Planned Neck Dissection after Definitive Radiotherapy or Chemoradiation for Base of Tongue Cancers

OBJECTIVES: The study goal was to analyze the role of planned neck dissection for squamous cell carcinoma of the base of the tongue treated with definitive radiotherapy or chemoradiation.

STUDY DESIGN, SETTING: We conducted a retrospective study of patients with squamous cell carcinoma of the base of the tongue undergoing planned neck dissection after definitive radiotherapy or chemoradiation.

RESULTS: Twenty-two of 41 (53.7%) patients had one to six positive residual lymph nodes after receiving definitive radiotherapy or chemoradiation. Neck control rates were 92.3% and 88.3% at two and five years, respectively. Three of 22 (13.6%) patients with pathological residual nodal disease had regional or locore-gional failures, compared with 1 of 19 (5.3%) patients with a pathologically complete response ( P = 0.39).

CONCLUSIONS: We observed a high incidence of pathologically residual lymph nodes after definitive radiotherapy or chemoradiation.

SIGNIFICANCE: Planned neck dissection following definitive radiotherapy or chemoradiation is highly effective in achieving regional control of squamous cell carcinoma of the base of the tongue.

Hereditary Head and Neck Paragangliomas

Objective: Paragangliomas are rare neuroendocrine tumors derived from the extra-adrenal paraganglia of the autonomic nervous system. Little information has been accumulated describing the differences in clinical expression between hereditary versus nonhereditary paraganglia. We examined the differences in clinical characteristics, presenting symptoms, and tumor types of hereditary head and neck paragangliomas.

Method: A retrospective review of the medical records was performed in order to formulate a database of patients with head and neck paragangliomas. Clinical characteristics, tumor type and location, presentation, and genetic results of each patient were included. Hereditary paragangliomas were compared to the general database of head and neck paragangliomas.

Results: Eighty patients with the diagnosis of a head and neck paraganglioma were evaluated at the University of Utah during the years of 2000 to 2010. Thirteen of the 80 were confirmed to be hereditary paragangliomas through genetic testing or through family history. Patients with a known hereditary component presented earlier in life than those of the general paraganglioma population. Over half of the patients who presented under the age of 30 years were confirmed to be hereditary. The most common presenting symptom was a neck mass (54%). A genetic mutation was found in all those tested under the age of 30 years.

Conclusion: Our study evaluates a large population of hereditary paragangliomas. We found that patients who present at a younger age may be at an increased risk of possessing a genetic mutation. Further research will determine if genetic testing is necessary in all patients who present under the age of 30 years.

Abstract 4388: beta-Carotene's oxidative breakdown inhibits p53 conformational folding and function

Lipophilic electrophiles have been found to have the ability to inhibit wild-type p53 protein function through a thioredoxin-dependent inhibition of functional protein folding. One potential extension of this line of research may help to explain the curious findings of certain carotenoid-based chemopreventive clinical trials that found that beta-carotene may be a contributory causal risk of cancer development in patients who actively smoke. Chemical precepts dictate that wild-type p53 function may be inihibited through a similar mechanism by other other lipophilic compounds such as carotenoids within a high redox milieu of ongoing smoking. We ask the question whether the oxidative breakdown of beta-carotene could inhibit p53 function via a similar post-translational mechanism. Using resonance Raman spectroscopy, HPLC, spectrophotometry, and Western blot analysis, we exposed isolated cell-free and intracellular beta-carotene to various oxidant sources such as nitric oxide (NO·), superoxide (O·), and/or the combination of NO· and O· [i.e. SNAP (NO+ donor), Spermine-NONOate (NO. donor), and SIN-1 (NO·/O· donor), and Angeli's salt (an NO[[Unsupported Character - Codename ­]]- donor)] as a model of ongoing oxidative stress. Our results demonstrate that the oxidative breakdown of beta-carotene specifically by SIN-1 (the donor of NO·/O· causes stabilization of p53, attributable to the accumulation of both “functional” and “non-functional” conformational folding. Finally, we demonstrate that the oxidative breakdown products of beta-carotene can inhibit thioredoxin function, thus providing a biochemical mechanism for the inhibition of wild-type protein folding. Taken together, these data support the hypothesis that ongoing oxidation of beta-carotene can inhibit this key cancer-related molecular pathway, through the post-translational inhibition p53 folding and function. These data may provide one biochemical mechanism for the surprising results of initial carotenoid-based chemopreventive cancer trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4388.

SDH5, a gene required for flavination of succinate dehydrogenase, is mutated in paraganglioma

Mammalian mitochondria contain about 1100 proteins, nearly 300 of which are uncharacterized. Given the well-established role of mitochondrial defects in human disease, functional characterization of these proteins may shed new light on disease mechanisms. Starting with yeast as a model system, we investigated an uncharacterized but highly conserved mitochondrial protein (named here Sdh5). Both yeast and human Sdh5 interact with the catalytic subunit of the succinate dehydrogenase (SDH) complex, a component of both the electron transport chain and the tricarboxylic acid cycle. Sdh5 is required for SDH-dependent respiration and for Sdh1 flavination (incorporation of the flavin adenine dinucleotide cofactor). Germline loss-of-function mutations in the human SDH5 gene, located on chromosome 11q13.1, segregate with disease in a family with hereditary paraganglioma, a neuroendocrine tumor previously linked to mutations in genes encoding SDH subunits. Thus, a mitochondrial proteomics analysis in yeast has led to the discovery of a human tumor susceptibility gene.

Fine Needle Aspiration Analysis of B-RAF in Thyroid Nodules

Objective

Fine needle aspiration (FNA) represents the most useful initial diagnostic tool with which to analyze thyroid nodules for carcinoma. A mutation of the B-type RAF kinase (BRAF) represents the most common genetic alteration in sporadic papillary thyroid cancer (PTC), and may signify a more aggressive biological behavior within PTCs. Our objective was to determine if BRAF analysis of FNA cytology may provide clinically useful information in the analysis of thyroid nodules.

Methods

An IRB-approved retrospective chart review of clinically relevant data for classic PTCs (CPTC), follicular-variant of PTC (FV-PTC), or non-malignant goiter was performed following a blinded pathologic re-review. Both pathologic and cytology samples were analyzed by fluorescent melting curve analysis (FMCA) for the V600E mutation of BRAF, and mutational status was compared with clinical information.

Results

A 100% concordance was found for BRAF mutation determination between the cytologic and final pathologic malignant and benign tissue samples studied. BRAF mutation was found to be significantly higher in papillary carcinomas when compared to follicular-variant of papillary thyroid carcinomas (55.6% vs. 14.3%, p=0.05), and correlated with cytologic interpretation (p=0.025) and histologic diagnosis (p=0.03).

Conclusions

FMCA of thyroid nodule FNAs can accurately determine the mutational status of the BRAF gene. Since the presence of BRAF mutation can predict a more aggressive biological behavior, an analysis of BRAF mutational status of initial FNAs may add useful information to the list of risk stratification criteria for PTCs.

Detection of BRAF V600E activating mutation in papillary thyroid carcinoma using PCR with allele-specific fluorescent probe melting curve analysis

BACKGROUND

A single hotspot mutation at nucleotide 1799 of the BRAF gene has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence of 29-83%.

AIMS

To use a PCR assay to molecularly characterise the BRAF activating point mutation in a series of PTC and benign thyroid cases and correlate the mutation results with histological findings.

METHODS

Formalin-fixed paraffin-embedded (FFPE) sections were evaluated for the BRAF V600E mutation using LightCycler PCR with allele-specific fluorescent probe melting curve analysis (LCPCR).

RESULTS

42 (37 PTC; 5 benign) surgical tissue samples were analysed for the BRAF V600E activating point mutation. Using LCPCR and direct DNA sequencing, the BRAF mutation was identified in 23/37 (62.2%) PTC FFPE samples. DNA sequencing results demonstrated confirmation of the mutation.

CONCLUSIONS

Detection of BRAF-activating mutations in PTC suggests new approaches to management and treatment of this disease that may prove worthwhile. Identification of the BRAF V600E activating mutation in routine FFPE pathology samples by a rapid laboratory method such as LCPCR could have significant value.

Parosteal osteosarcoma: Case report and review of the literature

BACKGROUND

The majority of osteosarcoma cases of the head and neck are high-grade lesions. We present a case and discuss the diagnostic and therapeutic implications of a rare low-grade parosteal osteosarcoma of the maxilla.

METHODS

A 32-year-old man presenting to the Head and Neck Surgical Oncology clinic with a 1-year history of a firm palatal mass. Evaluation clinically and radiographically raised the suspicion of an osteosarcoma.

RESULTS

A partial maxillectomy revealed a parosteal osteosarcoma with negative margins. No adjuvant therapy was recommended, and the patient remains without evidence of local recurrence after 3 years.

CONCLUSIONS

Parosteal osteosarcomas of the head and neck region are rare, low-grade variants of osteosarcoma, but have the potential to recur with simple local excision. Clinical and radiographic features are diagnostically helpful. Definitive diagnosis comes from histopathology, and wide local resection should be employed as the optimal treatment.

Treatment of oropharyngeal squamous cell carcinoma with external beam radiation combined with interstitial brachytherapy

BACKGROUND

We reviewed the outcomes of oropharyngeal squamous cell carcinoma treated with external beam radiation and interstitial brachytherapy.

METHODS

Ninety patients with squamous cell carcinoma of the oropharynx were treated with interstitial brachytherapy at the University of Utah between 1984 and 2001. Seventy-two patients received external beam radiotherapy (EBRT) followed by brachytherapy boost, 11 had surgery followed by EBRT and brachytherapy, 4 had surgery and brachytherapy, and 3 were treated with brachytherapy alone. Median doses for EBRT and brachytherapy were 50 and 24 Gy, respectively.

RESULTS

Median follow-up after brachytherapy was 48.3 months for all patients. Five-year local control, disease-free survival, and overall survival were 76%, 61%, and 55%. For T1, T2, T3, and T4, 5-year local control rates were 83%, 79%, 79%, and 64%, respectively. Severe complications occurred in 13 patients, including 2 treatment-related deaths.

CONCLUSIONS

EBRT combined with interstitial brachytherapy provide good local control rates for locally advanced oropharyngeal squamous cell carcinoma.

Utility of BRAF V600E mutation detection in cytologically indeterminate thyroid nodules

Background

Fine needle aspiration (FNA) is widely utilized for evaluation of patients with thyroid nodules. However, approximately 30% are indeterminate for malignancy. Recently, a mutation in the BRAF gene has been reported to be the most common genetic event in papillary thyroid carcinoma (PTC). In this retrospective study, we assessed the utility of BRAF V600E mutation detection for refining indeterminate preoperative cytologic diagnoses in patients with PTC.

Methods

Archival indeterminate thyroid FNAs and corresponding formalin-fixed, paraffin-embedded (FFPE) surgical samples with PTC were identified in our patient files. DNA extracted from slide scape lysates and 5 μm FFPE sections were evaluated for the BRAF V600E mutation using LightCycler PCR and fluorescent melting curve analysis (LCPCR). Amplification products that showed deviation from the wild-type genomic DNA melting peak, discordant FNA and FFPE matched pairs, and all benign control samples, underwent direct DNA sequencing.

Results

A total of 19 indeterminate thyroid FNAs demonstrating PTC on FFPE surgical samples were included in the study. Using BRAF mutation analysis, the preoperative diagnosis of PTC was confirmed in 3/19 (15.8%) FNA samples that could not be conclusively diagnosed on cytology alone. However, 9/19 (47.4%) FFPE tissue samples were positive for the V600E mutation. Of the discordant pairs, 5/6 FNAs contained less than 50% tumor cells.

Conclusion

When used with indeterminate FNA samples, BRAF mutation analysis may be a useful adjunct technique for confirming the diagnosis of malignancy in an otherwise equivocal case. However, overall tumor cell content of some archival FNA smear slides is a limiting factor for mutation detection.

Black thyroid resulting from short-term doxycycline use: Case report, review of the literature, and discussion of implications

BACKGROUND

Black thyroid pigmentation has been considered pathognomonic for chronic minocycline ingestion for more than 30 years. Although never conclusively linked to overt disease, evidence clearly exists that minocycline is a competitive inhibitor of thyroid peroxidase in metabolically active thyroid tissue. This offers a potential mechanism of pigment accumulation, which can account for the occasional finding of hypopigmentation in thyroid carcinomas. To our knowledge, an association with tetracycline derivatives other than minocycline has not been documented.

METHODS

Herein is a case report of a patient with gross black thyroid tissue containing a hypopigmented papillary thyroid carcinoma. Twelve days before surgery, the patient was placed on doxycycline, a tetracycline derivative, to optimize an in vitro fertilization regimen.

RESULTS

The gross specimen was diffusely black in color with a 1.5-cm hypopigmented focus of papillary thyroid cancer. Hematoxylin-eosin staining, as well as electron micrographs, was consistent with findings associated with minocycline ingestion.

CONCLUSIONS

Black thyroid is rare and only previously associated with chronic minocycline ingestion. This report documents a black thyroid in a patient after short-term exposure to doxycycline. Pigment accumulation in normal tissue is thought to occur by inhibition of thyroid peroxidase. Minocycline is a competitive inhibitor of this enzyme in its native configuration. Thyroid carcinomas are known to have abnormal thyroid peroxidase, which could account for reports of hypopigmented tumors within grossly darkened thyroid tissue. Hypopigmented foci within such "black thyroid" deserve through pathologic examination.

The Magnanimous Professional Life and Tragic Demise of J. H. Douglas, MD

OBJECTIVES/HYPOTHESIS

Many of the hallmarks of a very successful medical career, such as recognition as a leader in a field of medicine, making important contributions to medical knowledge of the day, and a steadfast dedication to patient care, had already been achieved by Dr. John Hancock Douglas. Therefore, the mystery surrounding his dismissal from membership of the newly formed American Laryngology Society (now the ALA) and his tragic demise stand in stark contrast. We discuss the model professional life and mysterious but tragic final days of this very important laryngologist of the 19th century.

STUDY DESIGN/METHODS

A historical vignette.

RESULTS

Dr. Douglas's professional qualities of leadership of the American Sanitary Commission, his various contributions to the advancement of medical knowledge during that era, and his steadfast dedication to the care of his patients represent highlights of a very honorable professional career. His final demise, bankrupt, in an ill state of health, and stripped of his professional appointment to the ALA, seems an unjust end to the life of this notable and magnanimous laryngologist.

CONCLUSIONS

We offer this historical review of the life and demise of Dr. John H. Douglas as a tribute to this important figure in our profession's history.

Nitrosative stress induces DNA strand breaks but not caspase mediated apoptosis in a lung cancer cell line

Background

Key steps crucial to the process of tumor progression are genomic instability and escape from apoptosis. Nitric oxide and its interrelated reactive intermediates (collectively denoted as NO_X) have been implicated in DNA damage and mutational events leading to cancer development, while also being implicated in the inhibition of apoptosis through S-nitrosation of key apoptotic enzymes. The purpose of this study was to explore the interrelationship between NO_X-mediated DNA strand breaks (DSBs) and apoptosis in cultured tumor cell lines.

Methods

Two well-characterized cell lines were exposed to increasing concentrations of exogenous NO_X via donor compounds. Production of NO_X was quantified by the Greiss reaction and spectrophotometery, and confirmed by nitrotyrosine immunostaining. DSBs were measured by the alkaline single-cell gel electrophoresis assay (the COMET assay), and correlated with cell viability by the MTT assay. Apoptosis was analyzed both by TUNEL staining and Annexin V/propidium iodine FACS. Finally, caspase enzymatic activity was measured using an in-vitro fluorogenic caspase assay.

Results

Increases in DNA strand breaks in our tumor cells, but not in control fibroblasts, correlated with the concentration as well as rate of release of exogenously administered NO_X. This increase in DSBs did not correlate with an increase in cell death or apoptosis in our tumor cell line. Finally, this lack of apoptosis was found to correlate with inhibition of caspase activity upon exposure to thiol- but not NONOate-based NO_X donor compounds.

Conclusions

Genotoxicity appears to be highly interrelated with both the concentration and kinetic delivery of NO_X. Moreover, alterations in cell apoptosis can be seen as a consequence of the explicit mechanisms of NO_X delivery. These findings lend credence to the hypothesis that NO_X may play an important role in tumor progression, and underscores potential pitfalls which should be considered when developing NO_X-based chemotherapeutic agents.

Head and Neck Soft Tissue Sarcomas: A Multivariate Analysis of Outcomes

BACKGROUND

Soft tissue sarcomas of the head and neck region represent a rare group of tumors of which a limited number of published individual- and institution-based experiences exist.

METHODS

We performed an analysis of head and neck sarcoma patients identified from our institution between 1973 and 1999. Exclusion criteria included pediatric rhabdomyosarcomas, sarcomas of the neuromeningeal axis or non-head and neck primary disease sites, and bone sarcomas. All cases underwent pathologic re-review before statistical analysis.

RESULTS

After pathologic review, 111 head and neck sarcoma patients remained (mean age, 47 +/- 20 years). The median duration of follow-up was 51 months; the actuarial 5-year relapse-free, disease-specific, and overall survivals were 55%, 52%, and 44%, respectively. Forty-six percent remained free of recurrence at the most recent follow-up, and the most common site of recurrence was local followed by distant sites. By multivariate analysis, size and grade significantly influenced relapse-free, disease-specific, and overall survivals, whereas margin status additionally influenced relapse-free survival. Subset analysis of the fibrosarcoma/malignant fibrous histiocytoma and desmoid/dermatofibrosarcoma protuberans histologies was undertaken.

CONCLUSIONS

Size >5 cm and high-grade histology are considered poor prognostic indicators. Patients with either of these characteristics should be considered for adjuvant trials.

Anterior skull base surgery for malignant tumors: a multivariate analysis of 27 years of experience

INTRODUCTION

Few studies have examined prognostic factors that have an impact on outcomes in anterior skull base surgery by multivariate analysis.

METHODS

We retrospectively examined our institution's skull base experience from 1973-2000.

RESULTS

During this time, 166 patients underwent an anterior skull base resection for malignancy (median age, 53 years; range, 6-92 years). The 5-year relapse-free and disease-specific survival was 41% and 57% (median follow-up, 53 months). Multivariate analysis found that dural invasion, primary histologic diagnosis, and margin status had a significant impact on relapse-free and disease-specific survival.

CONCLUSIONS

These data indicate that patients with anterior skull base malignancies are treated successfully with skull base surgery. Patients demonstrating adverse prognostic variables such as dural invasion, adverse histologic findings, and/or positive margins should be considered for the addition of adjuvant therapy or innovative therapies as they become available in the future.

Expression of glutathione s-transferase pi in benign mucosa, Barrett's metaplasia, and adenocarcinoma of the esophagus

BACKGROUND

Glutathione s-transferase pi (GSTpi) is an enzyme that provides cellular protection against redox-mediated damage by free radicals, which have been implicated in carcinogenesis.

METHODS

Forty-three consecutive specimens from 19 patients were reviewed to identify samples of squamous mucosa, Barrett's metaplasia, adenocarcinoma, and peritumoral inflammation. Serial sections were stained with an anti-GSTpi polyclonal antibody, and GSTpi expression was quantified for each histologic group.

RESULTS

GSTpi expression was diminished in peritumoral mononuclear inflammatory cells (p <.001) compared with squamous epithelium, Barrett's metaplasia, or adenocarcinoma. Barrett's metaplasia exhibited decreased GSTpi expression compared with squamous mucosa (p =.045). GSTpi expression by >50% of adenocarcinoma cells was associated with an increased risk (2.25x) of disease at last follow-up.

CONCLUSIONS

GSTpi is prominently expressed in esophageal squamous mucosa and adenocarcinoma. Mononuclear cells may be susceptible to oxidative damage secondary to weak GSTpi production. GSTpi may protect the tumor cells themselves from the cytotoxic effects of free radicals. The biochemical role of GSTpi expression in malignant transformation deserves further investigation.

Anxiety, depression, and the content of worries

Worry content as assessed by using a modified Worry Domains Questionnaire (WDQ) was compared among participants diagnosed with a depressive disorder, generalized anxiety disorder (GAD), and both a depressive disorder and GAD. A discriminant function analysis of worry domains yielded two significant functions. The worry domains Lack of Confidence, Aimless Future, Relationships, and Financial Concerns loaded significantly on Function 1, which was termed "Depressive Worries." The worry domain Loss of Control loaded significantly on Function 2, which was termed "Anxious Worries." The three participant groups differed in their pattern of worries in a way that lends support to the content-specificity hypothesis for both depression and anxiety. In addition, multiple regression analysis indicated that WDQ domain scores (in particular the Aimless Future domain) predicted the severity of depressive symptoms even after the variance contributed by anxiety symptoms was removed from the analysis. These findings suggest that the content of a person's worries may be significantly associated with the presence of depression, anxiety, or comorbid depression and anxiety.

Nitric oxide and apoptosis during human head and neck squamous cell carcinoma development

PURPOSE

Apoptosis index (AI), Bcl-2, and Bax have shown prognostic significance in head and neck squamous cell carcinoma (HNSCCa). Other areas of research have implicated nitric oxide (NO) or its various intermediate species in both proapoptotic and antiapoptotic processes. We have previously shown that NO-generating enzymes are significantly increased during the stepwise progression to HNSCCa. The aim of this study was to explore the interrelationship of NO and a known consequence of NO-related oxidative stress, apoptosis, during this step-wise process.

MATERIALS AND METHODS

Formalin fixed-paraffin embedded tissue samples of 10 normal oral mucosa, 15 reactive/dysplastic lesions, and 17 HNSCCa lesions studied previously were subjected to the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP labeling (TUNEL) assay as well as immunohistochemical staining against Bcl-2, Bax, and p53. Patient charts were reviewed and clinical data were compared. The study pathologist (G.K.H) reviewed these slides blinded to patient identifiers or clinical data. The number of immunopositive cell nuclei or staining intensity was graded, noting the pattern of immunostaining. These staining characteristics were compared with the results of immunostaining previously obtained for endothelial constitutive NO synthase (ecNOS) and nitrotyrosine.

RESULTS

Compared with normal oral mucosa, the AI, Bcl-2, Bax, Bcl-2/Bax intensity and frequency ratios, and mutant p53 intensity significantly changed in reactive/dysplastic and HNSCCa lesions (P <.001 for all). Correlations between the staining characteristics of the antigens studied are presented. Furthermore, perilesional inflammatory cells showed staining in the TUNEL assay.

CONCLUSIONS

In a set of tissue samples previously well characterized, these new findings implicate a link between NO and the induction of apoptotic cell death in HNSCCa development.

Psychometric properties and factor structure of the Worry Domains Questionnaire

The Worry Domains Questionnaire (WDQ) is a content-based measure of nonpathological worry. The current study investigates an adapted WDQ for clinical assessment. The WDQ was completed by 570 participants (286 clinical, 284 nonclinical). Internal consistency of the WDQ domains was found to be adequate. Clinical participants obtained significantly higher WDQ scores than control participants. WDQ scores were moderately correlated with several clinical self-report measures. A seven-factor structure and a higher order worry factor model were separately subjected to structural equation modeling in the clinical sample. The factor groupings originally outlined by the scale's authors (with minor revisions) provided the best description of the clinical data set. Evidence of differences in the worry factor structures of clinical and control samples did emerge. This study provides initial support of the psychometric suitability of the adapted WDQ for use in clinical populations.

Expression of nitric oxide synthase type 3 in reflux-induced esophageal lesions

BACKGROUND

The expression of endothelial constitutive nitric oxide synthase (NOS3) by squamous dysplasia and carcinomas of the head and neck has previously been described. We sought to compare NOS3 expression in squamous mucosa, glandular metaplasia, and adenocarcinoma of the esophagus.

METHODS

Forty paraffin-embedded specimens from 20 patients with adenocarcinoma were stained with anti-NOS3 monoclonal antibody. The percentage of cells stained and the intensity of staining were determined for squamous epithelium, metaplasia, and adenocarcinoma. Staining characteristics were statistically analyzed according to clinical variables.

RESULTS

NOS3 expression was significantly higher in adenocarcinoma and squamous epithelium compared with glandular metaplasia. Among the carcinomas, larger tumor size (T3/4), nodal positivity, and advanced TNM stage (III/IV) significantly correlated with increased NOS3 expression.

CONCLUSIONS

NOS3 is expressed in reflux-induced lesions of the esophagus. Glandular metaplasia shows basal levels of NOS3 that significantly increase with malignant transformation and tumor progression. The role of free radicals in carcinogenesis is being actively studied.

Masses of the salivary gland region in children

BACKGROUND

Noninflammatory masses of the salivary gland region in children are extremely rare. Therefore, very few published individual and institution-based experiences exist.

DESIGN

Retrospective chart review from 1990 through 1997.

SETTING

University-based children's hospital.

DESIGN

Patients 18 years of age or younger with a tumor in the salivary gland region. Masses of infectious origin were excluded. Hemangiomas and lymphangiomas were tallied for relative incidences only.

RESULTS

Three hundred twenty-four consecutive cases of salivary gland masses were found: 192 hemangiomas (59.2%), 89 lymphangiomas (27.5%), and 43 (13.3%) solid masses. No significant difference was found between the age at presentation of the patients with benign solid tumors and the patients with malignant solid tumors (mean + SEM age, 7.2 + 0.7 years). Sixty-one percent of the masses were found in the parotid region; 18% were localized to the submandibular gland region; and the remaining 21% were located in a minor salivary gland site. The most common benign perisalivary masses were pilomatrixomas (20.9%), followed by pleomorphic adenomas (11.6%). The most common malignant masses were mucoepidermoid carcinomas (9.3%), followed by rhabdomyosarcomas (7.0%). Treatment was individualized to the disease. Twenty-two patients had adequate data for follow-up analysis (mean + SEM follow-up, 30.0 + 8.4 months). Four patients (18.2%) experienced recurrent or residual disease and were alive with disease at last follow-up, and 100% of our population demonstrated disease-specific survival at last follow-up.

CONCLUSIONS

Vascular lesions outnumber solid tumors of the salivary gland region. The most common salivary tumors were pleomorphic adenomas, followed by mucoepidermoid carcinomas. Although certain solid salivary masses may demonstrate locally aggressive behavior, the overall prognosis is favorable. Arch Otolaryngol Head Neck Surg. 2000;126:1435-1439

Glutathione S-transferase pi in squamous cell carcinoma of the head and neck

OBJECTIVES/HYPOTHESIS

Oxidative/reductive (redox) DNA damage from radical species such as nitric oxide (NO*) are increasingly being implicated in the development of cancer. Moreover, redox-protective cellular mechanisms, such as glutathione S-transferase, may determine cellular susceptibility to this redox-mediated damage.

METHODS

Formalin-fixed, paraffin-embedded tissue samples of 11 normal oral mucosa, 15 reactive/dysplastic lesions, and 131 head and neck squamous cell carcinomas (HNSCCs) were immunohistochemically stained using a polyclonal antibody against glutathione S-transferase pi (GST-pi). Slides were reviewed in a blinded fashion by the study pathologist (G.K.H.) and intensity was graded, noting the pattern of immunostaining. These staining characteristics were compared with those obtained using monoclonal antibodies against endothelial constitutive nitric oxide synthase (ecNOS) and nitrotyrosine, a marker of NO*'s pathological nitrosylation of proteins on serial sections of the same tissue. Patient charts were reviewed and clinical data collected.

RESULTS

The expression of GST-pi was significantly increased in reactive/dysplastic and HNSCC samples compared with normal squamous mucosa (P < .001 for both). Furthermore, among the carcinomas the expression of GST-pi was significantly increased in higher-grade lesions (P < .02). The expression of GST-pi correlated highly with the expression of ecNOS and nitrotyrosine (P < .0001 for both).

CONCLUSIONS

These findings demonstrate that GST-pi is upregulated in conjunction with the NO*-generating ecNOS isoform and implicate GST-pi in protecting HNSCC from the cytotoxic effects of high concentrations of NO* found in the tumor bed.

Pulmonary complications in patients with head and neck and lung neoplasms

BACKGROUND

The occurrence of second primary neoplasms in patients with head and neck carcinoma assumes greater importance as our ability to control local disease improves. Both the primary lesions and the therapeutic interventions can predispose patients to pulmonary complications.

OBJECTIVE

To explore the incidence of pulmonary complications in patients with head and neck cancer who also undergo lung surgery.

DESIGN

Survey; case series.

SETTING

A tertiary care university hospital.

RESULTS

The clinic and hospital charts of 32 patients with multiple interventions of the head and neck and lung were retrospectively reviewed, and data were recorded on the clinical and pathologic specifics of primary and secondary neoplasms, pulmonary complications, and treatment outcomes. Twenty-eight (88%) of these patients underwent a diagnostic or therapeutic surgical procedure for a head and neck primary neoplasm. All patients (100%) underwent a pulmonary resection for malignant or nonmalignant pulmonary disease. Overall, 31 patients (97%) experienced either major or minor pulmonary complications after surgery, 51 (79%) of which occurred during the immediate postoperative course. Major complications occurred in 11 patients (34%), which were fatal in one.

CONCLUSIONS

Our data suggest that patients with head and neck cancer who also experience a second pulmonary disease requiring lung resection are at high risk of developing serious pulmonary complications. These risks should be considered in planning optimal therapy.

Increased protein nitrosylation in head and neck squamous cell carcinogenesis

BACKGROUND

Nitric oxide (NO.) and its metabolic byproducts are implicated in carcinogenesis. We examined a marker of NO.-species' pathologic protein nitrosylation, nitrotyrosine, during head and neck squamous cell carcinoma (HNSCCa) development. Materials and Methods Paraffin-embedded tissue samples of normal oral mucosa, squamous hyperplasia/dysplasia, and HNSCCa were immunohistochemically analyzed for staining intensity using an antinitrotyrosine monoclonal antibody, and correlated with retrospective clinical data.

RESULTS

Significantly higher staining was noted in reactive, dysplastic and HNSCCa samples compared with samples of normal mucosa. Additionally, significant differences in staining were found between various primary sites of the upper aerodigestive tract. Lastly, individual inflammatory cells also stained intensely.

CONCLUSIONS

Increasing amounts of nitrotyrosine staining were found in reactive/dysplastic and HNSCCa lesions compared to normal squamous mucosa. Inflammatory cell staining implicates NO. as a possible mediator of immunosuppression. Given these findings, the role of NO. in mutations leading to and the immunosuppression found in HNSCCa warrants further investigation.

The yin and yang of nitric oxide: reflections on the physiology and pathophysiology of NO

Nitric oxide (NO.) is an arginine-derived nitrogen-based radical that is rapidly becoming one of the most important molecular species to be discovered. Over the past decade, an explosion of evidence has revealed the extreme complexity of function of this seemingly simple inorganic molecule. It is now evident that NO. demonstrates a functional dualism, playing a pivotal role in numerous physiologic and pathophysiologic processes. Whether this molecule is beneficial or detrimental is dependent upon the tissue of generation, the level of production, the oxidative/reductive (redox) environment in which this radical is generated, and the presence or absence of NO. transduction elements. Nitric oxide is generated by three independent isoenzymes that resemble the p-450 enzyme superfamily in both form and function. It ultimately alters enzymatic function through covalent modification, redox interactions, and interactions with metallic functional centers. This radical is a key figure in a number of pathophysiologic processes by means of similar yet uncoordinated interactions. In consideration of the already broad spectrum of roles attributed to NO., it seems highly likely that this molecule will be implicated in an ever widening variety of functions relative to the practice of otolaryngology-head and neck surgery. This article reviews the enzymology, signal transduction mechanisms, physiology, and pathophysiology of NO. as it pertains to head and neck cancer.

Diclazuril in the horse: its identification and detection and preliminary pharmacokinetics

Diclazuril (4-chlorophenyl [2,6-dichloro-4-(4,5-dihydro-3H-3,5-dioxo-1,2,4-triazin-2-yl)pheny l] acetonitrile), is a benzeneacetonitrile antiprotozoal agent (Janssen Research Compound R 64433) marketed as Clinacox . Diclazuril may have clinical application in the treatment of Equine Protozoal Myeloencephalitis (EPM). To evaluate its bioavailability and preliminary pharmacokinetics in the horse we developed a sensitive quantitative high-pressure liquid chromatography (HPLC) method for diclazuril in equine biological fluids. MS/MS analysis of diclazuril in our HPLC solvent yielded mass spectral data consistent with the presence of diclazuril. After a single oral dose of diclazuril at 2.5 g/450 kg (as 500 g Clinacox), plasma samples from four horses showed good plasma concentrations of diclazuril which peaked at 1.077 +/- 0.174 microg/mL (mean +/- SEM) with an apparent plasma half-life of about 43 h. When this dose of Clinacox was administered daily for 21 days to two horses, mean steady state plasma concentrations of 7-9 microg/mL were attained. Steady-state levels in the CSF ranged between 100 and 250 ng/mL. There was no detectable parent diclazuril in the urine samples of dosed horses by HPLC or by routine postrace thin layer chromatography (TLC). These results show that diclazuril is absorbed after oral administration and attains steady-state concentrations in plasma and CSF. The steady state concentrations attained in CSF are more than sufficient to interfere with Sarcocystis neurona, whose proliferation is reportedly 95% inhibited by concentrations of diclazuril as low as 1 ng/mL. These results are therefore entirely consistent with and support the reported clinical efficacy of diclazuril in the treatment of clinical cases of EPM.

Nitric oxide synthase type 3 is increased in squamous hyperplasia, dysplasia, and squamous cell carcinoma of the head and neck

The implication of nitric oxide (NO*) in the multistep process of carcinogenesis prompted us to examine the expression of endothelial constitutive nitric oxide synthase (NOS3) in head and neck squamous cell carcinoma (HNSCCa). Eleven paraffin-embedded samples of normal oral mucosa, 3 reactive oral lesions, 13 samples of squamous dysplasia, and 120 specimens of HNSCCa were immunostained with an anti-NOS3 monoclonal antibody and graded on a 0 to 4+ scale of intensity. Normal squamous mucosa demonstrated very little NOS3 expression. Areas of normal mucosa, reactive mucosa, and dysplastic lesions associated with inflammation tended to demonstrate regional expression of NOS3. Reactive mucosal lesions, squamous dysplasia, and HNSCCa demonstrated a significant (p<.0001) increase in global expression of NOS3. Therefore, NOS3 is expressed very little in histologically normal squamous mucosa, while squamous hyperplasia, dysplasia, and HNSCCa express significantly more NOS3. Regional variation in NOS3 expression appears to be associated with perilesional inflammation.

Endothelial constitutive nitric oxide synthase (ecNOS) localization in normal and neoplastic salivary tissue

BACKGROUND

Nitric oxide (NO.) has been implicated in the process of carcinogenesis in various organs. This study was designed to investigate the expression of endothelial constitutive nitric oxide synthase (ecNOS) in normal and neoplastic salivary tissues.

METHODS

Paraffin-embedded tissue from 48 salivary tumors and adjacent non-neoplastic tissue was immunohistochemically evaluated for both frequency (percentage) and intensity (1-4+) of staining using a commercially available anti-ecNOS monoclonal antibody.

RESULTS

Expression of ecNOS was predominantly localized to vascular endothelium, skeletal muscle, and to salivary duct luminal epithelium in normal salivary tissue (n = 37). All salivary tumors demonstrated at least 1 + cytoplasmic staining for ecNOS without apparent correlation to most clinical parameters. A tendency toward increased frequency and intensity of ecNOS expression in oncocytic cells, relative to cells with myoepithelial or acinar differentiation, was noted.

CONCLUSIONS

Expression of ecNOS is localized to the luminal cells of normal salivary ducts. Limited expression of ecNOS was found in all the salivary gland tumors examined. This suggests a common histogenesis for this diverse group of tumors, which may reflect different degrees of differentiation toward luminal duct epithelium. The possible role of ecNOS and NO. in salivary gland carcinogenesis is intriguing and warrants further study.

Expression of the adenocarcinoma-related antigen recognized by monoclonal antibody 44-3A6 in salivary gland neoplasias

The monoclonal antibody 44-3A6 detects a cell-surface protein that has been shown to be a useful marker in distinguishing adenocarcinomas from other histologic tumor types in a variety of tissues. The objective of this study was to determine whether 44-3A6 could be used as a tool in the classification of salivary gland neoplasms. These complex tumors share overlapping pathologic features but distinct clinical outcomes. This study used 44-3A6 to immunohistochemically describe the pattern and frequency of this antigen in salivary gland neoplasms. Formalin-fixed, paraffin-embedded tissue sections of 22 benign and 26 malignant salivary tumors were evaluated. The patient population consisted of 25 (52.1%) women and 23 (47.9%) men selected from archival pathology files to reflect a range of salivary gland diseases. Normal surrounding salivary glands were found to have intense focal staining almost exclusively localized to ductal luminal cells. There was little staining of either myoepithelial or acinar cells. A wide spectrum of expression was found between and within tumor types, but a trend toward more expression of this antigen with decreasing differentiation was seen. A significant increase in staining was also seen in those tumors with ductal differentiation (n = 41) as opposed to those with predominantly acinar (i.e., acinic cell carcinoma) or myoepithelial (i.e., myoepithelioma; n = 8) differentiation (2.6 vs. 1.3, p < 0.05). No correlation was found between staining intensity and facial paralysis, pain, skin involvement, TNM stage, residual disease, or disease-free or total survival. Therefore this antigen appears to designate a duct luminal phenotype in normal and neoplastic salivary tissues.

Prevalence of binge eating disorder in obese adults seeking weight loss treatment

Binge eating has been identified as a common problem in samples of obese persons. Earlier studies found that approximately 30% of participants presenting for weight loss treatment could be diagnosed with Binge Eating Disorder (BED). This study investigated the prevalence of BED using the Questionnaire on Eating and Weight Patterns (QEWP) and the Interview for the Diagnosis of Eating Disorders (IDED) in a sample of 468 obese adults seeking weight loss treatment at two research facilities. The study found that only a small percentage of the participants met Diagnostic and Statistical Manual for Mental Disorders, 4th Revision (DSM-IV) diagnostic criteria for BED using either the IDED (1.3%) or QEWP (7.3%). A larger percentage of the sample (10.7% based on the IDED and 20.5% based on the QEWP) reported binge eating, but did not endorse all criteria necessary to warrant a diagnosis of BED. The primary finding of the study was that the prevalence of BED in treatment seeking obese adults was much lower than was reported in previous studies. Also, there was significant discrepancy in prevalence rates of BED as defined by self-report and interview assessment methods, with the interview method yielding lower estimates of prevalence. These findings suggest that the prevalence of BED may be lower than estimates of earlier reports. We recommend that future studies of BED use reliable and valid interview methods and that this research focus on more diverse populations, including men and a variety of racial and ethnic groups.

Seroprevalence of antibodies to Sarcocystis neurona in horses residing in a county of southeastern Pennsylvania

OBJECTIVE

To determine seroprevalence of Sarcocystis neurona-specific antibodies in a population of horses residing in Chester County, Pa.

DESIGN

Prevalence survey.

SAMPLE POPULATION

117 serum samples from selected members of a population of 580 Thoroughbred horses.

PROCEDURE

Serum was analyzed for antibodies to Sarcocystic neurona, using a western blot. Information regarding age, sex, and housing of horse was obtained by questionnaire. Data were analyzed, using multivariable logistic regression.

RESULTS

Seroprevalence was 45.3% (95% CI, 36.3 to 54.3%). A relationship was not found between seroprevalence and sex of horse. Seroprevalence was greater in older horses (logistic regression; P = 0.16).

CLINICAL IMPLICATIONS

High seroprevalence of antibodies to S neurona and the lack of neurologic deficits among horses sampled indicate that positive results of serologic examination alone are of limited value for diagnosis of equine protozoal myeloencephalitis. Clinical signs consistent with the disease are the most important consideration in accurate diagnosis.

Cytoplasmic localization of endothelial constitutive nitric oxide synthase in endometrial carcinomas

BACKGROUND

Production of nitric oxide by nitric oxide synthase (NOS) has been implicated in numerous physiologic and pathophysiologic processes including mutagenesis. This study was designed to examine the expression of the endothelial constitutive isoform of NOS (ecNOS) in endometrial carcinomas.

METHODS

Fifty endometrial carcinomas (42 endometrioid, 4 serous papillary, 2 clear cell, and 2 adenosquamous carcinomas) and 21 normal endometrial gland tissue specimens (5 cases of proliferative, 5 early secretory, 5 mid-secretory, and 5 late secretory and 1 menstrual phase endometrium), previously formalin fixed and paraffin embedded, were immunostained using a commercially available anti-ecNOS monoclonal antibody. Localization of ecNOS staining to the plasma membrane, cytoplasm and nuclei was graded with respect to overall staining intensity (0-3+ scale) and frequency (percentage of immunoreactive cells).

RESULTS

Relatively little staining for ecNOS was localized to the plasma membrane in either normal or neoplastic tissues. Normal and hyperplastic endometrial glands demonstrated moderate cytoplasmic and weak nuclear staining in a small percentage of cells. While ecNOS expression was most prominent in epithelial cells, weak expression was also rarely noted in endometrial stroma, blood vessel walls, and endothelium. We found a broad range of ecNOS expression in endometrial carcinomas, predominantly localized to the cytoplasm and nuclei. No statistically significant difference in ecNOS staining frequency or intensity was found between different histologic subtypes of endometrial carcinomas. No apparent correlation was found between ecNOS expression and tumor stage, grade, extension to the lower uterine segment or cervix, nodal or distant metastases, recurrence, or final patient status among patients with endometrioid adenocarcinomas. Endometrioid tumors invading more than 1/2 of myometrial thickness (n = 18) had significantly higher cytoplasmic staining intensity than those tumors limited to the inner 1/2 of myometrium (n = 27; 2.0 vs. 1.3, p < 0.04). Furthermore, a trend toward shorter disease-free survival was noted with increased staining intensity and decreased staining frequency.

CONCLUSIONS

Cytoplasmic and nuclear expression of ecNOS, which is primarily limited to the glandular elements of normal endometrium, is also found to be expressed in endometrial carcinoma. Increased ecNOS staining intensity and decreased frequency tends to correlate with decreased disease-free survival. Lastly, increased cytoplasmic ecNOS staining intensity correlates with increased myometrial invasion.

Tumor necrosis factor alpha inhibits hepatocyte mitochondrial respiration

Although direct cytotoxicity is a well-established phenomenon of tumor necrosis factor alpha (TNF alpha)-induced tissue damage, the intracellular events leading to cell death are still poorly understood. To study the cytotoxic effects of TNF alpha on normal parenchymal cells, rat hepatocytes were purified and incubated with various concentrations of TNF alpha. Mitochondrial respiration, total protein synthesis, and enzyme release were measured to assess metabolic performance and cell integrity. Treatment with TNF alpha suppressed mitochondrial respiration in a concentration-dependent fashion, resulting in a reduction of the activity of complex I of the respiratory chain to 67.0 +/- 3.5% of that of untreated hepatocytes by 2000 U/mL TNF alpha. Under these conditions protein synthesis and the release of intracellular enzymes were significantly increased. Both hepatocellular enzyme release and inhibition of mitochondrial respiration appear to be associated with the generation of reactive oxygen intermediates by the hepatocyte itself, because oxygen radical scavengers prevented these adverse effects of TNF alpha. Inhibition of protein synthesis by cycloheximide as well as addition of cyclic adenosine monophosphate synergistically enhanced the suppression of mitochondrial respiration by TNF alpha, resulting in complex I activity of 6.9 +/- 1.6% and 24.9 +/- 2.9% of that of untreated cells. These data indicate that inhibition of mitochondrial respiration is one of the mechanisms by which TNF alpha induces tissue injury.

Hepatocyte modulation of Kupffer cell prostaglandin E2 production in vitro

It is likely that dynamic interactions between hepatocytes and Kupffer cells contribute to the responses of these cell types both under normal conditions and during sepsis. In this study, we examined the influences of hepatocytes on the concentration of the inflammatory mediator PGE2 in Kupffer cell cultures. Evidence to suggest that cultured rat hepatocytes both metabolize PGE2 and produce a substance that promotes LPS-stimulated Kupffer cell PGE2 biosynthesis include the following: 1) PGE2 levels in Kupffer cell: hepatocyte coculture were lower than the levels in Kupffer cell cultures early after LPS stimulation; 2) 36 h after LPS, coculture PGE2 levels exceeded the levels in Kupffer cell cultures despite the demonstrated capacity for hepatocytes to metabolize PGE2; 3) a transferable, non-dialyzable, and heat-unstable factor in hepatocyte supernatant promoted PGE2 production when added to Kupffer cells with LPS or after LPS; 4) there was no increased PGE2 synthesis when the hepatocyte supernatant was added without LPS or if hepatocyte supernatant was preincubated with the Kupffer cells for 6 or 18 h before LPS administration; 5) there was an inability of the hepatocyte factor to promote PGE2 production in response to other macrophage-activating agents, including calcium ionophore A23187 or phorphol myristate acetate; and 6) there was no increased cell replication or protein synthesis in the Kupffer cell cultures following hepatocyte supernatant incubation. The increased Kupffer cell PGE2 production by the hepatocyte supernatant was not due to contamination of the hepatocyte supernatant by endotoxin or PGE2. These in vitro results raise the possibility that hepatocytes have the capacity to modulate local PGE2 levels by two distinct mechanisms. Hepatocytes can metabolize PGE2 as well as release factor(s) which promote LPS-induced PGE2 production by Kupffer cells.

Hepatocytes enhance Kupffer cell-mediated tumor cell cytostasis in vitro

Kupffer cells (KC) are believed to play a major role in protecting the liver from metastases. In vitro, activated KC mediate both tumor cell cytostasis and cytolysis. Because hepatocytes (HC) occupy a position adjacent to KC in vivo, we investigated the influence of HC on KC tumoricidal activity. Using an in vitro assay of KC-mediated tumor cell cytostasis against murine P815 mastocytoma cells, we found that the presence of HC in the culture profoundly increased KC tumoricidal activity. HC enhanced KC inhibition of P815 proliferation and lowered the concentration of lipopolysaccharide and interferon-gamma necessary to activate the KC to a tumoricidal state. This stimulatory HC effect was dependent on the number of HC present and was transferable in cell-free supernatants, indicating that it was mediated by a soluble secreted product of HC. Furthermore, unlike other macrophage-priming or -potentiating factors, the transferable HC factor(s) was effective only if added simultaneously with lipopolysaccharide or interferon-gamma and not effective if added before these activating agents. These data show that HC produce a soluble mediator that enhances KC tumoricidal activity, suggesting that HC and KC interactions may be critical to the antitumor defense mechanisms of the liver.

An L-arginine-dependent mechanism mediates Kupffer cell inhibition of hepatocyte protein synthesis in vitro

The hepatic failure associated with severe sepsis is characterized by specific, progressive, and often irreversible defects in hepatocellular metabolism (1). Although the etiologic microbe can often be identified, the direct causes and mechanisms of the hepatocellular dysfunction are poorly understood. We have hypothesized that Kupffer cells (KC), which interact with ambient septic stimuli, respond by providing signals to adjacent hepatocytes (HC) in sepsis . Furthermore, we have provided evidence (2, 3) that KC activated by LPS from Gram-negative bacteria can induce profound changes in the function of neighboring HC in coculture. In our model, coculture of either KC (2) or peritoneal macrophages (Mphi)(3) with HC normally promotes HC protein synthesis ([(3)H]leucine incorporation). The addition of LPS or killed Escherichia colt' to such cocultures induces a profound decrease in HC protein synthesis, as well as qualitative changes ([(35)S]methionine, SDS-gel electrophoresis) in protein synthesis without inducing HC death (2, 3) . In this report we show that the inhibition in protein synthesis is mediated via an L-arginine-dependent mechanism. The metabolism of L-arginine by activated Mphi to substances with cytostatic and even lethal effects on target cells is a relatively recent discovery. After the description by Stuehr and Marletta (4, 5) that LPS- triggered Mphi produced nitrite/nitrate (NO(2)(-)/NO(3)(-)), Hibbs et al. (6, 7) and Iyengar et al. (8) demonstrated that L-arginine was the substrate for the formation of both these nitrogen end products and citrulline. A role for the arginine-dependent mechanism in Mphi tumor cytotoxicity (6, 7) and microbiostatic activity (9) has been suggested. However, the in vivo functions of this novel Mphi mechanism have not yet been defined, but it is possible that there are both physiologic as well as pathologic roles. Our in vitro results raise the possibility that some metabolic responses to microbial invasion maybe partially mediated by the L-arginine-dependent mechanism. What other metabolic responses are affected and the possible pathologic consequences remain to be studied.

Effect of interleukin 2 on Kupffer cell activation. Interleukin 2 primes and activates Kupffer cells to suppress hepatocyte protein synthesis in vitro

Interleukin 2 (IL-2) is an essential mediator of the immune response and has also been shown to be protective in experimental models of sepsis. Macrophages have IL-2 receptors but their function is unknown. We investigated the effect of IL-2 on Kupffer cells, the fixed macrophages of the liver, using an in vitro rat hepatocyte-Kupffer cell coculture system. In this model, endotoxin (lipopolysaccharide) triggers Kupffer cells to induce suppression of hepatocyte protein synthesis. We found that pretreatment with 10 U/mL or more of IL-2 primed Kupffer cells, significantly reducing the concentration of lipopolysaccharide necessary to trigger Kupffer cell-mediated suppression of hepatocyte protein synthesis. Higher concentrations of IL-2 (greater than or equal to 1 x 10(4) U/mL) alone were capable of priming and triggering Kupffer cells to suppress hepatocyte protein synthesis. These data show that IL-2 increases Kupffer cell sensitivity to endotoxin, suggesting that IL-2 may play an important role in regulating macrophage responses to septic stimuli.