staining is easily distinguishable. This monoclonal antibody has a potential role in primary diagnosis and in the detection of minimal residual disease in T-ALL.

Epstein-Barr virus (EBV) type B, a less potent transformer of B lymphocytes than type A, has rarely been detected in EBV-associated neoplasms except in AIDS-related lymphomas, in which about 50% of the cases contained this sub-type. In this study we analyzed the association of EBV and the distribution of virus sub-types in Asian non-Hodgkin's lymphoma (NHL) of the upper aerodigestive tract. We studied archival material of 29 NHL cases from Malaysia. B- and T-cell associated antigens were demonstrated by immunohistochemistry, and EBV early RNA EBER-1 was demonstrated using the RNA in situ hybridization technique. EBV was detected in the majority of tumour cells in 11/13 T-NHL but in only 1/16 B-NHL. EBV was sub-typed by single-step polymerase chain reaction of the EBNA-2 gene. This was successful in 9/10 cases of EBER-I-positive tumours and all contained type-A virus only. Our results showed a preponderance of T-cell lymphoma of the upper aerodigestive tract in the ethnic Chinese group of Malaysian patients, and EBV was strongly associated with T-NHL but not with B-NHL. Our results suggest that type-A EBV is the prevalent sub-type in Asian NHL of the upper aerodigestive tract, similarly to findings in Asian nasopharyngeal carcinoma. © 1995 Wiley-Liss, Inc.

Epstein-Barr virus (EBV) can be detected in Hodgkin and Reed-Sternberg (HRS) cells in about one-half of cases of Hodgkin's disease (HD) in Western countries. To determine whether EBV is also associated with HD in a developing country such as China, we studied paraffin sections from 28 Chinese cases of HD for expression of latent membrane protein-I (LMP-I) and EBV-encoded small RNA (EBER-I), using immuno-histology and RNA/RNA in situ hybridization respectively. The cases were selected from a large series of Chinese lymphomas following histological and immunophenotypical revision. EBV gene expression was found in HRS cells in 17/28 cases, and was related to histological sub-type, being present in 10/11 of mixed cellularity, 6/14 nodular sclerosis, 0/1 lymphocytic predominance, 0/1 lymphocytic depletion, and 1/1 unclassified HD. The 2 methods for detecting EBV gene expression gave similar results, except in one case of nodular sclerosis, in which HRS cells were negative for EBER-I, but weakly positive for LMP-I. In 5/12 cases with EBER-negative HRS cells, rare small or medium-sized lymphocytes expressed EBER-I but not LMP-I. These results suggest that (i) Chinese HD is frequently associated with EBV; (ii) the proportional frequency and sub-type distribution of EBV-positive HD are similar in China and in the West; (iii) both LMP-I immunohistology and EBER in situ hybridization reliably detect EBV in HRS cells in routine biopsies, but the former is simpler and less resource-consuming to perform.

Summary. In order to determine the genotypic maturation status of the proliferating lymphoid cells in angioimmunoblastic lymphadenopathy (AILD) and in anaplastic large cell lymphoma of T-type (T-ALC), recombinase activating gene (RAG-1 and RAG-2) expression was assessed in six AILD and five T-ALC cases using a sensitive reverse transcriptase (RT) and competitive (C) polymerase chain reaction (PCR). RAG transcripts were not detectable in nine cases with high proliferating activity, suggesting that in most cases the proliferating cells are derived from mature (rearranged) lymphocytes. However, low levels of RAG transcripts were detected in one AILD and one T-ALC case and are consistent with either an involvement of immature lymphoid precursors in the proliferating pool or a deregulated T-cell maturation pathway with persistence of RAG expression. An association between RAG gene expression and poor response to therapy is possible but has to be tested in larger prospective series.

Haematoxylin and eosin, and Giemsa stained sections from 100 peripheral T-cell lymphomas were examined blind on two occasions by four experienced haematopathologists in order to evaluate the inter- and intra-observer reproducibility of the updated Kiel classification for these malignancies. In all cases, the T-cell phenotype had been established previously in frozen section using a panel of monoclonal antibodies. Analysis by kappa statistics showed poor reproducibility, both overall and for most subtypes, with the exception of large cell anaplastic lymphoma. The distinction between low- and high-grade lymphomas was also unsatisfactory. These results indicate the need for improved precision in the definition of histological categories of peripheral T-cell lymphoma. The reproducibility of the updated Kiel classification for peripheral T-cell lymphomas in its present form is inadequate.

The immunohistological expression of placental alkaline phosphatase (PLAP) and PLAP-like enzyme was studied in frozen sections from a wide variety (n = 254) of normal and malignant tissues using monoclonal antibodies reactive with PLAP (H317) and PLAP/PLAP-like enzyme (H17E2; H315). PLAP/PLAP-like reactivity was seen in normal thymus, and foetal and neonatal testis, and in 21 out of 22 malignant germ cell tumours (GCTs), but was also found in normal endocervix, normal Fallopian tube and in 28 out of 167 non-GCTs (particularly in ovarian and proximal gastrointestinal tract tumours). Positivity for true PLAP (as demonstrated with H317) was seen in term placenta, in endocervix, and in Fallopian tube (but not in other normal tissues) and was commonly found in ovarian and proximal gastrointestinal tract tumours. Reactivity with H317 was unusual in malignant GCTs (2 out of 22 cases). These findings confirm that PLAP/PLAP-like positivity is a highly sensitive immunohistological marker for malignant GCTs, but one which by itself is of only moderate specificity. Furthermore, expression of true PLAP is rare in GCTs and favours instead an origin from the ovary or proximal gastrointestinal tract. The results also indicate that the predominant heat-stable alkaline phosphatase species in normal foetal and neonatal testis, and in thymus has a similar immunohistological profile to that found in malignant GCTs, and is a PLAP-like enzyme ("germ cell alkaline phosphatase") distinct from true PLAP. The occurrence of this marker in GCTs would appear to reflect increased eutopic production of an enzyme present in trace amount in corresponding normal tissues rather than a genuine example of ectopic expression.

The development of monoclonal antibodies and of techniques for demonstrating antigens in situ in frozen tissue sections has been responsible for remarkable progress in diagnostic histopathology. We explored the potential of these techniques when applied to post mortem tissues that were frozen at various intervals after death and stained by monoclonal antibodies using immunoperoxidase technique. The monoclonal antibodies were selected according to their reactivity with essential markers of the lymphatic system and also to their availability. Lymph nodes and splenic tissue from 30 autopsy cases were stained in addition to thymic tissue from eight deceased infants. The antigens proved to be surprisingly well preserved. Staining could be precisely evaluated with UCHT1, OKT6 and anti-Leu-7 antibodies at least 72 h after death; staining with DAKO-pan-B, DAKO-LC and anti-Leu-3a was also very reliable. Antigens expressed by T-suppressor lymphocytes and dendritic reticulum cells were less well preserved. The T8-antigen of suppressor lymphocytes was usually demonstrable in the lymph nodes but less frequently in the splenic tissues. It is concluded that most leucocyte antigens are very resistant to post mortem disintegration, and that they can be reliably interpreted by immunohistological staining using monoclonal antibodies. We therefore recommend this in autopsy specimens in cases where in-vivo examination was not feasible.

Tissue from 53 non-Hodgkin's lymphomas of high-grade malignancy according to the Kiel classification were analysed for cellular immunological markers. In most cases studies were performed in parallel on cell suspensions and cryostat sections. Histologically, the lymphomas were classified as anaplastic centrocytic (four), centroblastic (seven), Burkitt type (three), convoluted-cell type (five) lymphoblastic-unclassified (10), immunoblastic (IBL) (19) and pleomorphic T-cell type (five). Immunological phenotyping resulted in 60% B lymphomas characterized by monotypic surface membrane Ig (SmIg) and/or cytoplasmic Ig (CIg), and 23% T lymphomas with detectable E receptors; 17% of cases were non-expressive (O-type). Unusual SmIg-types were noticed in some monoclonal proliferations. Gamma (gamma) and mu chains occurred simultaneously in four cases; delta chain was the only heavy-chain in one case and a heavy-chain was absent in one case. Cases of IBL were of T-cell type in two cases, and two other cases were non-expressive. The cases of B-IBL expressed CIg in 93%, but the B lymphomas other than B-IBL only in 38%. Receptors for Fc-IgG and C3 were expressed by all major immune phenotypes (B, T, O), but were infrequent in lymphoblastic lymphoma unclassified (O-type). Adoption of immunological techniques to include frozen tissue studies was necessary in order to reach a conclusion regarding the immune phenotype in several cases.

Lymph node biopsies from 75 HIV infected patients (71 homo- and bisexual men, 3 hemophiliacs and 1 woman) were studied using immunohistochemical methods with monoclonal antibodies (Mabs) against B lymphocytes, subsets of T lymphocytes, follicular dendritic cells (FDC) and HIV gag proteins p24 and p18. Histopathological changes were classified as follicular hyperplasia (FH), fragmentation (FF), atrophy (FA) and depletion (FD). Immunohistochemical stainings were quantified with the help of an Image Quantifier (IQ) and the reactivity for respective Mab-defined antigen was related quantitatively to other antigens and histopathological changes. Such measurements showed an increase in FDC in biopsies with FH and FF histology and a decrease in FA and FD cases in comparison with cases with non-HIV related lymphadenopathy. In addition it was found that the decrease in FDC was correlated with an increase in CD8+ within the follicles. Double immunostainings for p24 and various cellular markers showed that p24 was predominantly associated with follicular dendritic cells. Essentially the same findings were observed in the lymph nodes irrespective of risk group. Possible mechanisms involved in follicular involution in HIV-related lymphadenopathy are discussed.

The chromosomal aberrations in tumor cells obtained by bone marrow aspiration from a patient with non-endemic Burkitt's lymphoma (BL) are reported. Twenty percent of the cells contained the marker chromosome 14q+ earlier described in endemic Burkitt's tumors. Other marker chromosomes were dound only in mitoses which did not contain the 14q+.