Evaluation of the impact of fetal fibronectin test implementation on hospital admissions for preterm labour in Ontario: a multiple baseline time-series design.

OBJECTIVE: To determine the impact of a health system-wide fetal fibronectin (fFN) testing programme on the rates of hospital admission for preterm labour (PTL). DESIGN: Multiple baseline time-series design. SETTING: Canadian province of Ontario. POPULATION: A retrospective population-based cohort of antepartum and delivered obstetrical admissions in all Ontario hospitals between 1 April 2002 and 31 March 2010. METHODS: International Classification of Diseases codes in a health system-wide hospital administrative database were used to identify the study population and define the outcome measure. An aggregate time series of monthly rates of hospital admissions for PTL was analysed using segmented regression models after aligning the fFN test implementation date for each institution. MAIN OUTCOME MEASURE: Rate of obstetrical hospital admission for PTL. RESULTS: Estimated rates of hospital admission for PTL following fFN implementation were lower than predicted had pre-implementation trends prevailed. The reduction in the rate was modest, but statistically significant, when estimated at 12 months following fFN implementation (-0.96 hospital admissions for PTL per 100 preterm births; 95% confidence interval [CI], -1.02 to -0.90, P = 0.04). The statistically significant reduction was sustained at 24 and 36 months following implementation. CONCLUSIONS: Using a robust quasi-experimental study design to overcome confounding as a result of underlying secular trends or concurrent interventions, we found evidence of a small but statistically significant reduction in the health system-level rate of hospital admissions for PTL following implementation of fFN testing in a large Canadian province.

Low-dose chemotherapy and rituximab for posttransplant lymphoproliferative disease (PTLD): a Children's Oncology Group Report.

Optimal therapy for posttransplant lymphoproliferative disease (PTLD) remains problematic. A phase II trial adding rituximab to a low-dose cyclophosphamide and prednisone regimen was conducted for pediatric patients with Epstein-Barr virus (EBV) (+), CD20 (+) PTLD. Fifty-five patients were enrolled. Toxicity was similar for cycles of therapy containing rituximab versus those without. The complete remission (CR) rate was 69% (95% confidence interval (CI); 57%-84%). Of 12 patients with radiographic evidence of persistent disease at the end of therapy, eight were in CR 28 weeks later without further PTLD therapy. There were 10 deaths, 3 due to infections while receiving therapy and 7 from PTLD. The 2-year event-free survival (alive with functioning original allograft and no PTLD) was 71% (95% CI: 57%-82%) and overall survival was 83% (95% CI: 69%-91%) with median follow-up of 4.8 years. Due to small numbers, we were unable to determine significance of tumor histology, stage of disease, allograft type or early response to treatment on outcome. These data suggest rituximab combined with low-dose chemotherapy is safe and effective in treating pediatric with EBV (+) PTLD following solid-organ transplantation.

Do molecules matter more than morphology? Promises and pitfalls in parasites.

Systematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences--morphological and molecular data--as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.

Human myeloid leukemic cell (HL-60) autostimulator: relationship to colony-stimulating factor.

The human promyelocyte leukemic cell line HL-60 secretes a glycoprotein factor which stimulates HL-60 and myeloid cell growth and colony formation in vitro. Functional and biochemical studies indicate this autostimulatory activity (ASA) is distinct from colony-stimulating factor (CSF) activities reported previously. Human CSF I, CSF II, and HL-60 ASA stimulated HL-60 growth and colony formation. The ASA also demonstrated CSF activity for both granulocyte and macrophage colonies when assayed on normal mouse and human bone marrow cells. The ASA glycoprotein was partially purified 1200-fold to an apparent molecular weight of 25,000 on G-75 filtration and a pl of 4.9 after neuraminidase treatment. Serological cross-reactivity between human CSF I and HL-60 ASA was detectable by immune precipitation and neutralization of biological activity with rabbit anti-CSF I antibodies. The cross-reactive anti-CSF I antibodies also inhibited spontaneous HL-60 colony formation in vitro in the absence of exogenous CSF, ASA, or anti-HL-60 antibody activity. These results indicate that HL-60 ASA is an endogenous growth factor similar to CSF that may be required for HL-60 growth in vitro.

Next-generation IgVH sequencing CLL-like monoclonal B-cell lymphocytosis reveals frequent oligoclonality and ongoing hypermutation.

Chronic lymphocytic leukemia (CLL) develops from CLL-like monoclonal B-cell lymphocytosis (MBL) which represents a low-level asymptomatic expansion of cells that phenotypically resemble CLL. Although antigen selection plays a key role during CLL development, it is not known whether this occurs in early MBL or only during progression to CLL. Recent studies suggested that MBL sometimes displays oligoclonality, but these used techniques with limited sensitivity and specificity and were not conclusive. In this study, we combine cell sorting and next-generation sequencing of rearranged immunoglobulin heavy chain variable (IgVH) genes to thoroughly assess the VH repertoire and oligoclonality of purified MBL cells. Clonal functional rearrangements or clonotypes were identified in 29 of 30 sequenced cases, with 7 or 24% having two clonotypes with unrelated CDR3 sequences. In four of the seven cases with unrelated clonotypes, VH segments from the same family were used. In addition, 6 of 29 cases showed clear evidence of ongoing VH gene hypermutation with three of these being among the seven with unrelated clonotypes. This study conclusively shows that MBL cases often contain multiple B-cell clones, the first to report ongoing VH gene mutation in MBL, and that antigen selection appears to occur in early MBL.

Linkage of the isoprenoid biosynthetic pathway with induction of DNA synthesis in mouse lymphocytes. Effects of compactin on mitogen-induced lymphocytes in serum-free medium.

Concanavalin A induction of DNA synthesis in mouse spleen lymphocytes cultured in serum-free medium was shown to be very sensitive to inhibition by compactin (ML-236B), a specific competitive inhibitor of hydroxymethylglutaryl-CoA reductase. As low as 0.1 microM compactin could give 98% inhibition of mitogen induction of a 5.10(6) cells/ml culture. This inhibition could be reversed completely by addition of exogenous mevalonate, but could not be reversed by either exogenous cholesterol or isopentenyladenine. Oxygenated sterol inhibition of mitogen-induced DNA synthesis could be reversed by cholesterol or by mevalonate, whereas cyclic AMP inhibition could not be reversed by either compound. These results suggest that endogenous cholesterol production is a necessary but not sufficient factor co-ordinated with mitogen-induced DNA synthesis, and that the presence of some additional product of mevalonate metabolism is involved also. Isopentenyladenine, though, did not have as significant effect of alleviating any of the above inhibitions. Since mevalonate could not relieve cyclic AMP inhibition, but could overcome compactin inhibition, cyclic AMP inhibition cannot be explained as due only to blockage of mevalonate production.

Large-cell lymphoma arising in the mediastinum in children and adolescents is associated with an excellent outcome: a Children's Cancer Group report.

PURPOSE: Large-cell lymphoma (LCL) arising in the mediastinum (LCL-M) is a heterogeneous group of non-Hodgkin's lymphoma (NHL) that includes B-cell lymphomas as well as T-cell lymphomas, including anaplastic LCL. LCL-M is well recognized in young adults but is less well characterized and infrequent in children and adolescents. METHODS: A retrospective review of Children's Cancer Group therapeutic studies for nonlymphoblastic lymphomas (CCG-551, CCG-503, CCG-552, and CCG-5911) identified 20 patients with LCL-M, representing 7.2% of all LCLs classified by central pathology review. RESULTS: The patients ranged in age from 4 to 19 years (median, 12.5 years; mean, 12 years); 55% of the patients were male. Although a variety of chemotherapy regimens were used, response was excellent, with all 20 patients (100%) achieving a complete response. Four patients (20%) experienced relapse locally or in distant sites including brain and kidney. One patient died of sepsis during therapy. For the 20 patients with LCL-M, the product-limit estimated 5-year event-free survival (EFS) and 5-year overall survival (OS) rates are 75% +/- 10% and 85% +/- 8%, respectively. For disseminated LCLs (192 cases), the EFS and OS rates were 50% +/- 4% and 63% +/- 4%, respectively, which differ significantly from the those of the LCL-M cases (EFS, P =.025; OS, P =.034). The 5-year EFS and OS rates for patients with localized LCL (67 cases) were 92 +/- 3% and 97 +/- 2%, respectively. CONCLUSION: LCL-M is a heterogeneous group of NHLs that makes up approximately 7.2% of LCL in children and adolescents. Response to therapy and OS in this young age group seems excellent and superior to that of disseminated LCLs but inferior to that of other localized LCL. Future studies of LCL-M will evaluate short intense chemotherapy administered without radiation therapy.

Diversity of the apoptotic response to chemotherapy in childhood leukemia.

Apoptosis is the primary mechanism through which most chemotherapeutic agents induce tumor cell death. The purpose of this study was to determine the extent to which blasts from children with leukemia undergo a uniform apoptotic death pathway in vivo. The expression of pro- and anti-apoptotic proteins p53, p21, MDM-2, BCL-2, BCL-X(L), BCL-X(S), and BAX, and caspase-3 activity was determined in circulating blasts collected from the peripheral blood of children with leukemia prior to, and at serial time points following chemotherapy. Culturing blasts ex vivo for 12 h assessed spontaneous apoptosis and the increment induced by chemotherapy. Baseline apoptosis varied between 3% and 29%. Twenty-four hours following chemotherapy the increase in the percentage of cells undergoing apoptosis ranged from <1% to 38%. Eleven of 20 patients who received initial treatment with a p53-dependent drug showed an increase in p53 expression. In these patients, the levels of p53 target genes were also increased. A uniform pattern of BCL-2 family protein expression was not observed and only a minority of samples showed a change that would favor apoptosis. We conclude that that the initial apoptotic response to chemotherapy in children with leukemia is variable involving both p53-dependent and p53-independent pathways.

1,25-Dihydroxyvitamin D3 induces monocytic differentiation of the PLB-985 leukemic line and promotes c-fgr mRNA expression.

1,25-dihydroxyvitamin D3 [1,25(OH)2D] is known to stimulate maturation of the human promyelocytic line HL-60 and murine bone marrow precursor cells along a monocyte/macrophage pathway. In this study, the steroid's effects on the PLB-985 leukemic line were examined. We found that 1,25(OH)2D induces monocytic differentiation of PLB-985 as manifested by morphological appearance, histochemical staining, and changes in cell surface antigen expression. Additionally, there was acquisition of functional monocyte characteristics including phagocytic activity and superoxide anion production via the respiratory burst pathway. Steady state levels of mRNA derived from the leukocyte-specific proto-oncogene c-fgr were also increased by the steroid. Thus, 1,25(OH2)D effectively differentiates PLB-985 cells along a monocytic pathway, providing a useful model of macrophage differentiation.

Pattern of colony-stimulating activity in HL-60 cells after phorbol-ester-induced differentiation.

HL-60 cells secrete an autostimulatory activity (ASA) that appears to be required for their growth in vitro. The purpose of this study was to examine the pattern of colony-stimulating activity in conditioned media of HL-60 after induction of differentiation by the phorbol ester phorbol-12-myristate-13-acetate (PMA). PMA-induced differentiation to monocyte-macrophage cells was accompanied by persistence of ASA secretion and the appearance of new species of colony-stimulating activities similar in properties to human CSF I and CSF II. Thus the secretion of ASA by HL-60 appears to be a characteristic property of these cells that is maintained after terminal differentiation.

1,25-Dihydroxyvitamin D3 modulates colony-stimulating factor-1 receptor binding by murine bone marrow macrophage precursors.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] has been shown to be a potent agent for monocyte/macrophage differentiation in leukemic cell lines. This study examines the differentiational effects of 1,25-(OH)2D3 in authentic murine bone marrow immature uncommitted precursor cells collected by pretreatment of murine bone marrow with 5-fluorouracil (5-FU). Early precursor cells, collected 1 day after 5-FU treatment, are characterized by low expression of the colony-stimulating factor-1. (CSF-1) receptor and dependence on both CSF-1 and interleukin-1 for growth. Intermediate precursors were collected 5 days after 5-FU treatment and required either CSF-1 or interleukin-3 for growth. Intermediate precursors expressed relatively higher levels of the CSF-1 receptor. Addition of 1,25-(OH)2D3 to these populations inhibited proliferation, as measured by [3H]thymidine incorporation and soft agar colony assay. Furthermore, 1,25-(OH)2D3 caused a more rapid appearance of the CSF-1 receptor in early precursor cells in a dose-dependent metabolite-specific manner. Conversely, CSF-1 receptor expression was decreased in intermediate precursors treated with the steroid. This decrease in receptor expression was also dose dependent and metabolite specific. These findings demonstrate that 1,25-(OH)2D3 1) targets to authentic bone marrow macrophages at various stages of differentiation and 2) modulates expression of the CSF-1 receptor, a protein which, in turn, regulates monocytic maturation.

1,25 dihydroxyvitamin D3 stimulates differentiation of committed murine bone marrow-derived macrophage precursor cells.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] and macrophage colony-stimulating factor (M-CSF) both accelerate differentiation of marrow macrophages from which osteoclasts are derived. Previously, we showed that the steroid's effect on early macrophage precursors may be mediated through M-CSF, as the steroid enhances cytokine receptor expression. In contrast, 1,25-(OH)2D3 blunts M-CSF receptor expression on more mature, yet still pluripotential, hematopoietic precursors. Extending these observations to marrow cells committed to macrophage differentiation, we found that 1,25-(OH)2D3 causes a marked decrease in cellular proliferation despite a 2- to 3-fold increase in [125I]M-CSF binding in a similar dose-dependent metabolite-specific manner. Scatchard analysis demonstrated that increased binding reflects increased receptor capacity without an alteration in affinity. Steroid-induced M-CSF receptor enhancement reflects acceleration of protein appearance rather than overexpression, as treated and untreated cells ultimately exhibit equivalent binding. Increased M-CSF receptor expression is mirrored by increased c-fms messenger RNA levels, and actinomycin D or cycloheximide experiments indicate that new receptor synthesis, rather than mobilization of intracellular pools, is required. Thus, 1,25-(OH)2D3 differentially impacts on M-CSF receptor expression throughout the spectrum of bone marrow macrophage differentiation.

Age-related bone loss in mice is associated with an increased osteoclast progenitor pool.

Age-associated osteopenia has been documented to occur in mice and, therefore, provides a model system whereby mechanisms of bone loss can be assessed in vivo and in vitro. One such mechanism, that could explain the increased resorptive activity seen in some forms of osteopenia, is an age-associated increase in the osteoclast precursor pool and osteoclastogenic formation. To test this hypothesis, we studied the bone marrow composition of aged (24 months) mice to determine if increased numbers of monocyte/macrophage/osteoclast precursor cells (MMOPC) were present when compared to young (4-6 months) animals. Our data show a moderate increase of 20-30% more hematopoietic cells obtained from the long bones of the aged animals. However, both liquid and semi-solid culture techniques demonstrate an approximately 2-3.5-fold increase in the numbers of plastic adherent macrophages or mononuclear colonies in bone marrow derived from the aged mice when stimulated by interleukin-3 (IL-3), granulocyte-macrophage colony stimulating factor (GM-CSF) or macrophage colony stimulating factor (GM-CSF), indicating a preferential increase in MMOPCs. In addition, cells derived from the aged mice show higher levels of cytokine stimulated incorporation of [3H]-thymidine and [3H]-leucine, with increased protein synthesis seen up to 7 days after cytokine stimulation, suggesting that these cells also have an enhanced sensitivity to cytokines.(ABSTRACT TRUNCATED AT 250 WORDS)

Are myogenin and myoD1 expression specific for rhabdomyosarcoma? A study of 150 cases, with emphasis on spindle cell mimics.

Rhabdomyosarcoma (RMS), the most common soft tissue sarcoma of childhood, displays a variety of histologic patterns. Immunohistochemistry is used extensively to distinguish RMS from its mimics. Myogenin and MyoD1, myogenic transcriptional regulatory proteins expressed early in skeletal muscle differentiation, are considered sensitive and specific markers for RMS and are more specific than desmin and muscle-specific actin and more sensitive than myoglobin. Previous studies have focused on expression of myogenin and MyoD1 in small round cell tumors. This study assesses myogenin and MyoD1 in rhabdomyosarcoma subtypes and spindle cell tumors considered in the differential diagnosis of RMS. Formalin-fixed, paraffin-embedded archival tissue from 32 RMS, 107 non-RMS, and 11 benign skeletal muscle samples was stained for myogenin and MyoD1 with standard immunohistochemical techniques. Nuclear positivity was scored on a three-tiered scale. All RMSs expressed myogenin. Alveolar RMS (ARMS) showed strong nuclear staining, especially in tumor cells lining fibrous septae and perivascular regions. In cases with a subtle alveolar architecture on routinely stained sections, myogenin highlighted and enhanced visualization of the alveolar morphologic pattern. Embryonal RMSs (ERMSs) were more variable in myogenin staining pattern and intensity. No cases of nodular fasciitis, malignant fibrous histiocytoma, malignant peripheral nerve sheath tumor, inflammatory myofibroblastic tumor, myofibrosarcoma, leiomyoma, leiomyosarcoma, or alveolar soft part sarcoma stained for myogenin. Focal nuclear reactivity was seen in desmoid (2 of 10), infantile myofibromatosis (2 of 10), synovial sarcoma (1 of 10), and infantile fibrosarcoma (2 of 10). Non-neoplastic skeletal muscle fiber nuclei stained positively for myogenin in both tumor-associated samples (25 of 40) and benign skeletal muscle samples (5 of 11). Although all RMSs were immunoreactive for MyoD1, cytoplasmic and nonspecific background staining and reactivity of nonmyoid tissues hindered its practical utility in paraffin-embedded samples in this study. Although myogenin is a highly sensitive and specific marker for RMS, it is rarely seen in other spindle cell soft tissue tumors. As previously reported, ARMS stained more strongly than ERMS. In contrast to previous studies, rare non-RMS (7 of 107) displayed focal nuclear reactivity, and entrapped atrophic or regenerative skeletal muscle fibers also stained positively. Although these are potential pitfalls in the interpretation of myogenin, careful attention to morphology and other features, to the relative paucity of myogenin-positive nuclei in non-RMS. and to the presence of entrapped muscle fibers should prevent incorrect interpretation. Because the extent of myogenin expression in RMS is much greater than in non-RMS, it is a very useful marker when interpreted in the context of other clinicopathologic data.

Proliferation and cellular phenotype in lymphomatoid granulomatosis: implications of a higher proliferation index in B cells.

Pulmonary involvement by lymphomatoid granulomatosis (LYG) is characterized by nodules of a polymorphous lymphoreticular infiltrate with necrosis, angioinvasion, and variable numbers of large, atypical cells. Using combined immunohistochemistry, the authors compared the expression of a marker of proliferation (DNA topoisomerase IIalpha) between B cells, T cells, and histiocytes. Sixteen cases of LYG were stained by combined immunohistochemistry for DNA topoisomerase IIalpha and CD-20, CD-3, CD-68, and CD-57. A proliferation index was determined for B cells, T cells, histiocytes, and natural killer cells by dividing the number of cells with coexpression of DNA topoisomerase IIalpha and CD-20, CD-3, CD-68, or CD-57 by the total number of CD-20+, CD-3+, CD-68+, or CD-57+ cells, respectively. A significantly higher proliferation index was present in B cells compared to T cells, histiocytes, or natural killer cells (p < 0.002). The average proliferation index for B cells was 0.25+/-0.24 (range, 0.00-0.76), for T cells was 0.02+/-0.01 (range, 0.00-0.04), for histiocytes was 0.00+/-0.01 (range, 0-0.02), and for natural killer cells was 0.00+/-0.00 (range, 0.0-0.02). The average proliferation index of CD-20+ cells was greater in grade III LYG (0.36) than in grade II LYG (0.17) or the single case of grade I LYG (0.00). The authors conclude that (1) there is a spectrum of B-cell proliferation in LYG that roughly correlates with histologic grade, (2) T cells, histiocytes, and natural killer cells do not proliferate but are recruited, and (3) the average B-cell proliferation index in grade III LYG is similar to that observed in large cell non-Hodgkin's B-cell lymphomas. These observations provide a possible rationale for the use of chemotherapy for grade III LYG and observation or immunologic adjuvants for LYG with grade I or grade II histology.

Species concepts and malaria parasites: detecting a cryptic species of Plasmodium.

Species of malaria parasite (phylum Apicomplexa: genus Plasmodium) have traditionally been described using the similarity species concept (based primarily on differences in morphological or life-history characteristics). The biological species concept (reproductive isolation) and phylogenetic species concept (based on monophyly) have not been used before in defining species of Plasmodium. Plasmodium azurophilum, described from Anolis lizards in the eastern Caribbean, is actually a two-species cryptic complex. The parasites were studied from eight islands, from Puerto Rico in the north to Grenada in the south. Morphology of the two species is very similar (differences are indistinguishable to the eye), but one infects only erythrocytes and the other only white blood cells. Molecular data for the cytochrome b gene reveal that the two forms are reproductively isolated; distinct haplotypes are present on each island and are never shared between the erythrocyte-infecting and leucocyte-infecting species. Each forms a monophyletic lineage indicating that they diverged before becoming established in the anoles of the eastern Caribbean. This comparison of the similarity, biological and phylogenetic species concepts for malaria parasites reveals the limited value of using only similarity measures in defining protozoan species.

Expression of DNA toposiomerase I and DNA topoisomerase II-alpha in testicular seminomas.

DNA topoisomerase I (topo I) is the molecular target of the camptothecin group of anticancer drugs. These drugs are S-phase specific and require elevated topo I for tumor cell killing. To determine whether increased topo I expression occurs in testicular seminomas, 20 cases of testicular seminoma were retrieved from the surgical pathology files at the University of Utah Health Sciences Center and stained with an antibody that recognizes topo I in paraffin embedded human tissue sections. Topo I elevation was observed in 30% (6/20) of the seminomas. Because the response to topo I targeted drugs requires cell proliferation, the proliferative index of the seminomas was determined by immunohistochemical staining for DNA topoisomerase II-alpha (topo II-alpha) a new marker of cell proliferation. AU seminomas had easily detectable topo II-alpha. The average topo II-alpha index of the 20 cases was 52.1 +/- 15.3. Seminomas with elevated topo I had an average topo II-alpha proliferative index of 60.8 +/- 17.5 and seminomas with normal topo I expression had a topo II-alpha proliferative index of 48.4 +/- 13.2. This is significantly different at the 0.05% confidence level. Focal expression of CD30 was seen in 60% (12/20) of the neoplasms. None of the cases showed positive staining for CD15 and c-erbB-2. Our results suggest that chemotherapeutic protocols involving topoisomerase targeting drugs might be useful against testicular seminomas.

Myocardial apoptosis in a heterotopic murine heart transplantation model of chronic rejection and graft vasculopathy.

BACKGROUND: Apoptosis has been implicated in myocardial reperfusion injury and in experimental transplantation rejection. One mechanism of apoptosis is through the interaction of the cell-surface Fas receptor on target cells and the Fas ligand that is expressed on cytotoxic T cells. The purpose of this study was to look for evidence of myocardial Fas receptor, Fas ligand, and apoptosis in a murine heterotopic heart transplantation model of chronic rejection/graft vasculopathy. METHODS: Using the nick-end labeling technique, we examined a murine heterotopic heart transplantation model of chronic rejection/graft vasculopathy (strain B10.A to B10.BR) histologically for evidence of DNA fragmentation. MRNA for the Fas receptor, Fas ligand, and beta-actin was detected with reverse transcription-polymerase chain reaction. RESULTS: Hearts harvested after 30 and 60 days showed an intimal index of the allografts (0.5 +/- 0.1) (mean +/- standard error) that was at least five times more than syngeneic grafts and native (nontransplanted) hearts (p < 0.01). In situ nick end-labeling of partially degraded DNA with terminal deoxynucleotydil transferase showed an increase in apoptotic cells in allografts and syngeneic grafts compared with native hearts. Reverse transcription-polymerase chain reaction detected equal myocardial RNA signal intensity of Fas receptor and beta-actin in allografts, syngeneic grafts, and native hearts. In contrast, allografts showed a strong signal for the Fas ligand mRNA, a signal not seen in syngeneic grafts or native hearts. CONCLUSIONS: Apoptosis is occurring in both allografts and syngeneic grafts in this murine model of chronic rejection/graft vasculopathy, although distinct mechanisms may be involved.

T-cell lymphocytosis associated with invasive thymomas.

Peripheral T-cell lymphocytosis and bone marrow infiltration is a rarely associated feature of invasive thymomas. Hypotheses for the origin of the circulating lymphocytes include a spillover of tumor lymphocytes into the circulation, a neoplastic lymphoid proliferation, and a reactive proliferation of peripheral lymphocytes resulting from a thymoma-induced immunoregulatory disorder. The authors describe two cases of peripheral T-cell lymphocytosis associated with invasive thymomas with a predominantly lymphocyte-rich, cortical type histologic appearance. In both cases T cells constituted as much as 99% of the circulating lymphoid cell population, according to flow-cytometric analysis before and after treatment, and expressed a mature phenotype consistent with medullary thymic or peripheral T cells (CD2+, CD3+, CD4+ or CD8+, CD5+, CD7+) with predominant expression of the alpha/beta T-cell receptor heterodimer. Bone marrow biopsy specimens showed nodular and interstitial infiltrates of small T cells. No monoclonal rearrangement of the T-cell receptor beta gene was observed. Both cases had a normal female karyotype. Our findings confirm those of previous studies supporting a reactive origin for the peripheral lymphocytosis. Although an immunoregulatory disorder is probably involved in lymphocyte proliferation in situ, we postulate that peripheral lymphocytosis results from augmented release of the more mature thymoma-associated lymphocytes into the circulation through tumor invasiveness. A thymic origin is supported by the presence of a subset of peripheral T cells with low-intensity CD5 expression.

CD30 antigen expression in florid immunoblastic proliferations. A clinicopathologic study of 14 cases.

Reactive immunoblastic proliferations may be confused with certain types of non-Hodgkin's lymphoma and Hodgkin's disease on morphologic grounds. In addition, a characteristic antigen, CD30 (Ki-1; BerH2) on these neoplastic entities may be observed in morphologically atypical yet reactive florid immunoblastic proliferations such as those associated with acute infectious mononucleosis. Although it has been documented, a large series determining the frequency and extent of CD30 antigen expression on a variety of nonneoplastic immunoblastic proliferations is lacking. The authors studied 14 florid immunoblastic proliferations (9 in lymph nodes and 5 in tonsils) for CD30 antigen expression and for B- and T-cell paraffin markers. In situ hybridization to determine the presence of Epstein-Barr virus (EBV) genomes also was performed. Cases were classified into monospot-positive acute infectious mononucleosis (4 cases), EBV-related lymphoproliferative disorder suggestive of acute infectious mononucleosis (5 cases), and other etiologies (5 cases). CD30 Antigen expression was found on the immunoblasts in cases from all three categories and overall in 9 (64%) of 14 specimens. CD30 reactivity in the positive cases varied from occasional to numerous positive cells; 4 samples (3 EBV-related lymphoid proliferations and 1 vaccine-related lymphadenopathy) had numerous CD30-reactive immunoblasts. Expression of CD30 antigen on B or T cells and prominence of B or T cells within a proliferation were variable. Significant "atypia" of immunoblasts was found only in EBV-related disorders and correlated with B-cell prominence of the infiltrate. Appropriate clinical correlation and ancillary laboratory data are necessary to assist in differentiating these CD30(+)-reactive disorders from similar-appearing malignant lymphomas. Most important, a fresh tissue sample should be procured and adequately processed to allow for comprehensive determination of clonality and cellular lineage.