New genetics of Burkitt's lymphoma and other non-Hodgkin's lymphomas

Aging hematopoietic stem cells decline in function and exhibit epigenetic dysregulation

Age-related defects in stem cells can limit proper tissue maintenance and hence contribute to a shortened lifespan. Using highly purified hematopoietic stem cells from mice aged 2 to 21 mo, we demonstrate a deficit in function yet an increase in stem cell number with advancing age. Expression analysis of more than 14,000 genes identified 1,500 that were age-induced and 1,600 that were age-repressed. Genes associated with the stress response, inflammation, and protein aggregation dominated the up-regulated expression profile, while the down-regulated profile was marked by genes involved in the preservation of genomic integrity and chromatin remodeling. Many chromosomal regions showed coordinate loss of transcriptional regulation; an overall increase in transcriptional activity with age and inappropriate expression of genes normally regulated by epigenetic mechanisms was also observed. Hematopoietic stem cells from early-aging mice expressing a mutant p53 allele reveal that aging of stem cells can be uncoupled from aging at an organismal level. These studies show that hematopoietic stem cells are not protected from aging. Instead, loss of epigenetic regulation at the chromatin level may drive both functional attenuation of cells, as well as other manifestations of aging, including the increased propensity for neoplastic transformation.

Aging is marked by a decline in function of the entire organism. The effect of age on the regenerative capacity of adult stem cells, which should rejuvenate tissues throughout life, is poorly understood. Bone marrow stem cells, also known as hematopoietic stem cells (HSCs), continuously regenerate the cells that comprise the blood, including the immune system, which fails with age. Here, we show that older HSCs were less able to regenerate the blood system than young HSCs. Paradoxically, the HSC number increased concomitantly, leading to no major difference in overall blood production, even though the immune system did exhibit some defects. To determine why these changes occurred, we looked at global patterns of gene expression in young versus old HSC. Stem cells exhibited an elevated inflammatory response and a decline in factors, called chromatin regulators, that orchestrate DNA accessibility and gene expression. Additional evidence supports the idea that loss of overall gene regulation (epigenetic regulation) is a major event during aging. Whereas much of aging research is concentrated on accumulation of mutations in DNA rather than on global regulatory mechanisms, we speculate that these epigenetic changes could drive many of the manifestations of age. This view also may explain the increased incidence of cancer with age.

In highly purified hematopoietic stem cells from mice aged 2 to 21 months, gene expression analysis indicates a deficit in function yet an increase in stem cell number with advancing age.

Musculoskeletal oncology--advances in cytogenetics and molecular genetics and their clinical implications

Although musculoskeletal malignancies comprise a small group of cancers, a vast number of histological subtypes have been identified attesting to the heterogeneity of this class of tumours and the growing interest in their development. The mode of management for both bone and soft tissue sarcomas has been examined extensively and treatment guidelines have been proposed. Despite the intensive study and multidisciplinary treatment, a substantial proportion of tumours remain recalcitrant to therapy and recur locally and systemically. Improved methods of characterising these tumours may help in understanding their biology. Cytogenetic and molecular genetic techniques allow a subcellular dissection of these malignancies which may aid the identification of mechanisms that are important in tumorigenesis. Already candidate genes have been isolated which may play an important role in the deregulation of proliferation and or the adoption of a malignant phenotype, features which are fundamental in tumour development. By studying the molecular biology and cytogenetics of tumours it may be possible to improve diagnostic and prognostic accuracy thereby minimising over and under treatment.

Flow cytometric analysis of cytokinetics of L3-acute lymphoblastic leukemia/lymphoma

Cell kinetic differences have been described between acute lymphoblastic leukemia with L1 and L2 morphology. We now report cytokinetic and DNA ploidy findings of the rare L3 B-cell leukemia/lymphoma. Flow cytometry analysis of nineteen samples was performed by simultaneous DNA-RNA staining with acridine orange. RNA and DNA indices and cell cycle distributions were calculated. The RNA-index of the G0/G1 cells was 17.9 +/- 8.7 and the number of cells in S phase and S + G2M were 21 +/- 10.6 and 28.0 +/- 13.9 percent respectively. DNA aneuploidy was found in 6/19 (31.6%) and in two cases multiple aneuploid cell lines were observed. DNA aneuploidy and multiple abnormal stemlines adversely affected survival (p less than 0.05), while kinetic parameters did not affect survival (p greater than 0.05). The cytokinetic data are significantly different (S phase and RNA-I; p less than 0.001) than previously reported for the L1 and L2 ALL. Abnormal DNA stemlines were found in cases with no detected cytogenetic abnormalities. This study confirms that L3 ALL is characterized by significantly increased proliferation and provides a means for a flow cytometric identification of this subtype as compared to L1 and L2 ALL.

Acute myelogenous leukemia: current treatment and future directions

Acute myelogenous leukemia (AML), although an uncommon disorder, is a useful prototype for the treatment of malignancies in general. Significant advances have been made in both the understanding and treatment of this disease. In particular, clinically relevant molecular mechanisms of disease in AML are being defined that hold future therapeutic promise. We review the classification and biology of AML and the current treatment controversies in the use of chemotherapy and bone marrow transplantation, and suggest directions for future research.

Immune markers in hematologic malignancies

The precise delineation of biologic traits that distinguish normal hematopoietic cells from their malignant counterparts is of fundamental importance in understanding all aspects of hematologic malignancies. An increasingly sophisticated technologic battery has been utilized to dissect out these differences--primarily utilization of monoclonal antibodies, by immunoperoxidase, immunoalkaline phosphatase and flow cytometric techniques. An even more basic understanding of normal and malignant hematopoietic cells has begun to evolve as molecular biology begins to unravel gene misprogramming by Southern and Northern blot analysis and the polymerase chain reaction. These techniques not only help distinguish a normal cell from a malignant one, but characterize the malignant clone as B-lymphoid, T-lymphoid or myeloid and allow further subcategorization within these broad lineages. These distinctions are vital to the entire spectrum of basic and clinical research involving hematologic malignancies and are assuming an increasingly important role in their diagnosis, prognosis and treatment.

Cytogenetic analysis of 147 cases of non-Hodgkin's lymphoma: non-random chromosomal abnormalities and histological correlations

A prospective cytogenetic study of patients with non-Hodgkin's lymphoma (NHL) presenting to one institution was commenced in 1983 as part of a larger study including histology, immunophenotyping, cytokinetics and survival. 175 patients were studied over 5 years and G-banded karyotypes were successfully obtained in 147. Chromosome abnormalities were detected in 135 cases (92%) with the commonest abnormality being t(14;18)(q32;q21) in 69 cases. Other non-random translocations were much less frequent, i.e. t(11;14) in seven cases and t(8;14) in four cases. Other specific structural changes included partial deletions of 6q (breakpoints ranging within q13-q23), 3q (breakpoints ranging within q21-q27), 1q and 10q22. Chromosome regions highlighted as being frequently involved in structural abnormalities were 11q13-q25, 1p22-p36, 3q21-q27 and 6q13-q23. Several specific recurring breakpoints were identified and these included 14q32, 18q21, 1p36 and 6q21. Frequently occurring numerical abnormalities were gains of chromosomes 3, 7, X and 12. Correlation with histological type showed, as expected, that t(14;18) was present in 89% of follicular lymphoma but also occurred in 30% of diffuse lymphoma. Abnormalities of 11q were correlated with the diffuse histologies as a group, whereas both numerical and structural abnormalities of chromosome 3 correlated with the diffuse large cell lymphoma (DLCL) subtype, and t(11;14) with diffuse small cleaved cell lymphoma (DSCCL). Although not statistically significant, abnormalities of 6q occurred twice as frequently in DLCL than in any other variety. However, several other commonly occurring abnormalities, such as extra copies of chromosomes 7, X, 12 and most of the structural abnormalities of 1p, did not correlate with any histological type. Therefore this large cytogenetic study has confirmed some previously reported correlations between specific chromosome abnormalities and histological subtypes of non-Hodgkin's lymphoma and has also identified some new correlations which may prove useful in the investigation of the biological basis of the disease.

Integrated expert systems and videodisc in surgical pathology: an overview

We present an overview of our 6-year experience in the design of expert systems for anatomic pathology. Our practical goal is to help practicing pathologists with learning, teaching, and the task of diagnosis by providing them with dynamic expert knowledge by means of a personal computer. This project could only be undertaken by first addressing a scientific goal: to characterize the problem-solving strategies that expert pathologists use in making a diagnosis and to state them in the logical terms of computer science. Our approach has been to build systems first for experimentation and then for use. The result of our work is an integrated computer-based approach that handles expert knowledge as formal relationships and morphologic images and that uses a number of logical strategies to provide multiple perspectives on diagnostic tasks. Configured as a pathologist's workstation, this approach can be expected to enhance the performance of trained general pathologists and pathologists in training. Lymph node pathology has been used as the prototype domain for this research, but care has been taken to seek a generalized authoring and inference structure that can be applied to other areas of pathology by changing the contents but not the structure itself. Excursions into various surgical pathology specialties suggest that the ways the system is constructed and exercised is fundamentally robust. Such computer-based expert systems can be expected to generate a new standard in the practice of pathology--based on the "gold standard" of classical morphology, but including the coordinated use of new methods from immunology and molecular biology in a multidisciplinary approach to diagnosis when these techniques are relevant. The benefits from this technology can be expected to be widespread with the evolution, refinement, and diffusion of these systems.

Laboratory and clinical applications of monoclonal antibodies for leukemias and non-Hodgkin's lymphomas

Important insights into leukocyte differentiation and the cellular origins of leukemia and lymphoma have been gained through the use of monoclonal antibodies that define cell surface antigens and molecular probes that identify immunoglobulin and T-cell receptor genes. Results of these studies have been combined with markers such as surface membrane and cytoplasmic immunoglobulin on B lymphocytes, sheep erythrocyte receptors on T lymphocytes, and cytochemical stains. After using all of the aforementioned markers, it is now clear that acute lymphoblastic leukemia (ALL) is heterogeneous. Furthermore, monoclonal antibodies that identify B cells, such as the anti-CD20 and anti-CD19 antibodies in combination with studies of immunoglobulin gene rearrangement, have demonstrated that virtually all cases of non-T-ALL are malignancies of B-cell origin. At least six distinct subgroups of non-T-ALL can now be identified. T-ALL is subdivided by the anti-CD7, anti-CD5, and antibodies that separate T lymphocytes subsets into three primary subgroups. Monoclonal antibodies are also useful in the subclassification of non-Hodgkin's lymphoma, and certain distinct markers can be correlated with morphological classification. Although monoclonal antibodies are useful in distinguishing acute myeloid from acute lymphoid leukemias, they have less certain utility in the subclassification of acute myelogenous leukemia (AML). Attempts to subclassify AML by differentiation-associated antigens rather than by the French-American-British (FAB) classification are underway in order to document the potential prognostic utility of surface markers. Therapeutic trials using monoclonal antibodies in leukemia and lymphoma have been reported. Intravenous infusion of unlabeled antibodies is the most widely used method; transient responses have been demonstrated. Antibodies conjugated to radionuclides have been quite successful in localizing tumors of less than 1 cm in some studies. Therapy trials with antibodies conjugated to isotopes, toxins, and drugs have shown promise. Purging of autologous bone marrow with monoclonal antibodies and complement in vitro has been used in ALL and non-Hodgkin's lymphoma; preliminary data suggest that this approach may be an effective therapy and may circumvent many of the obstacles and toxicities associated with in vivo monoclonal antibody infusion.

The molecular genetics of human non-Hodgkin's lymphoma

There is increasing evidence to implicate oncogenes in the etiology of Burkitt's and non-Burkitt's non-Hodgkin's lymphoma. Some of these oncogenes have been identified because of their location at common breakpoints, some because they have been found by transfection assays to be activated, and some because they have been shown to be expressed in non-Hodgkin's lymphomas. So far there is no consistent pattern of involvement between specific oncogenes and specific subtypes of non-Hodgkin's lymphoma. This may be because more than one oncogene is necessary for transformation.

Immunologic classification of lymphoma and lymphoid leukemia

Important insights into lymphocyte differentiation and the cellular origins of lymphoma and lymphoid leukemia have been gained through the use of monoclonal antibodies that define cell surface antigens and molecular probes that identify immunoglobulin and T cell receptor genes. Results of these studies have been combined with markers such as surface membrane and cytoplasmic immunoglobulin on B lymphocytes, sheep erythrocyte receptors on T lymphocytes, and cytochemical stains. Utilising all of the above markers, it is now clear that acute lymphoblastic leukemia (ALL) is heterogeneous. Furthermore, monoclonal antibodies that identify B cells such as the anti-B1 and anti-B4 antibodies in combination with studies of immunoglobulin gene rearrangement have demonstrated that virtually all cases of non-T-ALL involve B lymphocytes. At least six distinct subgroups of non-T-ALL can now be identified. T-ALL is subdivided by the anti-Leu-9, anti-Leu-1, and additional antibodies that separate T lymphocyte subsets into three primary subgroups. Monoclonal antibodies are also useful in the subclassification of non-Hodgkin's lymphoma, and certain distinct markers can be correlated with morphologic classification.

Subclassification of follicular lymphomas by computerized microscopy

The pilot feasibility study reported was carried out to determine whether computerized morphometry could be used to discriminate between different subtypes of follicular lymphomas. Thirteen cases of follicular lymphomas of the small cell and large cell types were examined by map-guided computerized microscopy. Initially, each specimen was digitized over a 5,120- X -5,120-microns area. Follicle maps depicting well-defined follicles were generated from these digitized images and used to guide a robot microscope to examine follicular center cells using from 20 to 100 fields, each 160 X 160 microns. Mathematical morphology was used to estimate the number of connected regions within each field examined. Based on the assumption that each connected region corresponded to a cell nucleus, it was expected that the number of connected regions found per unit area would correlate with the number of cells per unit area. Three prototypical small cell lymphomas and three prototypical large cell lymphomas were used as a training set to calibrate the methodology. Data obtained on these prototypical cases were used to establish statistical decision boundaries. Seven test cases, judged to be less typical but classifiable by experts, were then examined. Five of the seven were classified correctly, and the remaining two were identified as outliers. These results suggest that subclassification of follicular lymphomas may be aided by computerized microscopy. This pilot feasibility study is currently being expanded using a much larger sample of case material.

Somatic rearrangement of the c-myc oncogene in primary human diffuse large-cell lymphoma

Chromosome translocations involving 8q24, the band to which c-myc has been mapped (Dalla-Favera et al., 1982), are a uniform finding in Burkitt's lymphoma (Bernheim et al., 1981). However, in only a minority of the tumors is the rearrangement of the c-myc locus sufficiently close to the gene to be detected with currently available probes (Dalla-Favera et al., 1983). Approximately 25% of diffuse large-cell lymphomas have also been reported to have translocations involving 8q24 (Mitelman, 1985), but there have been no reports of c-myc rearrangements in this form of non-Hodgkin's lymphoma. We have examined the structure of the c-myc locus in primary tumor tissue of 10 cases of diffuse large-cell lymphoma. In one patient, Southern blot analysis revealed additional c-myc fragments in the tumor DNA but not in the germ-line DNA. Southern blot analysis using probes from both the heavy- and light-chain immunoglobin loci showed that the myc rearrangement was unlikely to involve the immunoglobulin loci in this patient.

Sjögren's syndrome. Proposed criteria for classification

The term "Sjögren's syndrome" (SS) is frequently used to describe the occurrence of keratoconjunctivis sicca and xerostomia in association with an autoimmune disorder. However, well-defined criteria for the classification of SS have not been established, and this diagnosis is being applied to a wide spectrum of conditions, ranging from clear "autoimmune" disease in some patients, to sicca complaints without evidence of a systemic immune process in elderly patients. Here, we review the clinical and laboratory features of patients referred for evaluation of sicca symptoms. In particular, we emphasize the need for care in choosing the site for minor salivary gland biopsy, and we describe the histologic features that aid in the evaluation of these biopsy specimens. In an attempt to identify a population of patients whose conditions might have a common etiopathogenesis and, thus, a common treatment program, we propose the following criteria for a diagnosis of SS: 1) objective evidence of keratoconjunctivis sicca, as documented by rose bengal or fluorescein dye staining; 2) objective evidence of diminished salivary gland flow; 3) minor salivary gland biopsy, obtained through normal mucosa, with the specimen containing at least 4 evaluable salivary gland lobules, and having an average of at least 2 foci/4 mm2; 4) evidence of a systemic autoimmune process, as manifested by the presence of autoantibodies, such as rheumatoid factor and/or antinuclear antibody. The diagnosis of "definite SS" would be made when all 4 criteria are met; the diagnosis of "possible SS" would be made when 3 criteria are present. Specific exclusions for this diagnosis are preexisting lymphoma, graft-versus-host disease, sarcoidosis, and acquired immunodeficiency disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosomal changes in secondary leukemias of childhood and young adulthood

The increasing success of antineoplastic therapy has resulted in a growing number of long-term survivors. These people are at risk for complications of the therapy itself. Among these induced acute nonlymphoid leukemia (ANLL) has been both common and often lethal. We reviewed 72 recently reported patients under 30 years of age at the time of initial diagnosis who developed a secondary, karyotypically defined leukemia. Fifty-eight patients contracted ANLL a mean of 4 1/2 years from the initial diagnosis. In 25 patients, this was preceded by a preleukemic phase characterized by a hypercellular bone marrow with abnormal precursors, often accompanied by peripheral pancytopenia, that lasted a mean of 6 months. Three additional patients died in this preleukemic phase. In all 61, the most common chromosomal abnormalities were numerical errors. Twenty-four patients had a hypodiploid karyotype, most often in those in whom the primary diagnosis was lymphoma (22 of 43). The most common chromosomes missing in whole or in part were number 7 (18 patients), number 5 (8 patients), number 17 (5 patients), and number 21 (4 patients). The anomalies were frequently multiple and complex. Monosomy 7 figured particularly strongly and may be similar to a karyotypically identical myeloproliferative disorder characterized by micromegakaryocytes, giant platelets, and abnormal granulocyte function arising de novo in children. These findings are similar to those in older patients with ANLL induced by environmental carcinogens or antineoplastic therapy. They are different from the karyotypic changes seen in de novo ANLL in children and young adults, suggesting a different etiology. Also, they reinforce the need to find less leukemogenic treatment programs.