Increased endothelial activation in recently symptomatic versus asymptomatic carotid artery stenosis and in cerebral microembolic-signal-negative patient subgroups.

BACKGROUND AND PURPOSE: von Willebrand factor propeptide (VWF:Ag II) is potentially a more sensitive marker of acute endothelial activation than von Willebrand factor antigen (VWF:Ag). These biomarkers have not been simultaneously assessed in asymptomatic versus symptomatic carotid stenosis patients. The relationship between endothelial activation and cerebral microembolic signals (MESs) detected on transcranial Doppler ultrasound is unknown. METHODS: In this multicentre observational analytical study, plasma VWF:Ag and VWF:Ag II levels in patients with ≥50% asymptomatic carotid stenosis were compared with those from patients with ≥50% symptomatic carotid stenosis in the 'early' (≤4 weeks) and 'late' (≥3 months) phases after transient ischaemic attack or ischaemic stroke. Endothelial activation was also longitudinally assessed in symptomatic patients during follow-up. Transcranial Doppler ultrasound monitoring classified patients as MES-positive or MES-negative. RESULTS: Data from 31 asymptomatic patients were compared with those from 46 early symptomatic and 35 late phase symptomatic carotid stenosis patients, 23 of whom had undergone carotid intervention. VWF:Ag II levels were higher in early (12.8 µg/ml; P < 0.001), late (10.6 µg/ml; P = 0.01) and late post-intervention (10.6 µg/ml; P = 0.038) symptomatic patients than asymptomatic patients (8.9 µg/ml). VWF:Ag levels decreased in symptomatic patients followed up from the early to late phase after symptom onset (P = 0.048). Early symptomatic MES-negative patients had higher VWF: Ag II levels (13.3 vs. 9.0 µg/ml; P < 0.001) than asymptomatic MES-negative patients. CONCLUSIONS: Endothelial activation is enhanced in symptomatic versus asymptomatic carotid stenosis patients, in early symptomatic versus asymptomatic MES-negative patients, and decreases over time in symptomatic patients. VWF:Ag II levels are a more sensitive marker of endothelial activation than VWF:Ag levels in carotid stenosis. The potential value of endothelial biomarkers and concurrent cerebral MES detection at predicting stroke risk in carotid stenosis warrants further study.

Immune interaction between respiratory syncytial virus infection and allergen sensitization critically depends on timing of challenges.

Severe respiratory syncytial virus (RSV) infection has been hypothesized to be a risk factor for the development of allergy and asthma, but epidemiologic studies in humans have been inconclusive. By use of a well-characterized murine model of RSV infection and allergic sensitization with ovalbumin, the effect of a preceding severe RSV infection on the development of the pulmonary allergic inflammatory response and airway hyperresponsiveness (AHR) was tested. The impact of prior allergic sensitization on RSV-induced illness, as measured by weight loss, also was evaluated. RSV infection before allergic sensitization decreased allergen-induced AHR, production of interleukin-13 in lung tissue, and lung eosinophilia. In contrast, allergic sensitization before RSV infection increased AHR and decreased RSV-related weight loss and lung levels of interferon-gamma but did not alter viral clearance. These data provide evidence that RSV-associated AHR occurs in hosts with allergic responses and that allergic inflammation is diminished when preceded by RSV infection.

Respiratory syncytial virus infection does not increase allergen-induced type 2 cytokine production, yet increases airway hyperresponsiveness in mice.

Severe respiratory syncytial virus (RSV)-induced disease is associated with childhood asthma and atopy. We combined murine models of allergen-sensitization and RSV infection to explore the interaction of allergic and virus-induced airway inflammation and its impact on airway hyperresponsiveness (AHR). We found that RSV infection during ova-sensitization (OVA/RSV) increased and prolonged AHR compared to mice only RSV-infected (RSV) or ova-sensitized (OVA). AHR is known to be associated with an increase in Type 2 cytokines (IL-4, IL-5, and IL-13) in allergen-sensitized mice. Therefore, we hypothesized that RSV-induced enhancement of AHR was a result of potentiating the Type 2 cytokine profile promoted by ova-sensitization. Surprisingly, we found that Type 2 cytokines induced by ova-sensitization were not increased by RSV infection despite the increase in AHR, and in some cases were diminished. RNAse protection assay revealed no difference in IL-4 and IL-5 mRNA levels between the OVA and OVA/RSV groups, and IL-13 mRNA was significantly decreased in the OVA/RSV mice compared to the OVA group. Flow cytometric analysis of Type 2 cytokines demonstrated the same frequency of IL-4 and IL-5 production in lung-derived T lymphocytes from the OVA/RSV and OVA groups. Direct cytokine ELISA measurements of lung supernatant showed the level of IL-13 was significantly decreased in the OVA/RSV group compared to OVA mice, while there was no difference in either IL-4 or IL-5 between these two groups. These data indicate that the enhanced and prolonged AHR caused by the interaction of allergic airway inflammation and virus-induced immune responses is a complex process that can not be explained simply by augmented production of Type 2 cytokines.

Genetic variance of sexually selected traits in waxmoths: maintenance by genotype x environment interaction.

When traits experience directional selection, such as that imposed by sexual selection, their genetic variance is expected to diminish. Nonetheless, theory and findings from sexual selection predict and demonstrate that male traits favored by female choice retain substantial amounts of additive genetic variance. We explored this dilemma through an ecological genetic approach and focused on the potential contributions of genotype x environment interaction (GEI) to maintenance of additive genetic variance for male signal characters in the lesser waxmoth, Achroia grisella (Lepidoptera: Pyralidae). We artificially selected genetic variants for two male signal characters, signal rate (SR) and peak amplitude (PA), that influence female attraction and then examined the phenotypic plasticity of these variants (high- and low-SR and high- and low-PA lines) under a range of environmental conditions expected in natural populations. Our split-family breeding experiments indicated that two signal characters, SR and PA, and several developmental characters in both high- and low-SR and high- and low-PA lines displayed considerable phenotypic plasticity among the environments tested. Moreover, strong GEIs leading to crossover between high- and low-SR lines were found for SR and developmental period. Therefore, neither high- nor low-SR genetic variants would achieve maximum attractiveness and fitness in every environment, and those variants producing unattractive signals with low SRs under normal conditions may remain in populations provided that gene flow across environments or generation overlap are sufficiently high. We speculate that the phenotypic plasticity for SR and developmental period is adaptive in A. grisella populations experiencing a range of temperature and density conditions. Females mating with attractive (high-SR) males may be assured of obtaining good genes because these males sire offspring that develop more rapidly and a crossover for developmental period may parallel that for SR. Such parallel crossovers may be expected wherever good-genes sexual selection mechanisms operate.

Respiratory syncytial virus (RSV)-induced airway hyperresponsiveness in allergically sensitized mice is inhibited by live RSV and exacerbated by formalin-inactivated RSV.

Respiratory syncytial virus (RSV)-induced disease is associated with recurrent episodes of wheezing in children, and an effective vaccine currently is not available. The use of 2 immunizations (a formalin-inactivated, alum-precipitated RSV vaccine [FI-RSV] given intramuscularly and live RSV given intranasally [LVIN]), with a control immunization, were compared in a well-characterized model of RSV challenge, with or without concomitant allergic sensitization with ovalbumin. FI-RSV caused a significant increase in airway hyperresponsiveness in mice after RSV infection during allergic sensitization, and this was associated with an increase in type 2 cytokine production. In contrast, immunization with LVIN did not change type 2 cytokine production and protected against RSV-induced airway hyperresponsiveness in the setting of allergic sensitization. This study suggests that immune modulation with RSV vaccination can have profound effects on RSV-induced airway disease and that prevention of airway hyperresponsiveness is an important end point in vaccine development.

Cyclooxygenase inhibition increases interleukin 5 and interleukin 13 production and airway hyperresponsiveness in allergic mice.

The immunomodulatory role of arachidonic acid metabolites in allergic sensitization is undefined. Prostaglandin E(2) (PGE(2)), a product of arachidonic acid metabolism through the cyclooxygenase pathway, has been reported to favor Type 2-like cytokine secretion profiles in murine and human CD4(+) T cells by inhibiting the production of Type 1-associated cytokines. On the basis of these in vitro data, we hypothesized that indomethacin, a nonselective cyclooxygenase inhibitor, would diminish allergen-induced production of Type 2 cytokines in mice, and protect against airway hyperresponsiveness (AHR) to methacholine. We found that ovalbumin-sensitized mice that were treated with indomethacin (OVA-indomethacin mice) had significantly greater AHR (p < 0.05) and higher levels of IL-5 (176 +/- 52 versus 66 +/- 4 pg/ml) and IL-13 (1,226 +/- 279 versus 475 +/- 65 pg/ml) in lung supernatants than mice sensitized with ovalbumin alone (OVA mice), while levels of IL-4 and serum IgE were not different. Lung mRNA expression of the C-C chemokine MCP-1 was increased in OVA-indomethacin mice, while there was no difference between the two groups in lung mRNA expression of eotaxin, MIP-1alpha, MIP-1beta, or MIP-2. Histologic examination revealed greater pulmonary interstitial eosinophilia in OVA-indomethacin mice as well. Contrary to our expectations, we conclude that in the BALB/c mouse, cyclooxygenase inhibition during allergen sensitization increases AHR, production of IL-5 and IL-13, and interstitial eosinophilia.

Peptide-directed suppression of a pro-inflammatory cytokine response.

Signal-dependent nuclear translocation of transcription factor nuclear factor kappaB (NF-kappaB) is required for the activation of downstream target genes encoding the mediators of immune and inflammatory responses. To inhibit this inducible signaling to the nucleus, we designed a cyclic peptide (cSN50) containing a cell-permeable motif and a cyclized form of the nuclear localization sequence for the p50-NF-kappaB1 subunit of NF-kappaB. When delivered into cultured macrophages treated with the pro-inflammatory agonist lipopolysaccharide, cSN50 was a more efficient inhibitor of NF-kappaB nuclear import than its linear analog. When delivered into mice challenged with lipopolysaccharide, cSN50 potently blocked the production of proinflammatory cytokines (tumor necrosis factor alpha and interferon gamma) and significantly reduced the lethality associated with ensuing endotoxic shock. Based on specificity studies conducted with a mutated form of cSN50, a functional nuclear localization motif is required for this protective effect. Taken together, our findings demonstrate effective targeting of a cell-permeable peptide that attenuates cytokine signaling in vivo. This new class of biological response modifiers may be applicable to the control of systemic inflammatory reactions.

Somatic mutation analysis of IgH variable regions reveals that tumor cells of most parafollicular (monocytoid) B-cell lymphoma, splenic marginal zone B-cell lymphoma, and some hairy cell leukemia are composed of memory B lymphocytes.

The cell of origin of parafollicular (monocytoid) B cell lymphoma (PBCL), splenic marginal zone lymphoma (SMZL), and hairy cell leukemia (HCL) is controversial. To better understand the relationship between these low-grade B-cell neoplasms, we analyzed the nucleotide sequences of the rearranged immunoglobulin heavy (IgH) chain variable (V) region of the clonal population of cells in five cases of PBCL, four cases of SMZL, and seven cases of HCL to determine whether these neoplasms could be differentiated by the degree of somatic mutation in the IgH V gene or by the IgH V gene family usage. DNA was extracted from diagnostic material and clonality confirmed by PCR. The DNA was reamplified using V heavy chain family specific primers, and the amplicons were sequenced. Sequences were compared with germline IgH V gene sequences, and base changes were determined to be silent or to represent amino acid replacements by using three different methods. Four of five (80%) cases of PBCL, three of four (75%) cases of SMZL, and three of seven (43%) cases of HCL showed evidence of antigen selection, suggesting that these neoplasms involved clonal expansions of postgerminal center memory lymphocytes. Only SMZL showed a preferential usage of V(H)1 family genes.

Transformation of the small cell variant Ki-1+ lymphoma to anaplastic large cell lymphoma: pathologic and clinical features.

The disease spectrum of anaplastic large cell lymphoma (ALCL) includes a biologically aggressive small cell variant (SCV). The SCV may progress to ALCL, but little is known about the transformation process and its significance. The goals of this study were (1) to identify the clinical and pathologic features that characterize ALCL arising in SCV and (2) to determine whether some cases with ALCL histologic appearance at the outset arose from an SCV. Seventeen SCV were reviewed, and four cases (24%) transformed to ALCL as shown by subsequent biopsy. The ALCLs were predominantly monomorphic (3 cases) rather than pleomorphic (1 case). Residual SCV was detected at transformation in 3 of 4 cases. Twenty-one de novo T-cell ALCLs were reviewed for an SCV component; such a component was identified in two ALCLs with monomorphic features, suggesting a preceding SCV phase. There was no change in the immunophenotype between the SCV and ALCL, all marking as EMA+ T cells. Expression of p80 was detected in 3 of 4 (75%) SCV with transformation and 10 of 12 (77%) SCV without transformation. Chromosomal abnormalities involving the sex chromosomes and 6, 7, 9, and 15, in addition to the characteristic t(2;5)(p23;q35), were present in 2 cases at transformation. Times to transformation ranged from 1 to 146 months (mean: 63 months) after diagnosis. Transformation to ALCL signaled a rapid clinical course, with 75% of patients dying in less than a year; one patient remains alive at 15 months. In summary, some ALCLs, particularly those with monomorphic features, arise from an SCV. Transformation to ALCL signals a rapid course, with death occurring in less than a year in most cases. Necrosis in the SCV may be predictive of transformation. Chromosomal abnormalities in addition to the t(2;5)(p23;q35) are present at transformation, suggesting that multiple genetic alterations are involved in disease progression.

Quantitative genetics of ultrasonic advertisement signalling in the lesser waxmoth Achroia grisella (Lepidoptera: pyralidae).

Males of the lesser waxmoth Achroia grisella (Lepidoptera: Pyralidae) produce ultrasonic advertisement signals attractive to females within several metres. Previous studies showed that females prefer male signals that are louder, delivered at a faster rate, and have a greater asynchrony between pulses produced by the right and left wings. These three signal characters vary considerably within populations but are repeatable within individuals. Breeding experiments employing half-sib designs were conducted on both collectively and individually reared moths to determine genetic variance within and covariance among these signal characters. Heritabilities of all signal characters were significant among collectively reared moths. Heritabilities for signal rate and right-left wing asynchrony interval were not significant, however, among individually reared moths, suggesting the presence of significant nonadditive genetic variance or common environmental variation. Development time was also significantly heritable, but only under individual rearing. The only significant genetic correlation was between signal rate and length of the right-left wing asynchrony and this was negative. Our findings on heritability of signal characters are consistent with a coevolutionary sexual selection mechanism, but the absence of signal x development genetic correlation fails to support specifically a good-genes mechanism. The variation in heritability among conditions suggests that environmental variance may be high, and may render selection on signal characters by female choice ineffective. Thus, additive genetic variance for these characters may be maintained in the presence of directional female choice.

MOPP or radiation in addition to ABVD in the treatment of pathologically staged advanced Hodgkin's disease in children: results of the Children's Cancer Group Phase III Trial.

PURPOSE: A randomized trial designed to compare mechlorethamine, vincristine, procarbazine, and prednisone (MOPP)/doxorubicin, bleomycin, vinblastine, and daccarbazine (ABVD) (regimen A) with ABVD plus low-dose regional (extended-field) radiation therapy (EF RT) (regimen B) for the treatment of children and adolescents with stages III and IV Hodgkin's disease was conducted by the Children's Cancer Group (CCG-521) from 1986 until 1990. PATIENTS AND METHODS: One hundred eleven eligible patients were randomized, 57 to regimen A and 54 to regimen B. All patients had pathologically verified stage III or stage IV Hodgkin's disease. RESULTS: Overall survival (S) is 87% at 4 years and event-free survival (EFS) is 82%. Patients randomized to ABVD plus EF RT have a 4-year EFS of 87% compared with 77% for patients randomized to MOPP/ABVD (P = .09, two-sided). Patients randomized to ABVD plus EF RT have a 4-year S of 90% compared with 84% for patients randomized to MOPP/ABVD (P = .45, two-sided). Significant prognostic factors in multivariate analysis for EFS are stage of disease, erythrocyte sedimentation rate (ESR) at diagnosis, liver size at diagnosis, and, among stage III patients, the size of the mediastinal mass at diagnosis. The acute toxicities of treatment are largely hematopoietic in nature, whereas acute pulmonary and cardiac toxicities are modest and not limiting. CONCLUSION: The results of this study show that, in advanced-stage Hodgkin's disease in children, equivalent results can be obtained by the addition of either MOPP or low-dose EF RT to the ABVD regimen; whether the addition of either contributes to outcome was not addressed in this study and will require additional testing. It is clear, however, that MOPP chemotherapy can safely be eliminated from front-line combination chemotherapy regimens for advanced Hodgkin's disease in pediatric patients.

Technical aspects of catheter-related interventions in the liver of the rabbit.

PURPOSE: On the basis of 89 different vascular interventions performed in the livers of 39 rabbits, we attempted to establish the feasibility and technical limitations of these procedures. MATERIAL AND METHODS: Forty-five selective hepatic artery catheterizations were carried out using 0.66-mm and 1.0-mm catheters, including superselective proper hepatic catheterizations (n = 14) using a specially designed 0.66-mm introducer/catheter system. The portal system was investigated with both direct (n = 5) and indirect (arterial) (n = 4) portography. Hepatic, vein catheterizations were performed in 22 cases. RESULTS: With the 0.66-mm system, spasm occurred in one of 11 cases in the proper hepatic artery, and no spasm was observed in the common hepatic and celiac arteries. Both arterial portography and hepatic venography were easily performed and were a precise and repeatable method. CONCLUSION: The 0.66-mm system has proved to be advantageous over the 1.0-mm catheterization in avoiding arterial spasm. Direct portography as well as catheterization of the hepatic vein from a jugular approach are hazardous, leading to serious complications including the death of the animal.

Recurrent Hodgkin's disease after bone marrow transplantation.

Histologic features of recurrent Hodgkin's disease (HD) after conventional therapy are well known, but few studies describe HD after bone marrow transplantation (BMT). Histologic material from 63 patients who underwent BMT performed to treat recurrent nodular sclerosing HD (NSHD) between 1985 and 1994 was examined; 13 of the 63 patients had histologically proved recurrent disease after BMT. Histologic material and clinical findings from the original diagnostic biopsy specimen and pre-BMT and post-BMT specimens were available from our study population of eight patients (five male, three female; age range, 16 to 38 years; median age, 27.5 years). Seven patients had recurrent NSHD after BMT; sites of recurrence included lymph nodes only (four patients), and lymph nodes and lung, lung and liver, and lung only (one patient each). In one patient, a high-grade non-Hodgkin's B-cell lymphoma developed in the large intestine 5 years after BMT. In another, disease progressed from grade 1 in the original biopsy specimen to grade 2 in both the pre-BMT and post-BMT recurrent HD biopsy specimens. Post-BMT biopsy specimens of recurrent HD with lung involvement revealed a substantial increase in sclerosis and fibroblastic features. Paraffin immunoperoxidase studies in seven patients demonstrated substantial change in phenotype of Reed-Stemberg cell variants in only one post-BMT recurrent HD specimen, which showed a +2 reaction with CD30 (Ki-1). No substantial differences in the reactive component were noted between the original biopsy specimen and pre-BMT and post-BMT specimens of recurrent disease. In summary, histologic findings of post-BMT recurrent NSHD do not differ significantly from those of the original diagnostic biopsy or pre-BMT recurrent HD specimens. The lung is the most common site of extranodal post-BMT recurrence. In one patient, high-grade non-Hodgkin's B-cell lymphoma developed after BMT performed to treat recurrent HD.

The spectrum of multiple myeloma: diagnostic and biological implications.

Myeloma is a common and well-studied hematopoietic neoplasm with an impressive spectrum of clinical, laboratory, and histological findings. To enhance our understanding of the diversity of myeloma, including its earliest forms, the clinical and pathological findings in 145 cases of myeloma were documented and analyzed. Our analysis indicated that myeloma has at least two distinct subtypes: one presenting with bone lesions and a nodular growth pattern and the other presenting with anemia and an infiltrative growth pattern. The relationship of these two forms to plasma cell biology is not clear, although both types appear to arise in the marrow. The criteria used in this study identified 85% of cases overall, with a range of 70% to 100%, depending on clinical presentation. Immunoperoxidase studies are required to establish the diagnosis in patients with early marrow involvement. Myeloma in younger patients appears to be clinically and pathologically similar to myeloma in older patients. Factors such as dysplasia, immunoglobulin type, or leukemic phase were evenly distributed among clinical presentations and did not apparently identify clinicopathological subtypes of myeloma.

Cat scratch disease: detection of Bartonella henselae DNA in archival biopsies from patients with clinically, serologically, and histologically defined disease.

Serological and epidemiological studies suggest that Bartonella henselae is the etiological agent of cat scratch disease. We designed a study to detect B. henselae in archival biopsies by polymerase chain reaction amplification of the 16S rRNA gene followed by Southern blot hybridization. Forty-two histologically defined cat scratch disease biopsies and eighteen controls were selected for blinded analysis. After testing, charts were reviewed for clinical, immunological, and microbial evidence of infection. Results were correlated with duration of illness and antimicrobial therapy. B. henselae DNA was identified in 27 of 42 (64%) histologically defined patients and 23 of 34 (68%) patients defined both clinically and histologically. There were no false positives (0 of 18). A small subset (n = 14) had cat scratch disease serological tests performed. B. henselae was identified in 8 of 10 serologically positive patients. Polymerase chain reaction detected 50% of our DNA-positive cases (most of these early in the clinical course). Southern blotting of amplicons both doubled sensitivity (detecting patients > 4 weeks into illness) and confirmed B. henselae as the causative species. Our study strongly associates B. henselae with cat scratch disease, suggesting that it may be the most likely etiological agent in the majority of patients with cat scratch disease.

HIV protease inhibitory bis-benzamide cyclic ureas: a quantitative structure-activity relationship analysis.

A series of N,N'-disubstituted cyclic urea 3-benzamides has been synthesized and evaluated for HIV protease inhibition and antiviral activity. Some of these benzamides have been shown to be potent inhibitors of HIV protease with Ki < 0.050 nM and IC90 < 20 nM for viral replication and, as such, may be useful in the treatment of AIDS. The synthesis and quantitative structure-activity relationship for this benzamide series will be discussed.

Splenic marginal zone lymphoma. A distinct B-cell neoplasm.

The splenic marginal zone is a morphologically and perhaps immunologically distinct B-cell compartment. Lymphomas arising from cells of the splenic marginal zone are rare. Here we describe the morphologic, immunologic, and clinical features of 14 cases. Patient age ranged from 35 to 79 years (median, 68 years) with a male-to-female ratio of 1:1.8. The spleen was uniformly enlarged (median, 1,540 g; range, 388-3,845 g) in all patients, the neoplastic infiltrate had a nodular pattern in three cases, nodular and diffuse in seven cases, and diffuse in four cases. The neoplastic cells had small to medium-sized nuclei with round, oval, or slightly indented contours, small eosinophilic nucleoli, and a moderate amount of pale cytoplasm. Extrasplenic involvement was present in 12 patients. Lymph nodes often had a vaguely nodular pattern and preservation of sinuses; bone marrow was infiltrated focally (seven cases) or diffusely (one case). Five patients had hepatic involvement. Ultrastructurally, neoplastic cells differed from other small B cells and resembled normal marginal zone cells by having long, serpentine rough endoplasmic reticulum profiles. All lymphomas marked as B cells and light chain restriction was demonstrated in 12 cases. Bcl-2 protein expression was present in all cases. Most cases (70%) were negative for DBA.44 (CD72). Plasmacytic differentiation was present in three cases. In conclusion, splenic marginal zone lymphoma is a B-cell neoplasm with distinctive clinical, morphologic, immunologic, and ultrastructural characteristics.

Natural killer-like T-cell lymphomas: aggressive lymphomas of T-large granular lymphocytes.

Natural killer (NK)-like T cells are major histocompatibility complex-unrestricted cytotoxic T cells that are surface CD3-positive, express NK-cell antigens, and rearrange their T-cell receptor. Most neoplasms arising from this T-cell subpopulation have been a chronic lymphoproliferative disease referred to as T-large granular lymphocyte (LGL) leukemia. Only 10 NK-like T-cell lymphomas have been described in detail previously; this study presents the clinicopathologic features of six others and distinguishes these lymphomas from T-LGL leukemia. All patients presented with B-symptoms and often had marked hepatosplenomegaly without significant peripheral lymphadenopathy. Four of the six patients were immunosuppressed. All had CD3, CD8, CD56-positive tumors, presumably of hepatosplenic (n = 3), intestinal (n = 1), pulmonary (n = 1), or nodal (n = 1) origin. Three patients had lymphomatous bone marrow infiltrates, and four had peripheral blood involvement by neoplastic large lymphocytes, some of which had a blastic appearance or resembled virocytes. Azurophilic granules, ultrastructurally corresponding to cytoplasmic dense core and/or double density granules, were seen in all cases. T-cell clonality was shown in five tumors by Southern blot analysis, and three had abnormal karyotypes. Two untreated patients died 20 days after presentation, and three patients who received combination chemotherapy died within 5 months of presentation. One patient remains in complete remission 22 months after treatment. These findings suggest NK-like T-cell lymphomas are aggressive, are clinicopathologically distinct from T-LGL leukemia, and should be in the differential diagnosis of extranodal T-cell lymphoproliferations, including those in immunosuppressed patients. Furthermore, the LGL morphology, phenotype, and tissue distribution of some NK-like T-cell lymphomas suggest they arise from thymic-independent T cells of the hepatic sinusoids and intestinal mucosa.