Analysis of the close relationship between human astrocytoma-specific antigens detected by murine monoclonal antibodies and c-kit proto-oncogene product

Tyrosine-specific phosphorylated proteins found exclusively on the cell surface of human astrocytomas were previously identified with murine monoclonal antibodies, designated as GA-17, GB-4 and GC-3. The purpose of this study was to further characterize the antigens and investigate the relationship between them and c-kit protooncogene product. We demonstrated that the antigens had protein kinase activity. Moreover, GA-17 reacted with c-kit protein expressed on the membrane of A172 human glioblastoma cells.

Neuroectodermal tumors of the peripheral and the central nervous system share neuroendocrine N-CAM-related antigens with small cell lung carcinomas

The current study describes the presence of neuroendocrine antigens of peripheral and central neural tumors using eight monoclonal antibodies raised to small cell lung carcinoma (SCLC), which recognize "neural/neuroendocrine" or "neural" antigens, as defined by their reaction pattern in normal tissues and tumors. At least five of them recognize different epitopes of the neural cell adhesion molecule (N-CAM). It was found that all of 12 neuroblastomas, 2 ganglioneuroblastomas and 4 ganglioneuromas as well as 23 central primitive neuroectodermal tumors, 13 astrocytomas and 4 ependymomas share "neural/neuroendocrine" antigens (as defined by the anti-N-CAM antibodies Moc-1, -21, -32, -52 and -191) with SCLC. The "neural/neuroendocrine" antigen defined by Moc-171 was also found in all peripheral tumors, but only in further differentiated central tumors. Non-N-CAM related "neural" antigens (as defined by Moc-51 and -172) were found only in better-differentiated peripheral and central tumors, but they could be demonstrated in all three medulloblastoma cell lines studied. In addition, the antigen defined by Moc-51 was demonstrated in an immunoblot of a neuroblastoma cell line. Antibodies recognizing "epithelial" antigens of SCLC and other epithelia and their tumors (Moc-31 and -181) were non-reactive. It was concluded that these findings give further support for a relation between neural and neuroendocrine tumors and that some of the antibodies may be useful for the detection of differentiation in neural tumors. Antibodies with an "epithelial" recognition pattern may serve to distinguish neural from neuroendocrine tumors.

Serological analysis of tumor antigens in malignant glioma patients

Sera from 27 malignant glioma patients were tested for antibodies to surface antigens of cultured human glioma cells using enzyme-linked immunosorbent assay. Average antibody titer for glioma cell lines was 0.558 +/- 0.123, which was significantly higher than in the normal control group (0.165 +/- 0.082). Surprisingly, average antibody titer for autologous glioma cells was low (0.207 +/- 0.154) in these patients. The results suggest that various surface antigens in glioma cells include specific autologous antigens, antigens associated with gliomas, and common antigens present on cultured normal and malignant cells. These analyses are important in the evaluation of monoclonal antibodies and explanation of escape mechanisms.

[Quantitative study on DNA content and nucleolar organiser regions in astrocytoma]

Forty-one astrocytomas of different grades were studied by means of image analysis technique for measuring DNA content in situ, and in 28 tumors the numbers of nucleolar organiser region (NORs) associated proteins were also determined, and 12 cases of astrocytoma in frontal lobes were followed up. The results showed that the distribution of DNA content in grade I astrocytoma was 2C-4C, the peak values of grade I astrocytoma was 2C; while for grade II, 3C-4C and hypertetraploid. DNA contents of grade III and IV astrocytomas were much higher, their histograms were dispersed with many peaks, the peak values were aneuploid and heteroploid. The data confirm that heteroploid and aneuploid are the marks of malignancy. The grade II astrocytoma which possesses these features has a tendency to higher malignancy. Twenty-eight astrocytomas were stained by Argyrophil (Ag-NOR) for NOR associated proteins. The largest numbers of Ag-NORs were seen in grades III and IV astrocytoma (mean 11.71), and their Ag-NORs were irregular. Grade I astrocytoma possessed the fewest Ag-NORs (mean 6.5) which were small and uniform. The results suggest that the number of Ag-NORs is associated with the differentiation. The prognosis is significantly correlated with the numbers of Ag-NORs and the contents of DNA in astrocytomas.

IL-1 and TNF-alpha induction of IL-8 and monocyte chemotactic and activating factor (MCAF) mRNA expression in a human astrocytoma cell line

In order to elucidate the role of inflammatory cytokines in the central nervous system (CNS), we examined whether IL and TNF-alpha induce cells in the CNS to produce two newly identified leucocyte chemo-attractants, IL-8 and monocyte chemotactic and activating factor (MCAF). Several human astrocytoma and glioblastoma cell lines expressed high levels of IL-8 and MCAF mRNA in vitro upon stimulation with IL-1 and TNF-alpha. In particular, an astrocytoma cell line U373MG subclone responded markedly to IL-1 with high expression levels of IL-8 and MCAF mRNA as well as IL-6 mRNA. Both IL-8 and MCAF mRNA expression depended on the dose of IL-1 and appeared as early as 30 min to 1 hr after IL-1 stimulation, confirming that these are early inducible genes. The production of IL-8 and MCAF in the U373MG cell culture supernatants was confirmed by a competitive radioimmunoassay (RIA) as well as chemotactic activities on human neutrophils and monocytes. IL-1-induced IL-8 and MCAF mRNA expression appeared to occur at least at the transcriptional level as revealed by a nuclear run-off assay. Moreover, IL-1 treatment increased the half-life of IL-8 and MCAF mRNA markedly, suggesting that increased mRNA stability was also responsible for the enhanced gene transcription. These data suggest that IL-1 and TNF-alpha induce astrocytes to produce IL-8 and MCAF transcriptionally and post-transcriptionally, both of which may be responsible for leucocytosis seen in inflammation of the CNS.

[Sensitivity of human glial tumor cells of different grade of anaplasia to lysis due to natural killers depending on some characteristics of the glycoprotein structure of tumor cell membranes]

A study is presented of the sensitivity of freshly isolated cells (13 cases) to lysis due to natural killers (NK) depending on their malignancy grade and degree of their membrane sialization. The diagnoses were verified histologically (I-II grade gliomas-4 cases, grade III gliomas-3 cases, grade IV gliomas-6 cases). It was established that grade IV gliomas were most sensitive to NK-lysis. Treatment of tumor cells with neuraminidase increased the sensitivity to NK-lysis of grade I-III glioma cells and did not influence the sensitivity of grade IV gliomas. It is suggested that glycoprotein oligosaccharides of glial tumour cell membranes may play the role of target structures for lymphocytes-killers.

[Second solid tumors in childhood. Review based on three cases]

As children with cancer survive longer, the incidence of second malignant neoplasms has increased considerably. We describe here three cases of second solid tumors after 12, 8 and 2 years of initial diagnosis of cancer: one osteosarcoma of left maxilla in a previously treated child with bilateral retinoblastoma, a temporal astrocytoma associated with acute lymphoblastic leukemia and a glioblastoma multiforme in a girl with neurofibromatosis de Von Recklinghausen, after Non Hodgkin lymphoma, respectively. We review the literature about the influence of genetic, immunologic and therapeutic factors involved in the appearance of these second tumors.

Cytological characteristics of human glioma-infiltrating lymphocytes stimulated with recombinant interleukin 2 and an anti-CD3 antibody

Tumor-infiltrating lymphocytes (TIL) were generated from 10 glioma specimens by using recombinant interleukin-2 and an anti-CD3 antibody (CD3 + TILs). We obtained more than 1 x 10(9) cells in 5 cases, more than 5 x 10(8) cells in 2 cases, and about 1 x 10(8) cells in 3 cases during three weeks of incubation from small specimens ranging in weight from 0.5 to 2.0 g. In 4 cases, TILs were expanded following stimulation with only rIL-2 (CD3-TILs). The growth rate of CD3-TILs was less than that of CD3 + TILs. Cytotoxicity of CD3 + TILs was lower than that of lymphokine-activated killer (LAK) cells in a standard 4h 51Cr release assay. Cold target inhibition was undertaken in three cases and specific cytotoxicity could be shown in only one case. CD3 + TILs mainly consisted of CD3-positive cells, ranging from 63.2 to 99.9%. The ratio of CD4-positive cells to CD8-positive cells was not constant. The expression of Leu 7 and CD16 was low. The present study did not confirm previous findings that TILs were more tumor-selective and potent than LAK cells. Furthermore, the results on in vitro antitumor activity of those cells were not necessarily consistent with the results on their clinical activity. Further careful work is necessary on the preparation of immunocytes and the subsequent adoptive immunotherapy.

The cycling pool of cells within human brain tumors: in situ cytokinetics using the monoclonal antibody Ki-67

Brain tumor growth results from the relative proportion of cells contained in three populations: a) cycling/proliferative; b) quiescent (GO)/static, and c) terminally differentiated/dying. The cycling compartment can be detected by the mouse monoclonal Ki-67 antibody, an available, rapid, safe, sensitive, and specific method for immunostaining of proliferative cells. We report the Ki-67 labeling index (LI) in 48 brain tumors. Malignant brain tumors have elevated LIs, ranging from 6.0% to 56.9%: anaplastic astrocytoma, 8.0 +/- 7.3; glioblastoma multiforme, 10.1 +/- 4.2; germinoma, 11.7; medulloblastoma, 13.1 +/- 6.6; metastases, 40.3 +/- 13.1. By contrast, slow-growing tumors showed lower values (P less than .001), approaching 1%: acoustic schwannoma, 0.4 +/- 0.6; pituitary adenoma, 1.3 +/- 1.9; meningioma, 1.2 +/- 1.2; low-grade astrocytoma, less than 1; pilocytic astrocytoma, 5.6. Human brain tumors can therefore be ranked according to the percentage of cycling cells with the acoustic schwannoma among the least proliferative and the metastatic carcinoma among the most proliferative. Within a given histotype, the Ki-67 LI may have prognostic and therapeutic implications for the individual patient. Already important for neuro-oncology research, the Ki-67 labeling index should be added to the armamentarium of the clinical neuropathologist to complement the standard histopathologic diagnosis with a cytokinetic analysis of cellular proliferation.

[Mouse fetal brain specific protein "GP68" is expressed in human tumor cells]

It is well known that some fetal antigens are expressed in malignant tumor cells. Likewise, brain tumors, especially histologically malignant cases, may have any antigenic relationships with fetal brain. So, we investigated the relationship by immunohistochemical technique, utilizing a polyclonal antibody to mouse fetal stage-specific polypeptide "GP68". We prepared GP68 from homogenate of head part of embryos at the 14th day of gestation mice by RCA-1 agarose column chromatography. And immunized it to Japanese white rabbits and the titer was measured by enzyme-linked immunosorbent assay. We analyzed operatively resected brain tumors and autopsy brain tissues. Frozen tissues were fixed in cold acetone and immunostained with anti-GP68 serum according to biotin-streptavidin peroxidase method. Remained tissues were homogenized in Laemmli's sample buffer and electrophoresed. The proteins were transferred to nitrocellulose membrane and immunostained with anti-GP68. Normal brain tissues were not positively stained, except for capillary endothelium which showed a weak staining. On the other hand, brain tumors of neuroectodermal origin were positively stained in varying degrees, and other tumors were negative. It is especially noteworthy that, in astrocytoma cases, there exists a definite correlation between the intensity of stain and the degree of histological malignancy. Immunoblot studies demonstrated a very weak band at 68 KD in normal brain and meningioma. In contrast, very strong band at the same position was seen in malignant astrocytomas. These results suggested that in brain tumors, especially those of neuroectodermal origin, GP68 antigen is expressed and the degree of expression is related to their histological malignancy. So this fetal antigen may be useful for evaluation of biological malignancy of gliomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody-mediated tumor cytotoxicity of microglia

The status of microglial cells as potent effector cells in antibody-mediated tumor cytotoxicity (ADCC) could be established. Microglia (greater than or equal to 99.9% pure) derived from brain cortices of newborn mice were shown to lyse human tumor cell lines expressing different levels of epidermal growth factor (EGF) receptors in the presence of MAb 425, a monoclonal murine anti-primate EGF receptor antibody. MAb 425 mediates microglial ADCC (MiADCC) at concentrations as low as 10(-11) M. Antibody ligands binding unilaterally to either EGF receptors on target cells or Fc receptors on microglia have little effect on MiADCC. At 10(-10) M MAb 425, a 10(3)-fold excess of MAb 425 F(ab')2 fragments or irrelevant antibodies of identical isotype did not block MAb-425-induced MiADCC. Formation of effector-target cell contacts seems to be critical for MiADCC and MiADCC could not be inhibited by anti-tumor necrosis factor-alpha antibodies. In addition to its stimulatory effect on MiADCC, MAb 425 bound to EGF receptors exerted a microgliotrophic effect. Factor(s) derived from astrocytes enhance MiADCC.

Cell proliferation in serial biopsies through human malignant brain tumours: measurement using Ki67 antibody labelling

Cell proliferation was assessed in brain tumours using the monoclonal antibody Ki67 which recognizes a nuclear antigen expressed by proliferating cells. Using a novel stereotactic biopsy procedure, serial 1 cm biopsies were taken along a trajectory through six malignant brain tumours. Specimens were also obtained from 10 other brain tumours during conventional surgery. The percentage of Ki67 positive cells was determined as a fraction of the total number of tumour cells present. The Ki67 index for anaplastic astrocytomas and glioblastomas was significantly higher (Ki67 index range 11-18%) than that for benign or low grade tumours. Significant variation in proliferation was measured along the biopsy track through individual tumours (e.g. 0-12.3%) which correlated well with histological appearance. The Ki67 indices of normal brain were very low. In general the Ki67 indices increased with increasing histological grade and also appear to be a useful indicator of the active tumour volume and margin. This method provides spatial information about tumour proliferation which may be used to decide between different treatments and relate to prognosis.

Monocyte tumoricidal activity and tumor necrosis factor production in patients with malignant brain tumors

Monocyte-mediated tumoricidal activity, tumor necrosis factor alpha (TNF alpha) secretion and gene expression were examined in astrocytoma patients, patients with other types of brain tumors (primary or metastatic), and normal individuals. The spontaneous monocyte-mediated tumoricidal activity of either patient group against an astrocytoma cell line was significantly greater than normal. There was no difference between patient groups. When monocytes were stimulated with lipopolysaccharide in vitro, tumoricidal activity increased in all patient groups. Patient monocyte activity tested shortly (48 h) after surgery was not different from that before surgery. Both spontaneous and stimulated monocyte cytocidal activities were tumor-cell-restricted: melanoma and astrocytoma cells were equally susceptible but non-neoplastic glial cells were not affected. Examination of monocyte TNF alpha secretion and mRNA expression indicated that patient activity was comparable to or greater than normal. These results demonstrate that, despite steroid therapy, circulating monocytes in astrocytoma and other brain tumor patients retain intact functional activity.

Factor analysis of the immunophenotypes of astrocytomas and malignant gliomas: correlations with tumor grade and patient survival

Our previous investigations correlated the degree of cytogenetic and immunophenotypic heterogeneity of cultured normal glia, astrocytomas and malignant gliomas. The possible significance was suggested by the statistical correlation of individual antigens with diagnosis and patient survival. The present study has established the patterns of covariation of titers of monoclonal antibody reactivity with a panel of cell surface antigens among normal glia (8), astrocytomas (4), anaplastic astrocytomas (12), mixed malignant gliomas (8) and glioblastomas (21). A mean aggregate titer across 43 antigens was computed for each culture and then subtracted from the observed individual titers. Factor analysis was performed to determine a small number of Factors, derived as the weighted average of the 43 mean-adjusted antigens, which accounted for a significant proportion of the covariation of immunophenotypic expression in the sample of 53 cultures. Clusters of antigens were found to independently segregate in their deviation from the aggregate phenotype. Adjusting for age and diagnosis, Factors 1 and 4 correlated with patient survival among recurrent and primary neoplasms, respectively. Factor 2 additionally discriminated between primary and recurrent gliomas. Factor 3 was associated with age at diagnosis. Factors 1 and 2 correlated with the histopathologic grade of glial tumor. Scatter plots of Factor 1 vs. 2 revealed the minimal immunophenotypic diversity of the normal glia. Astrocytomas were similar but not identical. Progressive divergence was evident between the immunophenotypes of anaplastic astrocytomas, mixed gliomas and glioblastomas. These data suggest that qualitative and quantitative differences in antigenic heterogeneity may identify stages in glial tumor progression.(ABSTRACT TRUNCATED AT 250 WORDS)

[Lymphocyte subpopulations and their functional activity in patients with brain tumors]

The authors studied a complex of immunological indices in 69 patients with brain tumours in the pre- and postoperative period. It is shown that in patients with benign brain tumours, preoperative care and surgical intervention largely alter the functional activity of T and B-lymphocytes while patients with malignant tumours of the brain revealed less pronounced changes of quantitative indices of definite subpopulations of lymphocytes against the background of marked reduction of their functional activity. The necessity is emphasized of complex evaluation of immunological indices in patients with brain tumours.

Immunophenotyping of childhood astrocytomas with a library of monoclonal antibodies

Immunophenotype (IP) analysis of 14 childhood glial tumors was performed with a library of 16 monoclonal antibodies (MAbs) using biotin-streptavidin-alkaline phosphatase immunohistochemical detection technique. Presence of glial or neuronal differentiated cells within the tumors was evaluated with MAbs against cell-lineage-specific markers: high-, medium- and low-molecular-weight neurofilament protein (NFP) and glial fibrillary acidic protein (GFAP). Intense expression of GFAP was demonstrated in 14/14 astrocytomas. The three NFs were detected in 10-50% of the cells in 6/14 cases. The pan-neuro-ectodermal antigen defined by MAb UJ 13/A was present in 7/14 astrocytomas on more than 10% of the cells. Thy-1 was expressed in 14/14 tumors on more than 50% of their cells. The GQ ganglioside antigen detected by MAB A2B5, was found in 12/14 tumors. Shared antigens exist among morphologically benign and malignant glial tumor cells and leukocytes detectable with the following four MAbs: Thy-1, PI 153/3, UJ 308 and anti-HLe, common leukocyte antigen (CLA). CLA-expressing cells were demonstrated in 8/12 astrocytomas, and in 4/12 cases more than 90% of the cells were positive. We have shown that cells within childhood astrocytomas can express neuronal IP. The most common expressed phenotype for glial tumors was: GFAP+, Thy-1+, A2B5+, UJ 167.11+, UJ 223.8+, NF (H,M)+, UJ 13/A+, UJ 127.11-, and NF (L)-.

Immunohistochemical analysis of the A4 and AO10 (gp110) cell-surface antigens of human astrocytoma

The A4 and AO10 (110 kd glycoprotein) cell-surface antigens are biochemically distinct markers of cultured human astrocytomas that are expressed by only a limited number of other cultured cell types. To further characterize these two antigens, the authors used immunohistochemical methods to determine their expression in normal human tissues, astrocytomas, and over 100 tumors of other histologic types. They found that A4 is expressed 1) throughout the central (CNS), but not peripheral nervous system (PNS); 2) in smooth muscle and a small number of epithelial tissues; and 3) in reactive glia and in astrocytomas, but not in most tumors of other histologic types. In contrast, the AO10 antigen is expressed 1) in a small subset of CNS neurons, but not in astrocytes, PNS neurons, or other normal tissues; 2) in astrocytomas and reactive glia; and 3) in some additional neuroectodermal tumors, but not melanomas, carcinomas, or sarcomas. These findings show that A4 and AO10 are restricted markers for human astrocytomas in vivo. Furthermore, the antigens show distinct patterns of expression in normal human CNS but appear to be coordinately expressed in astrocytomas and astrocytoma-derived cell lines.

Cross-reactivity of monoclonal antibody Leu-19 with some neuroectodermal and other non-immune tissues

Leu-19 antigen is a 200-220 kDa surface glycoprotein, initially detected on natural killer (NK) cells exhibiting non-major histocompatibility complex-restricted cytotoxicity. Using a monoclonal antibody (mAb) directed against the Leu-19 molecule, we were unable to identify NK cells immunohistologically in cryostat sections of neuroectodermal tumors. Instead, mAb Leu-19 cross-reacted with the surfaces of the tumor cells, except for melanomas. It stained mesodermal tumor cells less intensely and did not stain those of carcinoma metastases. In three plasmacytomas, cells were observed, most likely NK cells, which extend Leu-19-positive cell processes towards to the unstained tumor cells. Furthermore, the Leu-19 antigen was identified on physiological tissues, especially on all neuroendocrine cells analyzed. The cross-reactions observed with Leu-19 mAb were confirmed using mAb NKH-1, which is also directed against the Leu-19 molecule. Thus, the expression of Leu-19 on neuroectodermal cells is another example of antigen sharing between specialized immune cells and the nervous system.

Molecular markers of primitive neuroectodermal tumors and other pediatric central nervous system tumors. Monoclonal antibodies to neuronal and glial antigens distinguish subsets of primitive neuroectodermal tumors

Seventy-one tumors of the central nervous system in children were studied immunohistologically. Thirty-seven were classified histologically as PNETs, of which 35 were located in the cerebellum (medulloblastomas), one in the cerebrum, and one in the spinal cord. The 34 non-PNETs included five ependymomas, seven gangliogliomas, 15 astrocytomas, and seven tumors of other histology. We used monoclonal antibodies specific for neurofilament (NF) triplet proteins, for microtubule associated protein 2 and tau protein and for glial fibrillary acidic protein (GFAP) and myelin basic protein. In addition, a monoclonal antibody to epithelial membrane antigen was applied. The presence or absence of these antigens defined four major groups of PNETs: 1) PNETs not otherwise specified (10 cases), 2) PNETs with neuronal differentiation (eight cases), 3) PNETs with astrocytic differentiation (six cases), and 4) PNETs with both neuronal and astrocytic differentiation (12 cases). One case showed ependymal differentiation. The pattern of expression of NF isoforms in PNETs was reminiscent of that seen during normal mammalian development, such that phosphorylated NF-H was only present in combination with NF-M and NF-L. Among the other central nervous system tumors, all astrocytomas and gangliogliomas were positive for GFAP, and the gangliogliomas also expressed all NF isoforms. Three atypical teratoid tumors and two rhabdoid tumors showed strong positivity for epithelial membrane antigen and also for GFAP. We conclude that the differentiation antigens described here serve to distinguish PNETs from other pediatric central nervous system tumors and to identify subsets of PNETs. Accordingly, PNETs represent a heterogeneous group of pediatric brain tumors capable of neuronal and glial differentiation.

Immunophenotypic differences between normal glia, astrocytomas and malignant gliomas: correlations with karyotype, natural history and survival

The karyotypic and antigenic phenotypes of early passage normal and malignant glial cultures were correlated in vitro. Astrocytomas (4) were distinguished from the normal glia (8) by a mixed near-diploid karyotype and anchorage-independent growth. Malignant gliomas (41) demonstrated cytogenetic abnormalities ranging from mixed normal G- and Q-banded and near-diploid cultures, through mixed near-diploid/hyperdiploid to predominantly hyperdiploid stem-lines. This correlated with the differential expression of certain antigens and established qualitative antigenic differences from normal glia. Associations were found between histopathologic grade of glial neoplasm and the expression of antigens 5.1H11 (p = 0.0002), CNT/11 (p = 0.001), CNT/10 (p = 0.004), CAT301 (p = 0.014), M111 (p = 0.024), and L101 (p = 0.044). An ominous association was demonstrated between the duration of clinical survival and the expression of antigens 5.1H11 (p = 0.0007), CNT/10 (p = 0.027) and B2.6 (p = 0.038). Correcting for diagnosis and age, multivariate analysis demonstrated that HLA-DR (p = 0.050) and 5.1H11 (p = 0.069) were unfavorably correlated with patient survival. This suggests the application of the in vitro immunophenotype for its predictive utility, as well as a novel method of selection of tumor-associated antigens for monoclonal antibody-mediated immunotherapy.

Antigenic heterogeneity of human brain tumors defined by monoclonal antibodies

The antigenic profiles of human gliomas and in vitro established cell lines were investigated using the monoclonal antibodies (MABs) MUC 8-22 and MUC 2-63. The reactivity with tissue samples and cytospin preparations obtained from 45 brain tumors was estimated by the indirect immunoperoxidase technique. In addition, computer-assisted cytofluorometry was used to quantify the intensity and distribution of antibody-binding. Various degrees of antibody-binding among and within gliomas and glioma-derived cell lines were observed. The data show that a variable percentage of cells are not labeled with the employed MABs. The spectrum of reactivity of the selected antibodies was independent of the histological grading of gliomas. However, there were significant differences in various stages of subcultivation of glioma lines. In most cases, the heterogeneity of antigen expression decreased during successive in vitro propagation of glioma cells. The extent of variation in staining intensity values differed within cell populations and reflected the antigenic heterogeneity of human brain tumors. The findings presented here suggest that the use of MABs which recognize glioma-associated antigens facilitates the objective analysis of brain tumors and is of potential value for immunohistochemical application in surgical neuropathology.

Phagocytosis by neoplastic astrocytes

Cytoplasmic accumulation of granules of hemosiderin was observed in neoplastic astrocytes related to gliomas in two patients. The first patient was a 61-year-old man who had mixed oligodendroglioma and astrocytoma of the right frontal lobe of the brain. The second patient was a 17-year-old girl who had hypothalamic astrocytoma. Granules of hemosiderin had accumulated within the cytoplasm of astrocytes in both cases. In case 2, there was also an accumulation of hemosiderin in other phagocytes. The astrocytic nature of the hemosiderin-laden cells was confirmed by immunohistochemical localization of glial fibrillary acidic protein within the cytoplasm. The term "phagocytosis" was employed because of accumulation within astrocytic perikaryon of particulate material. Review of the literature discloses that various neuroepithelial derivatives such as choroidal epithelial cells, astrocytes, neurons, and ependymal cells can perform phagocytic function as revealed by accumulation of granules of hemosiderin within their cytoplasm but this finding has seldom been described.

The effect of fetal irradiation on the growth of postnatally xenotransplanted tumour cells

Exposure of the mouse fetus (NMRI-strain) to 1.0 Gy X-irradiation has a marked effect on postnatally xenotransplanted glioma cells. In comparison to non-irradiated animals, irradiation on gestation day 14 resulted in: (a) a significantly higher rate of animals which failed to develop visible tumours growing from the inoculum; (b) a significant inhibition of the growth rate of solid gliomas; (c) a pronounced granulocytic and mast cell infiltration, and tissue necrosis, in the invading gliomas. The results suggest that irradiation in prenatal life exerts an amplifying effect on the antitumour response in postnatal life.

[Humoral and cellular immunity in patients with left- and right-sided intracerebral tumors]

The authors compared the values of the immune status of patients with glial brain tumor of grade III-IV anaplasia in the left and right side in the preoperative period. In patients with the tumor in the right hemisphere, in the frontotemporal region in particular, the absolute number of rosette-forming cells in peripheral blood and the blast-transformation activity of lymphocytes in response to phytohemagglutinin were reduced significantly (p less than 0.05) as compared to the values in patients with the tumor on the left side. The number of B-lymphocytes and the blood immunoglobulin level were not changed. The possible mechanisms of the revealed differences are discussed with due account of data on immunogenesis regulation by the left hemisphere.

The addition of exogenous gangliosides to cultured human cells results in the cell type-specific expression of novel surface antigens by a biosynthetic process

After the observation that human mAb 32-27M reacts only with melanoma and astrocytoma cells cultured in the presence of fetal bovine serum, a novel pathway for the uptake of exogenous gangliosides, their further biosynthesis, and expression at the cell surface as novel Ag has been elucidated. The addition of fetal bovine serum to melanoma and astrocytoma cells growing in synthetic medium (insulin-transferrin-selenium) resulted in reactivity with Ab32-27M. As antibody 32-27M detects N-glycolylneuraminic acid (NeuGc)-containing gangliosides, the effect of adding a number of different gangliosides to melanoma and astrocytoma cells cultured in the synthetic medium was studied. Only the addition of NeuGc-GM3 resulted in the development of Ab32-27M reactivity. The identity of the antigenic structures developed after addition of fetal bovine serum or NeuGc-GM3 was determined by analysis of the gangliosides from both samples. The major component detected in melanoma cell lines was shown to be N-acetylneuraminic acid-NeuGc-GD3. Another, slower moving component, present in some melanomas and in astrocytomas may be N-acetylneuraminic acid-NeuGc-GD2. The cell type specificity for these processes can be most readily explained by postulating that all cells can take up exogenous gangliosides but only melanoma and astrocytoma cells have sufficiently high levels of GM3 alpha 2----8-sialyltransferase for the conversion of added NeuGc-GM3 to disialogangliosides to be effective. These results demonstrate a novel pathway for exogenous glycolipid processing that can lead to novel Ag expression but may also play a role in normal glycolipid metabolism and function.