Immunohistochemical expression of transforming growth factor alpha and epidermal growth factor receptor in pancreatic endocrine tumors.

Coexpression of transforming growth factor alpha (TGF-alpha) and its receptor epidermal growth factor receptor (EGFR) is known to be associated with aggressive biologic behavior and adverse clinical outcome in a variety of tumors, including pancreatic adenocarcinomas. However, very little information is currently available as to whether this is true of pancreatic endocrine tumors (PETs) as well. Thirty-five PETs were retrospectively studied for immunohistochemical expression of TGF-alpha, the intracellular and extracellular domains of EGFR, and various hormonal secretory products. Proliferative activity was additionally studied (in 20 cases only) using the MIB-1 antibody. Thirty-one (89%) of 35 tumors were reactive for 1 or more of the peptide hormones tested; 22 (63%) tumors were positive for TGF-alpha; and 23 (65%) were positive for the intracellular and/or extracellular domain of EGFR. Based on their TGF-alpha and EGFR expression, these tumors could be classified into 4 groups. Of the 10 tumors in group I (positive for TGF-alpha and the complete EGFR molecule), 3 were malignant, 6 were >2 cm in diameter, 5 were functional, and 1 had a proliferative index of >40%. The 12 tumors in group II (positive for TGF-alpha but negative for the intracellular and/or extracellular domain of EGFR) included 4 malignant tumors, 4 PETs >2 cm in diameter, 8 functional, and 1 with a proliferative index of >40%. The 7 PETs in group III (positive for the intracellular/extracellular domain of EGFR alone) included 3 malignant tumors, 3 PETs >2 cm in diameter, and 3 functional tumors. The 6 tumors in group IV (completely negative for both TGF-alpha and EGFR) included 4 malignant tumors, 3 PETs >2 cm in diameter, and 4 functional lesions. Therefore, immunohistochemical expression of TGF-alpha and EGFR, either alone or in concert, shows no correlation with size, functional status, secretory profile, or biologic behavior and hence cannot be used as a marker of malignancy in this group of tumors.

Rabeprazole for the prevention of pathologic and symptomatic relapse of erosive or ulcerative gastroesophageal reflux disease. Rebeprazole Study Group.

OBJECTIVE: We evaluated the effectiveness and safety profile of 10 and 20 mg of rabeprazole, a new proton pump inhibitor, once daily versus placebo in preventing endoscopic and symptomatic relapse for up to 1 yr among patients with healed erosive or ulcerative gastroesophageal reflux disease (GERD). METHODS: The 52-wk trial used a multicenter, randomized, double-blind, parallel-group design in which 209 men and women were assigned to 10 or 20 mg of rabeprazole once daily in the morning or placebo. RESULTS: Both rabeprazole doses were significantly superior to placebo in preventing endoscopic relapse (p < 0.001), and 20 mg was significantly more effective than 10 mg (p < 0.04). Both doses were also significantly superior to placebo in reducing the frequency and severity of heartburn relapse (p < 0.001). When adjusted for differences in exposure to study medication, no significant differences were found in the incidence of adverse events. No clinically significant changes were found regarding clinical laboratory parameters, vital signs, electrocardiograms, ophthalmological evaluations, body weight, serum gastrin, and enterochromaffin-like cell histology. CONCLUSIONS: Once-daily therapy with 10 or 20 mg of rabeprazole effectively prevents pathological and symptomatic GERD relapse. The 20-mg dose is significantly more effective than the 10-mg dose in preventing endoscopic recurrence. Treatment was well tolerated, and no clinically significant safety findings emerged. Our findings support rabeprazole's efficacy in preventing GERD recurrence with excellent tolerability and a short-term favorable safety profile.

A novel apoptotic pathway in quiescent lymphocytes identified by inhibition of a post-proline cleaving aminodipeptidase: a candidate target protease, quiescent cell proline dipeptidase.

The vast majority of lymphocytes in vivo persist in a quiescent state. These resting lymphocytes are maintained through a cellular program that suppresses apoptosis. We show here that quiescent PBMC, but not activated PBMC or transformed lymphocytes, die in the presence of highly specific post-proline aminodipeptidase inhibitors. This form of death has the hallmarks of apoptosis, such as phosphatidylserine externalization and loss of mitochondrial transmembrane potential. However, it differs from apoptosis induced by gamma irradiation in the same cells or by Fas ligation in transformed lymphocytes in terms of caspase involvement. In addition, the aminodipeptidase inhibitor-induced cell death, but not gamma-irradiation-mediated apoptosis, can be prevented by inhibition of the proteasome complex. The target of these inhibitors is not CD26/DPPIV, but probably a novel serine protease, quiescent cell proline dipeptidase, that we have recently isolated and cloned. These studies will yield a better understanding of the requirements and the mechanisms that mediate quiescent lymphocyte homeostasis in vivo.

Morphology and other prognostic factors of hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma is a malignancy found worldwide that has typically poor prognosis despite treatment. Although several studies have dealt with prognostic factors, just a few detailed analyses of large series correlating the pathology of hepatocellular carcinoma with prognosis are available. The present study was undertaken to address this limitation. PATIENTS AND METHODS: Our prior clinical study described 432 patients, but sufficient tissue was available for evaluation in only 299 patients. Of these, 224 samples contained primary hepatocellular carcinoma, while the remainder contained only metastatic tumor. Characteristics evaluated included degree of tumor differentiation, associated cirrhosis or hepatitis, presence of cytoplasmic inclusion bodies, and blood vessel invasion by the neoplasm. RESULTS: Of the 224 patients, 71% were male, 65% white, and 73% over the age of 45 years. Ninety-one percent were from North America. A total of 42 patients were found to have cirrhosis. Thirty-five percent had cytoplasmic inclusion bodies, and 25% showed evidence of blood vessel invasion. Tumor response rates (tumor shrinkage) were low (8%) regardless of treatment. Presence of cytoplasmic eosinophilic inclusion bodies and blood vessel invasion were not associated with increased survival. Some histopathologies (pelioid, spindle cell, fibrolamellar) were associated with a better prognosis. Patients with a predominant trabecular pattern (43%) did particularly poorly. Although sex was significantly associated with survival using a univariate analysis, this effect disappeared in a multivariate Cox model that adjusted simultaneously for other factors. CONCLUSION: This investigation suggests that histologic subtype and clinical features may provide useful prognostic information in hepatocellular carcinoma. Poorer survival was observed in males, older patients with poorly differentiated tumors, or when associated with cirrhosis. Age younger than 45 years was a good prognostic factor, and presence of cirrhosis had an adverse effect on survival.

Histological esophagitis: clinical and histological response to omeprazole in children.

Many children with esophagitis demonstrate histological changes without gross evidence of esophagitis by esophagoscopy. The effect of omeprazole on the histological healing of esophagitis in children is unknown. Therefore, the aim of this study was to determine the effect of omeprazole on refractory histological esophagitis in pediatric patients. Eighteen patients with histological evidence of esophagitis and recurrent symptoms despite therapy with H2-receptor antagonists and prokinetic agents were prospectively treated with omeprazole. Dosing was adjusted by monitoring intragastric pH, and esophagoscopy was repeated after 8-12 weeks of omeprazole treatment. Two patients did not complete the study due to either worsening symptoms or hypergastrinemia. Of the remaining patients, 76% were asymptomatic with omeprazole treatment and 24% reported improvement in their symptoms. Approximately 40% demonstrated complete histological healing of their esophagitis. Three patients (17%) had persistent elevations in serum gastrin levels while on omeprazole treatment, which was associated with both younger patient age and higher omeprazole dosing; however, all elevated gastrin levels returned to normal after discontinuation of the medication. All patients had recurrence of their symptoms after completing a course of omeprazole, even patients with complete histological healing. Omeprazole is efficacious in treating children with esophagitis refractory to H2-receptor antagonist and prokinetic agents. However, none of the patients were able to discontinue acid suppressive therapy even after documented healing of their esophagitis.

Combined chemoradiotherapy vs. radiotherapy alone for early stage squamous cell carcinoma of the esophagus: a study of the Eastern Cooperative Oncology Group.

Squamous carcinoma of the thoracic esophagus has an extremely poor prognosis. This study, EST-1282, was undertaken by the Eastern Cooperative Oncology Group (ECOG) to determine whether the combined use of 5-fluorouracil (5-FU), mitomycin C, and radiation therapy improved the disease-free survival and overall survival of patients with carcinoma of the esophagus, compared to those who received radiation therapy alone. Two- and 5-year survivals were 12% and 7% in the radiation alone arm and 27% and 9% in the chemoradiation arm. Patients treated with chemoradiation had a longer median survival (14.8 months), compared to patients receiving radiation therapy alone (9.2 months). This difference was statistically significant. The same pattern of survival was noted in almost all subgroups independent of whether surgical resection was performed.

Pancreatic acinar cell clusters in pediatric gastric mucosa.

Although clusters of pancreatic acinar cells (CPACs) have been reported in gastric mucosa of adults, they have not been described in children. We reviewed 283 pediatric gastric (239 antral and 44 corpus) mucosal biopsies during a 2-year period and detected CPACs in 10 antral biopsy samples. These biopsy samples were stained immunohistochemically for pancreatic exocrine markers (trypsin, chymotrypsin, alpha-amylase, and lipase) and a panel of regulatory substances (insulin, glucagon, somatostatin, pancreatic polypeptide, gastrin, and serotonin). Double immunostaining for colocalization of chromogranins and trypsin as well as mucin and trypsin also were performed on all cases. CPACs were seen in antral mucosa in a background of either normal or minimally inflamed mucosa, without any atrophy or metaplasia, and were positive for all pancreatic exocrine markers. Stray chromogranin-positive cells in the CPACs were also immunopositive for somatostatin, gastrin, or serotonin. All CPACs showed a few hybrid (amphicrine) cells that coexpressed both chromogranin and trypsin. In one case, ultrastructural examination showed such cells to contain both zymogen and neurosecretory granules. Although the presence of CPACs exclusively in the antrum is most likely the result of a sampling bias, the presence of hybrid cells with an amphicrine phenotype suggests that CPACs probably result from an aberration of stem cell differentiation.

Parietal cell protrusions in gastric ulcer disease.

Oxyntic mucosal biopsy specimens from patients receiving omeprazole therapy have been described as frequently showing characteristic tonguelike protrusions of parietal cell cytoplasm (PCP) into the gland lumen. Although protrusion of parietal cell cytoplasm is believed to be associated with omeprazole therapy and has been implicated in the histogenesis of fundic gland polyps, we have observed it in a wide variety of different conditions unrelated to peptic ulcer disease or omeprazole therapy. To establish the incidence of PCP and analyze its relationship to gastritis, gland dilatation, cystic change, and fundic gland polyps, we studied 400 gastric mucosal biopsy specimens from gastric ulcer patients who were not receiving omeprazole therapy and who did not receive any medications for at least 2 weeks. Severity of each of these changes was graded on a scale of I to III. PCP was observed in oxyntic mucosal biopsy specimens from 60 (15%) patients and was associated with varying grades of chronic superficial or interstitial gastritis in 25 (Helicobacter pylori was identified in 12). Although chronic atrophic gastritis, cystic change, or fundic gland polyps were not identified in any of the cases with PCP, gland dilatation was present in 25 of 60 (42%) biopsy specimens. No consistent linear correlation was observed between increasing grades of PCP and gastritis or gland dilatation. Our findings of PCP in 15% of gastric ulcer patients who were off all medications for 2 weeks indicate that PCP is not always related to omeprazole usage. It appears to be a change encountered in a wide variety of diverse settings and, therefore, should not be used to monitor omeprazole therapy. In gastric ulcer patients, there is no linear correlation between PCP and gland dilatation or severity of gastritis. The lack of association of PCP with such cardinal features of fundic gland polyps as gland dilatation and cystic change suggests that PCP per se has little if any role in the development of such polyps. The exact clinical and functional significance of PCP remain to be established and merits further investigation.

Pancreatic metaplasia of the gastric mucosa in pediatric patients.

UNLABELLED: Antropyloric and intestinal-type metaplasia of gastric columnar epithelial cells occurs commonly in the setting of atrophic gastritis in both adults and pediatric patients. Pancreatic metaplasia of gastric mucosa, although less common, has been reported in a variety of clinical conditions in adult patients, but not in the pediatric population. OBJECTIVES: The aim of this retrospective review was to characterize the clinical and pathological findings in pediatric patients found to have histological and immunohistochemical evidence of pancreatic metaplasia of the gastric mucosa in biopsies taken at the time of upper endoscopy. METHODS: Patients with histological evidence of pancreatic metaplasia of the gastric mucosa were prospectively identified. Their individual medical records were then reviewed for presenting symptoms, pertinent laboratory data, gross findings on endoscopy, radiological features, diagnosis, and subsequent therapy. RESULTS: Of the six children (ages, 8-18 yr; mean, 13.0 yr), with pancreatic metaplasia of the gastric mucosa, two children each had gastroesophageal reflux disease and chronic abdominal pain, whereas one child had a duodenal ulcer and one child had nodular gastritis. Iron deficiency anemia was present in four of six patients; three of four patients with this finding presented with hematemesis. All biopsies were negative for Helicobacter pylori. CONCLUSIONS: Whereas pancreatic metaplasia of the gastric mucosa is strongly associated with chronic atrophic gastritis in adults, its occurrence in children who do not have atrophic gastritis raises the possibility that it may be a developmental phenomenon of gastric mucosal differentiation. The clinical significance of this finding remains to be determined; and its association with iron deficiency in children requires further study.

Cytogenetic and immunohistochemical analysis of an adult anaplastic neuroblastoma.

Neuroblastomas in children are common tumors and are characterized by a number of recurrent cytogenetic and molecular changes. Adult neuroblastomas are rare, and their relationship to pediatric neuroblastomas is not clear. We report an anaplastic neuroblastoma presenting in a 28-year-old man. Histopathologic identification of the tumor as a neuroblastoma was problematic, and the initial diagnosis was poorly differentiated sarcoma. Tumor cells expressed immunoreactivity for tyrosine hydroxylase in addition to generic neuroendocrine markers, consistent with catecholamine-synthesizing ability. They also extended long, branching neurites in vitro. The tumor was positive for immunoreactive trkA. The karyotype after 6 days in culture was found to be 42,XY with multiple chromosomal abnormalities. The only abnormality shared with pediatric neuroblastomas was a rearrangement of chromosome 17q. Double minute chromosomes or homogeneously staining regions associated with N-myc amplification were not present. To our knowledge, this is the first reported karyotype of an adult neuroblastoma. The cytogenetic findings, together with expression of trkA, suggest that the tumor was more closely related to the favorable prognosis neuroblastomas of infancy than to the poor prognosis tumors that occur in older children, despite its unfavorable histology.

Immunohistochemical expression of transforming growth factor alpha and epidermal growth factor receptor in gastrointestinal carcinoids.

Transforming growth factor-alpha (TGF-alpha), a potent growth factor belonging to the epidermal growth factor family, exerts its role in the proliferation and differentiation of normal and neoplastic cells by binding to epidermal growth factor receptor (EGFR). Coexpression of TGF-alpha and EGFR in carcinomas is believed to confer growth advantage to tumor cells. To evaluate their role in such indolent tumors as gastrointestinal (GI) carcinoids, we investigated the immunohistochemical expression of TGF-alpha and EGFR in 25 GI carcinoids (nine foregut, 13 midgut, and three hindgut) and studied the correlation of their expression with the secretory and clinicopathologic profiles of these tumors. TGF-alpha was expressed in 18 (72%) of these tumors, and whereas 16 of 17 tumors showed immunopositivity for the extracellular domain of EGFR, none expressed its intracellular domain. Ten TGF-alpha-positive tumors were positive for serotonin, seven for somatostatin, three for calcitonin, and one tumor each for gastrin, glucagon, pancreatic polypeptide, vasoactive intestinal peptide, and growth hormone-releasing factor, respectively. Seven TGF-alpha-positive tumors were multihormonal, eight were monohormonal, and three were completely nonreactive for the regulatory substances studied. Except for its correlation with 5-hydroxytryptamine (serotonin) expression by the tumor cells, expression of TGF-alpha showed no significant association with other pathologic attributes, for example, the site of origin, size, depth of intramural penetration, metastases, and the secretory profiles of the tumors. These findings indicate that although TGF-alpha is expressed by a high proportion of GI carcinoids, the absence of its intact receptor molecule (EGFR) on the tumor cells renders it functionally ineffective as a growth factor. Thus, unlike in carcinomas of the GI tract, TGF-alpha appears to play no role in the growth and progression of GI carcinoids, which perhaps explains the indolent behavior and slow biological progression of GI carcinoids.

Composite pheochromocytoma/ganglioneuroma of the adrenal gland associated with multiple endocrine neoplasia 2A: case report with immunohistochemical analysis.

We report a case of composite pheochromocytoma/ganglioneuroma arising in a background of diffuse and nodular medullary hyperplasia in the adrenal gland of a 34-year-old man with multiple endocrine neoplasia 2a (MEN 2a). Cells were histologically classified as chromaffin or chromaffin-like (small typical-appearing pheochromocytoma cells), neuron-like (possessing ganglion cell morphology), and intermediate. We speculate that these cell types may represent a spectrum of differentiation of a neoplastic clone, with the intermediate cells representing a transitional stage between chromaffin cells and neurons. All three cell types in the composite tumor and all chromaffin cells in both nodular and nonnodular areas of the remaining medulla were strongly immunoreactive for tyrosine hydroxylase, the rate-limiting enzyme in catecholamine synthesis. In contrast, neuron-like cells (and to a variable extent intermediate cells) displayed selective loss of expression of phenylethanolamine-N-methyltransferase (PNMT), the enzyme that synthesizes epinephrine. Proliferative activity of the composite tumor and both the nodular and nonnodular medulla was studied by staining for the endogenous cell proliferation antigen Ki-67, using monoclonal antibody MIB-1. MIB-1 labeling was highest in Schwann cell areas of the composite tumor, followed by chromaffin-like cells in the composite tumor and in the separate nodules. Labeling was absent in neuron-like cells, consistent with the cells' postulated status as terminally differentiated derivatives of a chromaffin cell precursor, and was highly variable in nonnodular areas of the medulla. The latter observation suggests topographical variation in signals that drive chromaffin cell proliferation in MEN.

Results of combined modality therapy for patients with anal cancer (E7283). An Eastern Cooperative Oncology Group study.

BACKGROUND: This prospective study assessed combined modality therapy of patients with International Union Against Cancer classification T1-4 N0 M0 anal cancer. METHODS: Protocol therapy consisted of a dose of 4000 cGy to the pelvis, anus, and perineum, followed by a 1000-1300 cGy boost. Infusions of 5-fluorouracil and mitomycin-C were administered when radiation therapy began. A second infusion of 5-fluorouracil was administered 28 days later. Biopsy was performed 6-8 weeks after completion of treatment. Positive biopsy findings resulted in abdominal-perineal resection. RESULTS: Survival at 7 years for 50 eligible patients was 58%. White patients and those with favorable performance status had significantly better survival. Of the 46 patients evaluable for response, 34 had a complete response, 11 had a partial response, and 1 had no response. Seven-year survival for partial responders was 53%. Freedom from locoregional progression was 80% at 7 years. CONCLUSION: Treatment with a combination of chemotherapy and radiation therapy is effective for patients with anal cancer. The investigation of methods of improving therapy is warranted.

Pancreatic metaplasia in Barrett's esophagus. An immunohistochemical study.

While pancreatic metaplasia has been observed in gastric mucosa of patients with chronic gastritis, it has not been described in ectopic gastric mucosa. We have identified focal clusters of cells resembling pancreatic acinar cells (CPACs) in 11 of 350 biopsies of Barrett's mucosa from 120 patients with Barrett's esophagus enrolled in a clinical efficacy trial of omeprazole versus ranitidine for treatment of gastroesophageal reflux disease. Three additional cases from our surgical files were also studied. Immunoreactivity for trypsin and chymotrypsin was present in the CPACs of all 14 cases, while stains for alpha-amylase and lipase were each positive in 12 of 13. A few cells in the CPACs were also positive for chomogranins (12 of 13 cases), serotonin (seven of 13 cases), somatostatin (three of 12), gastrin (four of 11), and pancreatic polypeptide (two of 13). No staining was seen for insulin or glucagon. Ultrastructural studies performed in one case showed features of pancreatic exocrine and endocrine (PP-type) cells in cells within CPACs. These results collectively indicate that the CPACs are aggregates of true pancreatic acinar cells admixed with a few endocrine cells. This pancreatic parenchyma in Barrett's mucosa is most likely of metaplastic origin and could be derived from the transitional zone cells or from pluripotent stem cells in the esophageal mucosa or from metaplasia of mucus cells. While the development of pancreatic metaplasia in Barrett's esophagus appears to be unrelated to drug therapy, the clinical relevance of this distinctive histological finding needs further investigation.

A light microscopical, ultrastructural and immunohistochemical study of spindle-cell adrenocortical tumours of ferrets.

Twelve adrenocortical tumours with a variable spindle-cell component in ferrets (six spayed females, three intact females, two castrated males, and one intact male) were examined by light microscopy. One tumour with a moderate spindle-cell component was examined ultrastructurally, and three tumours were studied immunohistochemically. Light microscopy revealed a spindle-cell component in the tumours that varied from a few such cells occupying the stroma between packets of adrenocortical cells to cells in such large numbers that they formed almost the entire substance of the tumour. By light microscopy these spindle cells resembled smooth muscle cells, and the ultrastructural findings, particularly the presence of thin contractile filaments, suggested that the spindle cells were of smooth muscle origin. Immunohistochemical staining revealed that the spindle cells were negative for cytokeratins and S-100 protein but positive for smooth muscle actin. Desmin was readily demonstrated in two tumours but not in the other examined. Vimentin was variable, generally producing a small to moderate amount of reaction product.

Hyperplastic proliferations of the ECL cells.

Enterochromaffin-like (ECL) cells are the dominant endocrine cell type in the oxyntic mucosa. Normally regarded as histamine-producing cells, they are exquisitely sensitive to the trophic action of gastrin and undergo a hyperplastic increase in a variety of hypergastrinemic conditions. A hyperplasia-neoplasia sequence of ECL-cell proliferations has been recently proposed, following the realization that increasingly severe degrees of ECL-cell hyperplasias over a period of several years can progress to ECL-cell carcinoids. Such carcinoids arising in patients with chronic hypergastrinemia differ both in their clinical and pathologic profiles from the sporadic carcinoids that occur in normogastrimenic individuals and, therefore, need to be distinguished from them. This distinction is particularly important for their clinical management, since antrectomy appears to be of benefit in ECL carcinoids of hypergastrinemic patients.

Folate deficiency enhances the development of colonic neoplasia in dimethylhydrazine-treated rats.

In patients with ulcerative colitis, epidemiological work has suggested an association between low folate status and an increased risk of colonic neoplasia. The aim of the present study was to determine if experimental folate deficiency increases the likelihood of developing neoplasia in rats treated with the carcinogen dimethylhydrazine. Weanling male Sprague-Dawley rats were fed with an amino acid-defined diet containing either 8 or 0 mg/kg folic acid. After 5 weeks of defined diet, weekly s.c. injections of dimethylhydrazine (20 mg/kg) were administered to both groups. Serum, whole blood, liver, and colonic folate concentrations at the time of sacrifice were significantly lower in folate-depleted animals (P less than 0.001). There were significant differences in the incidence of colonic neoplasia between the two groups after 20 weeks of dimethylhydrazine exposure: folate-deficient rats had a greater incidence of dysplasia (6 of 7 versus 2 of 7 animals; P less than 0.05) and carcinoma (6 of 7 versus 1 of 7 animals; P less than 0.01). Furthermore, a significantly greater proportion of folate-replete rats than folate-deficient rats were free of neoplastic lesions (5 of 7 versus 0 of 7 animals; P less than 0.05). These results suggest that, in this animal model, folate deficiency increases the risk of malignancy when there is an underlying predisposition to colorectal cancer.

The cell-mediated response to schistosomal antigens at the clonal level. In vivo functions of cloned murine egg antigen-specific CD4+ T helper type 1 lymphocytes.

It is now well established that the granulomatous inflammation surrounding the eggs of Schistosoma mansoni is mediated by Th lymphocytes. Our laboratory has recently cloned murine CD4+ Th cells specific for schistosomal egg Ag (SEA). In the current study, SEA-specific IL-2-producing Th1 clones were tested for their ability to mediate local delayed-type hypersensitivity (DTH) reactions, as well as granuloma formation in vivo. Marked delayed-onset erythema and induration developed in footpads of normal syngeneic hosts injected with SEA together with SEA-specific Th1 clones. Histologic examination of these lesions revealed typical, predominantly mononuclear, cell infiltrates characteristic of DTH reactions. Conversely, no reactions were observed in allogeneic hosts, in the absence of SEA, or with the use of a control Th1 clone. Moreover, adoptive transfer of cloned SEA-specific Th1 cells to normal syngeneic mice mediated, in 4 days, the formation of vigorous granulomas around schistosomal eggs embolized in the lungs. Such granulomas, which were quantitated by computer-assisted morphometric analysis, were comparable in size to those elicited by lung-embolized eggs in SEA/CFA-immunized mice. In contrast, significantly smaller granulomas were observed in normal recipients of eggs plus a control Th1 clone or of eggs alone. Our data indicate that Ag-specific, MHC-restricted, local DTH reactions, as well as egg granuloma formation in vivo, can be mediated by monoclonal SEA-specific Th1 cells. They suggest that T cell sensitization to only small numbers of SEA determinants may be sufficient to elicit the hepatointestinal granulomatous inflammation associated with schistosomiasis.

Distinctive unclassified mesenchymal tumor of the digit of dogs.

Four examples of a mesenchymal tumor of undetermined histogenesis occurred in three mixed-breed dogs and one Yorkshire terrier. All tumors occurred as solitary, soft to firm, solid, tan, and ulcerated masses in the digits of dogs aged 11 to 15 years. The compact cellular tumor had cells with anisokaryotic round, oval, or irregular nuclei, some of which were multinucleated. The neoplastic cells appeared to arise in the tissue near the third phalanx in the area of dense collagenous trabeculae located proximal to the fat pad and sweat glands. The unclassifiable cells had some features of histiocytes by transmission electron microscopy, but failed to stain for lysozyme and alpha-1-antichymotrypsin, markers for monocyte-macrophage derived cells. Immunohistochemically, the cells stained for vimentin but not for cytokeratins, desmin, S-100 protein, epithelial membrane antigen, alpha-lactalbumin, lysozyme, alpha-1-antichymotrypsin, alpha-lactalbumin, casein, and heavy and light chain immunoglobulins. The combined findings of light and transmission electron microscopy and immunohistochemistry exclude tumor histogenesis from an epithelial cell, melanocyte, mast cell, plasma cell, Schwann cells, and Merkel cell.