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Fibrosarcoma in infants and children. Application of new techniques.

Fibrosarcomas occurring in infants and young children are intriguing tumors. Although biologically more benign than their counterparts occurring in old patients, they are histologically similar. Microscopically, they fit in one end of a spectrum of fibrous proliferations occurring in the pediatric population. Prompted by recent karyotypic reports of nonrandom gains of chromosomes 8, 11, 17, and 20 in infantile fibrosarcomas, we retrospectively analyzed 12 infantile fibrosarcomas utilizing fluorescence in-situ hybridization (FISH) with chromosome 8-, 11-, 17-, and 20-specific probes. Parallel studies were performed on fibrosarcomas occurring in older children and young adults and also on cellular fibromatoses, myofibromatoses, and fibromatoses. Gains of chromosomes 8, 11, 17, and 20 (in various combinations) were observed in 11 of 12 fibrosarcomas occurring in infants < 2 years of age. Extra copies of chromosomes 17 and 20 were observed in a fibrosarcoma occurring in a 5-year-old child but no abnormalities were detected by FISH in four additional fibrosarcomas occurring in patients aged 6-17 years. One of three cellular fibromatoses was characterized by extra copies of chromosome 8, 11, 17, and 20. Similar findings were not observed in any of the noncellular fibromatoses or in myofibromatoses.

Adolescent↗

In vitro and in vivo interaction between murine fibrosarcoma cells and natural killer cells.

Murine fibrosarcoma cells were examined for sensitivity to killing by natural killer (NK) and natural cytotoxic lymphocytes from mouse spleens. These tumor cell lines were sensitive to killing by effector cells which were nonadherent to plastic or nylon wool, Thy-1 negative, asialo-GM1 negative, and present in the spleens of beige mice, nude mice, and A/J mice, as well as in the spleens of normal syngeneic and allogeneic control mice. This indicates that the cytotoxic effects were due to natural cytotoxic lymphocytes rather than to NK lymphocytes, T-cells, or macrophages. Although the fibrosarcoma cells were not killed in vitro by endogenous NK cells, these tumor cells were able to "cold target" compete for Yac-1 (an NK-sensitive target) killing and to bind to asialo-GM1-positive, nonadherent spleen lymphocytes in a target cell binding assay. This suggests that the fibrosarcoma cells were recognized by NK cells. In addition, these cell lines were killed in a 4-h NK cytotoxicity assay by polyinosinic-polycytidylic acid-activated effector lymphocytes. The interaction between NK cells and the murine fibrosarcoma cells may have in vivo significance. When syngeneic mice were treated with anti-asialo-GM1 serum to eliminate NK activity and then given i.v. injections of the fibrosarcoma cells, many more lung tumors developed than in control animals. The structural basis for the recognition of the murine fibrosarcoma cells by the NK effector cells is not known. However, laminin may be involved. When the fibrosarcoma cells, which have receptors for the laminin molecule, were preincubated with laminin, they were reduced in their ability to compete for the killing of Yac-1 cells by the NK effectors and had reduced capacity to bind to NK cells in a target cell binding assay.

Animals↗

Differential immunoreactivity and Ca2+-dependent degradation of vimentin in human fibroblasts and fibrosarcoma cells.

Immunostaining of normal human fibroblasts with a monoclonal antibody (MAb) (V22AC12) revealed typical cytoplasmic arrays of vimentin filaments in both mitotic and interphase cells. In human A8387 fibrosarcoma cells and SV40-virus-transformed human fibroblasts, the same antibody showed positivity only in mitotic cells and in interphase cells only after treatment of the fixed cells with alkaline phosphatase. Upon immunoblotting with the MAb, an Mr 57,000 vimentin polypeptide was seen in normal fibroblasts. In fibrosarcoma cells the same polypeptide was revealed by this antibody only after treatment with alkaline phosphatase. The Mr 57,000 vimentin polypeptide was a major cytoskeletal protein in both fibroblasts and fibrosarcoma cells. Inclusion of Ca2+ into the cytoskeleton extraction medium brought about a somewhat increased degradation of vimentin in fibroblasts. In fibrosarcoma cells, such treatment caused a quantitative disappearance of the Mr 57,000 protein with a concomitant appearance of 3 distinct, low-molecular-weight degradation products in the detergent-soluble fraction. Another Ca2+-induced change in the polypeptide profile of fibrosarcoma cells was the disappearance of the Mr 240,000 non-erythroid alpha-spectrin and the concomitant appearance of a prominent Mr 140,000 degradation product. Inclusion of proteolysis inhibitors in the Ca2+-supplemented extraction medium inhibited degradation of both vimentin and alpha-spectrin polypeptides. The results suggest differences in the composition of the cytoskeletons of normal fibroblasts and fibrosarcoma cells, manifested in the differential Ca2+-susceptibility of vimentin and non-erythroid alpha-spectrin. Results with MAb V22AC12 suggest that differential phosphorylation of vimentin could account for at least part of this difference.

Antibodies, Monoclonal↗

Fibrosarcoma in pediatric patients: results of the Italian Cooperative Group studies (1979-1995).

BACKGROUND AND OBJECTIVES: Fibrosarcoma is a rare soft tissue sarcoma (STS) that has two peaks of incidence in pediatric patients: one in infants and young children (infantile fibrosarcoma), another in older children ("adult type" fibrosarcoma). The purpose of this study was to describe the clinical features and the treatment results in patients affected by fibrosarcoma enrolled in two consecutive studies run by the STS-Italian Cooperative Group (ICG) between 1979 and 1995. PATIENTS AND METHODS: Twenty-five evaluable patients were grouped according the intergroup rhabdomyosarcoma staging (IRS) system: 12 Gr I, 5 Gr II, 8 Gr III. The cut-off point between the two forms was considered the age of 2 years: 14 patients were affected by infantile and 11 by adult type of fibrosarcoma. The therapeutic guidelines were not strict and not different for the two forms: patients with initial macroscopic excision (Gr I-II) were given IVA or VAC; Gr III had VAC or VAIA and subsequent excision, if feasible. Radiation therapy (RT) was delivered in patients > 3 years with microscopic (42 Gy) and macroscopic (54 Gy) residuals. RESULTS: Thirteen patients are alive without evidence of disease: 10 in first complete remission (CR), 7 Gr I, 1 Gr II, 2 Gr III, 3 in second CR after local relapse (LR) (2 Gr I, 1 Gr II). Two Gr I patients are alive with metastatic relapse. Nine patients died: six of progressive disease (PD) (three Gr II, three Gr III), two because of a second tumor (one Gr I, one Gr III) and one because of other causes (Gr III). One Gr III patient was lost at follow up, 2 years from diagnosis. The 10 years overall survival (OS) is 67.4% and the progression-free survival (PFS) is 52.2%. The OS for patients < 2 years is 78.6% (11 of 14), versus 51% for patients > 2 years (5 of 11). CONCLUSIONS: The complete excision at diagnosis was the treatment of choice and was related to the best outcome. Microscopical residuals were difficult to treat with chemo-radiotherapy in both forms of fibrosarcoma. Neoadjuvant chemotherapy (CT) obtained a partial remission (PR) only in three of eight cases, while no conclusions concerning the efficacy of CT for infantile forms are possible. Patients < 2 years had a better outcome than the older ones: most of them had a tumor on extremities which was excised at diagnosis.

Adolescent↗

Expression of COL1A1-PDGFB fusion transcripts in superficial adult fibrosarcoma suggests a close relationship to dermatofibrosarcoma protuberans.

The diagnosis of fibrosarcoma has become relatively rare since the recognition and definition of certain adult spindle-cell sarcomas, such as monophasic synovial sarcoma, malignant peripheral nerve sheath tumour (MPNST), and malignant fibrous histiocytoma (MFH). Although most adult fibrosarcomas occur within intra- or inter-muscular fibrous tissues, some originate from superficial soft tissues (superficially located adult fibrosarcomas) (SAFs). Recently, the COL1A1-PDGFB chimeric gene resulting from a reciprocal translocation, t(17;22), and/or a supernumerary ring chromosome, r(17;22), has been identified, not only in conventional dermatofibrosarcoma protuberans (DFSP) but also in areas of DFSP with progression to fibrosarcoma (so-called fibrosarcomatous transformation) (FS-DFSP). Since many SAFs are clinically and histologically similar to DFSP or FS-DFSP, this study postulated that the two groups may be interrelated histogenetically. To test this hypothesis, a reverse transcription-polymerase chain reaction (RT-PCR) assay was conducted to determine whether COL1A1-PDGFB fusion transcripts could be detected in six cases of SAF, using archival formalin-fixed, paraffin-embedded tissues. COL1A1-PDGFB fusion transcripts were detected in four of six SAFs, whereas no such fusion transcripts could be amplified in five deep-seated fibrosarcomas, eight congenital/infantile fibrosarcomas or 28 other spindle-cell tumours and tumour-like lesions. These results show that at least some cases of SAF are genetically similar to DFSP and FS-DFSP, suggesting that some SAFs originate from DFSP or involve similar pathogenetic mechanisms.

Adult↗

Purification and characterization of collagens from rat fibrosarcoma induced by 3-methylcholanthrene.

The distribution of various collagen types was studied in rat fibrosarcoma. Collagens extracted from fibrosarcoma tissue were characterized by the criteria of solubility in NaCl, SDS-PAGE, ion exchange chromatography, CNBr peptide mapping and amino acid analysis. Fibrosarcoma was found to produce excess amount of type V, type I trimer and type III collagens; comparatively, type I collagen and total collagen content were noticed to decrease in fibrosarcoma. We observe that the increase in type V collagen content in fibrosarcoma might be due to the enhanced transcription of type V collagen gene. Increased type I trimer collagen in fibrosarcoma might be attributed to the differential expression of alpha 1(I) and alpha 2(I) gene and might also be due to the expression of a different gene for type I trimer collagen.

Animals↗

Immunotherapeutic studies of different clonal lines of herpesvirus-induced fibrosarcoma in a syngeneic rat.

Transformation of White Buffalo rat embryonic cells by dye-light-inactivated herpesvirus type 2 resulted in the development of two clones of transformed cells (G2 and rat fibrosarcoma) with significantly different tumorigenic capabilities. The G2 cell line was initially nontumorigenic, while the rat fibrosarcoma line was very highly tumorigenic in rats. These significant differences in transformed cell clones from the same initial culture offered an opportunity to study aspects of the immunobiology of oncogenicity. The development of fibrosarcomas in immunoincompetent nude mice with the same early passages of the G2 cell line which were nontumorigenic in the immunocompetent rat suggested that immunologic resistance developed more effectively in the competent host against the G2 line than against rat fibrosarcoma cells. Syngeneic rats which were first exposed to the early passage nontumorigenic G2 cells were completely protected against tumor development by the rat fibrosarcoma cell lines. In subsequent in vitro passages of the G2 cell line, it lost its ability to protect against rat fibrosarcoma challenge and gradually became oncogenic in rats. Modification of antigenic exposure, accomplished by treating the G2 cells with cholesteryl hemisuccinate, resulted in an increase in the protection by these cells and a delay in tumor development.

Animals↗

Fibrosarcoma versus cellular fibroma of the ovary: a comparative study of their proliferative activity and chromosome aberrations using MIB-1 immunostaining, DNA flow cytometry, and fluorescence in situ hybridization.

We retrospectively analyzed the proliferative activity and the centromeric copy number of chromosomes 8, 12, and 17 in three cases of fibrosarcoma and eight cases of cellular fibroma of the ovary using MIB-1 immunostaining, DNA flow cytometry, and fluorescence in situ hybridization (FISH) on paraffin-embedded tissue specimens. In our study, both the MIB-1 labeling index (LI) and the proliferative index (% of cells in S + G2 + M phase) in fibrosarcomas were higher than those in cellular fibromas. The FISH analysis demonstrated the sole abnormality of a gain of trisomy 12 cells in all eight cases of cellular fibroma. Both a gain of trisomy 12 cells and a gain of tetrasomy 12 cells were observed in one case of fibrosarcoma. A gain of trisomy 8 cells was observed in all two fibrosarcomas in which signals were detected. By contrast, neither a gain of trisomy 8 cells nor a gain of tetrasomy 12 cells was observed in any of the eight cases of cellular fibroma. Chromosome 17 showed disomy in all eleven cases. On the basis of these findings, a gain of trisomy 8 cells is therefore considered to be an adequately effective marker to distinguish between cellular fibroma and fibrosarcoma of the ovary, and it may also be related to the proliferative activity of fibrosarcoma of the ovary.

Adolescent↗

Infantile and adult fibrosarcomas of the soft tissues.

Histologic sections of 68 soft-tissue sarcomas initially diagnosed as fibrosarcoma were reviewed, and 36 were excluded because of revised diagnosis. The tumors from the remaining 32 patients were analyzed clinicopathologically, and were classifed into two types; the adult type (22 cases) and the infantile type (10 cases). The adult type fibrosarcoma occurred in adults aged 25 to 67 years and consisted of spindle-shaped fibroblastic cells which formed interlacing bundles accompanied by variable amounts of collagen or reticulin fibers. The infantile fibrosarcoma affected children below the age of seven years in this series and was characterized by proliferation of immature fibroblasts forming indistinct bundles, frequently exhibiting areas of an angiosarcoma-like pattern and cavernous blood vessels. The authors expressed the view that infantile fibrosarcoma should be separated from adult fibrosarcoma, because between these two types of fibrosarcoma there were marked differences in the histologic feature as well as in the age, sex and anatomical distributions.

Adult↗

Congenital infantile fibrosarcoma of the thigh in a newborn.

Congenital/infantile fibrosarcoma occurs frequently in the first year of life and differs from fibrosarcoma in adulthood. The clinical course of congenital/infantile fibrosarcoma is more favorable and metastatic spread is rare. While adult fibrosarcomas are common in the thigh, congenital/infantile fibrosarcomas affect chiefly the distal portions of the extremities. Standard treatment is primarily wide surgical excision. Chemotherapy may be given as neoadjuvant or adjuvant treatment in order to avoid the morbidity associated with wide excision. In this case report we present our experience of a newborn affected by congenital/infantile fibrosarcoma of the left thigh.

Antineoplastic Combined Chemotherapy Protocols↗

Cytoskeletal-induced alterations in the adhesion of HT-1080 fibrosarcoma cells to extracellular matrix.

We have investigated the adhesion of the human fibrosarcoma cell line, HT-1080, transfected with glial fibrillary acidic protein (GFAP) to a variety of extracellular matrix macromolecules (ECM) including collagen type IV, laminin, and fibronectin. The GFAP-transfectants demonstrated altered adhesiveness to extracellular matrix substrates when compared to controls. GFAP-positive, heavy metal-induced fibrosarcoma cells were more adherent to plastic and collagen type IV than were the parental or uninduced cells. In contrast, GFAP-positive fibrosarcoma cells were less adherent to laminin- or fibronectin-coated dishes than controls. Time course adhesion studies over 9 days showed that the heavy metal-induced fibrosarcoma cells progressively became more adherent to collagen type IV and less adherent to laminin- or fibronectin-coated dishes than did uninduced cells. However, with the removal of heavy metal from the medium, the HT-1080 fibrosarcoma cells were restored to their original adhesive potential. By phase microscopy, uninduced and induced HT-1080 cells demonstrated different morphological features and remained viable in an anchorage-dependent fashion on collagen type IV as a substrate. By way of contrast, GFAP-induced HT-1080 cells were not particularly viable in monolayer culture and readily detached from laminin as a substrate. The expression of beta1 integrin in GFAP-positive fibrosarcoma cells was decreased following heavy metal induction by Western blot analyses. In contrast, the expression of alpha2 integrin was increased whereas alpha5 integrin was unchanged in HT-1080 cells following the induction of GFAP. Gelatin zymography showed that 72 kDa collagenase was less expressed in GFAP-induced clones than in controls. Our data suggest that the forced expression of the intermediate filament, GFAP, in HT-1080 cells may modulate cell adhesion to different ECM substrates through alterations in expression of integrins.

Blotting, Western↗

[Ultrastructural study of fibrosarcoma].

Ultrastructure of 9 cases of fibrosarcoma was observed and compared with that of fibrous connective tissue of 4 human embryos and 9 cases of spindle cell sarcoma, including 3 each of leiomyosarcoma, neurofibrosarcoma and dermatofibrosarcoma protuberans. Ultrastructurally, fibrosarcoma consisted of well-differentiated fibroblast-like cells, poorly differentiated fibroblast-like cells (embryonic fibroblast-like cells), myofibroblast-like cells and primitive mesenchymal cells. It is suggested that fibrosarcoma may arise from primitive mesenchymal cells which are capable of differentiating into fibroblast and myofibroblast. There were two special cases of fibrosarcoma in this series. One was a congenital fibrosarcoma with ultrastructure resembling adult and the other was a sarcoma of myofibroblast. Diagnosis and differential diagnosis between fibrosarcoma and leiomyosarcoma, neurofibrosarcoma, dermatofibrosarcoma protuberans are discussed.

Adolescent↗

Fibrosarcoma of the nose and the paranasal sinuses.

We report a case of fibrosarcoma of the nose and paranasal sinuses and give a brief review of the literature. Fibrosarcoma of the nose and paranasal sinuses is uncommon, and few cases have been reported to date. Previously these tumors may have been overdiagnosed secondary to inadequate diagnostic procedures. Because histologic diagnosis is difficult, these tumors have been confused with other lesions of the head and neck. Thus, the improvement in diagnostic procedures has significantly reduced the reported incidence of fibrosarcoma. Because histologic diagnosis is difficult, this tumor has often been confused with other lesions of the head and neck. To ensure proper handling of the tissue, the pathologist should be informed if fibrosarcoma is suspected. It may be necessary to use electron microscopy or staining techniques such as immunoperoxidase stains to distinguish fibrosarcoma from other lesions. Unfortunately, the early signs and symptoms of the tumor are vague and sometimes misleading. Thus, at the patient's initial visit, it is important that the physician consider the possibility of fibrosarcoma.

Aged↗

Fibrosarcoma versus fibromatoses and cellular nodular fasciitis. A comparative study of their proliferative activity using proliferating cell nuclear antigen, DNA flow cytometry, and p53.

We analyzed the proliferative activities, immunoreactivity of the p53 protein, and aneuploidy in patients with benign and malignant fibrous lesions, including 19 with nodular fasciitis (cellular type) (6-88 years old, mean 42.9), 11 with abdominal fibromatoses (22-74 years old, mean 37.9), 13 with extraabdominal fibromatoses (2-38 years old, mean 19.5), and 23 with fibrosarcomas (adult type: 16-71 years old, mean 47.3; infantile type: 3 months to 9 years, mean 2.9) using immunohistochemistry to determine proliferating cell nuclear antigen (PC10) and p53 protein (CM1) as well as performing DNA flow cytometry. The proliferating cell nuclear antigen (PCNA) score was measured as the ratio of PCNA-positive nuclear size/total nuclear size determined by an image analysis computer system. The distribution pattern of the PCNA-positive cells was uneven in each instance of nodular fasciitis, in contrast to the distribution in abdominal fibromatosis, extraabdominal fibromatosis, and fibrosarcoma. Both fibrosarcoma (28.4 +/- 20.0) and nodular fasciitis (33.6 +/- 20.9) exhibited a larger value and a greater variation in the PCNA score than did either abdominal (13.5 +/- 14.5) or extraabdominal fibromatosis (19.9 +/- 21.5). Abdominal fibromatosis exhibited a smaller value and less variation in the score. In short, the PCNA score did not correlate with the malignant potential. The proliferative index (S + G2 + M fraction) in fibrosarcoma was significantly higher than in either nodular fasciitis or abdominal fibromatosis. Aneuploidy was detected in five cases (26%) of fibrosarcoma, while six (26%) fibrosarcomas showed p53 positivity. Furthermore, p53-positive patients had a worse survival (0.01 < p < 0.05), and p53 positivity correlated with the proliferative index (p < 0.01). In conclusion, the PCNA score simply indicates the proliferative activity independent of malignant potential. On the other hand, p53 positivity, proliferative index, and aneuploidy are all indicators of malignant potential in fibroblastic lesions, and p53 positivity may reflect a poor prognosis.

Adolescent↗

Ameloblastic fibrosarcoma of the jaws. A clinicopathologic and DNA analysis of five cases and review of the literature with discussion of its relationship to ameloblastic fibroma.

Ameloblastic fibrosarcoma, the malignant counterpart of the ameloblastic fibroma, is a rare odontogenic tumor characterized by benign epithelium and a malignant fibrous stroma. We have compared nuclear DNA content of five ameloblastic fibrosarcomas and three ameloblastic fibromas by image analysis. The three ameloblastic fibromas were diploid, whereas 1 of 5 ameloblastic fibrosarcomas was aneuploid. There was no correlation with histologic grade and aneuploidy. These five new cases were also added to a review of the literature, bringing the total cases of reported ameloblastic fibrosarcomas to 51. The ameloblastic fibrosarcoma occurs at a later age (mean, 27.5 years) compared with reported ameloblastic fibromas (mean, 14.6 to 22 years), which supports a step-wise malignant transformation. There was histologic documentation that 44% of ameloblastic fibrosarcomas developed in ameloblastic fibromas. In view of this data and of the reported cumulative recurrence rate of 18.3% for ameloblastic fibroma, it is recommended that ameloblastic fibromas be treated with complete surgical excision and long-term follow up rather than simple curettage or enucleation.

Adolescent↗

Inflammatory fibrosarcoma: update, reappraisal, and perspective on its place in the spectrum of inflammatory myofibroblastic tumors.

Inflammatory fibrosarcoma (commonly referred to as inflammatory myofibroblastic tumor) has become increasingly recognized as part of a spectrum of inflammatory myofibroblastic proliferations. It is a potentially locally aggressive myofibroblastic tumor that occurs predominantly in the mesentery of children and young adults. No reliable morphological parameters have been identified that predict prognosis. We evaluated the ultrastructural and immunophenotypic features of 16 cases of inflammatory fibrosarcoma and studied Ki67 (MIB1), PCNA, bcl-2, and p53 in an effort to identify prognostic markers. p53 was not detected immunohistochemically in any case. None of the markers were found to correlate with local recurrences, metastases, or tumor deaths. Low proliferative activity (Ki67 < 10%) was seen in all cases. A characteristic immunophenotype was reconfirmed in which lesional myofibroblasts stained for vimentin, alpha-smooth muscle actin, cytokeratins, and rarely desmin. Ultrastructural studies of seven cases confirmed the presence of a fibroblastic-myofibroblastic spectrum. Because inflammatory myofibroblastic tumor-inflammatory fibrosarcoma is associated with systemic symptoms, polymerase chain reaction studies for Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were performed in 12 cases. Evaluable results in nine cases did not show evidence of either virus. The results of this study indicate that inflammatory fibrosarcoma has a low proliferative activity, which is in keeping with the impression that this is a low-grade sarcoma; that myofibroblasts can participate in true neoplasia; and that EBV and CMV do not play a role in the pathogenesis of inflammatory fibrosarcoma. The variable phenotype of the myofibroblast and its role in reactive and neoplastic processes are discussed. A perspective on the position of inflammatory fibrosarcoma in the spectrum of inflammatory myofibroblastic tumors is also given in light of the current study and the literature.

Adolescent↗

Gains of 12q are the most frequent genomic imbalances in adult fibrosarcoma and are correlated with a poor outcome.

Comparative genomic hybridization was used to analyze 41 adult fibrosarcomas from 34 patients. Thirty-one patients showed in their tumors DNA sequence copy number changes (mean 11, range 3-25). The minimal common regions for the most frequent gains were narrowed down to 12q21 (18 cases); 12q14-q15 and 14q22 (16 cases each); 4q22, 7q31, and 14q23-q24 (15 cases each); and 4q21, 4q23-q24, 8q22, and 12q22 (14 cases each). Twenty-five high-level amplifications were observed in 12 samples. 12q21 and 18p were affected three times each; and 1p21, 4q31.3, 7p21, 12q14-q15, Xp22.1-p22.2, and Xq22-q23 two times each. Losses were less frequent than gains. Early stages of adult fibrosarcomas were characterized by frequent gains of chromosomes 2, 4q, and 14q, whereas gains of chromosomes 7 and 8q were associated with progression. Gains of 12q were frequent in all of the developmental steps of this soft-tissue sarcoma. By investigation of several tumors of the same patient, a number of corresponding changes were always detected. Adult fibrosarcomas from patients who died during the observation time showed statistically significant more frequent gains of 8q, 12q, 13q, and 15q compared to the fibrosarcomas of patients who are alive. Gains and high-level amplifications of 12q14-q22, which were the most frequent genomic imbalances, partly reflected an MDM2 amplification, indicating the importance of this region in the tumorigenesis of sarcomas. In adult fibrosarcomas, a gain of 12q22 correlated significantly (P = 0.028) with a poor overall survival rate.

Abdominal Neoplasms↗

Inhibition of syngeneic fibrosarcoma growth by lymphocytes sensitized on tumor-cell monolayers in the presence of the thymic humoral factor.

The present experiments were performed to investigate the possibility of inhibiting tumor growth in vivo with syngeneic lymphocytes sensitized in vitro on monolayers of the tumor under test, and to study the effect of a thymic humoral factor (THF) in this sensitization process. Monolayers of fibrosarcoma cells were used to sensitize spleen cells from syngeneic donors against the tumor. Such sensitized lymphocytes manifested cytotoxic activity against cells fo the fibrosarcoma in a microassay measuring tumor-cell detachment. However, when the sensitized lymphocytes were mixed with the fibrosarcoma cells and injected into syngeneic mice, enhanced tumor growth was observed in vivo. Addition of thymic humoral factor to the cultures during sensitization resulted in increased cytotoxic activity by the lymphocytes in vitro and a reduction in the tumor enhancement caused by these cells when injected in vivo. Enhanced tumor growth occured when activated lymphocytes of allogeneic as well as syngeneic origin were injected together with the fibrosarcoma cells. Enhancement, which was already apparent when the spleen cells had been sensitized for 24 h, could be circumvented by separate administration of lymphocytes and tumor cells. Syngeneic lymphocytes injected systemically after sensitization for 5 days exerted anti-tumor reactivity against the fibrosarcoma grafted in the foot-pad of syngeneic mice. Tumor growth was further inhibited by systemic injection of lymphocytes which had been sensitized in the presence of the thymic humoral factor.

Animals↗