Intracarotid cisplatin chemotherapy for recurrent gliomas

Forty patients with recurrent gliomas were treated with monthly intra-arterial infusions of cisplatin. Of the 35 evaluable patients, 12 (34%) responded with computerized tomography (CT) evidence of a decrease in tumor size; in 14 (40%) the tumor stabilized on CT scans, and in nine (26%) the disease progressed. The median survival period was 35.0 weeks for the responders and 27.5 weeks for all 35 patients. The primary toxicities were renal (reversible alterations in creatinine clearance), otological (severe hearing loss in one patient), and likely neurotoxicity in one patient who had received bilateral infusions following contralateral tumor progression. The authors are now using this form of regional chemotherapy sequentially before and following radiotherapy in newly diagnosed cases.

Systemic gamma-interferon therapy for recurrent gliomas

Recombinant gamma-interferon (2 mg/sq m) was administered intravenously twice weekly in 8-week courses to 14 patients with recurrent gliomas. Computerized tomography (CT) evidence of response was seen in only one patient, and stabilization for 12 to 86 weeks was recorded in three. This was a disappointing result, particularly in a series of patients with relatively small initial tumor volumes (less than 50 cu mm on enhanced CT) and Karnofsky functional ratings of 70 or higher. In addition, several instances of toxicity potentially attributable to gamma-interferon were observed.

Effect of methylprednisolone on radiotherapy of F344 rats with avian sarcoma virus induced gliomas

We have examined the impact of methylprednisolone acetate (MPA) on survival of F344 rats that were bearing avian sarcoma virus (ASV)-induced gliomas and that were treated optimally with radiotherapy. Toxicity of MPA (dose range of 0.2-5.0 mg/kg X 7 over 3 weeks) was first established in non-tumor bearing rats as assessed by their relative failure to gain weight. Doses of 2.0 or 5.0 mg/kg X 7 caused animals to be 21.8 or 43.9%, respectively, underweight compared with vehicle controls. In rats bearing ASV-induced gliomas, treatment with 3,000 cGY (nine fractions over a 3-week period) alone or with 0.2 or 1.0 mg MPA/kg (X 6 during the 3-week radiotherapy course) produced a significantly prolonged survival compared with that of untreated, tumor bearing rats. However, MPA did not enhance survival when given concurrently with radiotherapy; indeed, at the higher of these two doses, median survival of tumor-bearers was slightly less than with radiotherapy alone. This trend towards interference with the beneficial effects of radiotherapy was more pronounced with the highest dose of MPA studied, 5.0 mg/kg body weight X 6. These animals had a median survival time that was significantly less than that of tumor-bearers receiving radiotherapy alone, but not significantly different from untreated rats with gliomas. The possible significance of these observations is discussed.

Monoclonal antibody specific for the transverse tubular membrane of skeletal muscle activates the dihydropyridine-sensitive Ca2+ channel

In skeletal muscle, dihydropyridine receptors and dihydropyridine-sensitive Ca2+ channels are preferentially localized in the transverse tubular membranes. Starting with an antigenic membrane fraction enriched in rabbit muscle transverse tubules (T-tubules), several monoclonal antibodies were produced by a fusion of spleen cells from an immunized BALB/c mouse with P3 X 63Ag.8.6.5.3 mouse myeloma cells. Antibodies were screened according to a scheme designed to select IgG immunoglobins that recognized a determinant specifically associated with the T-tubule membrane. Antibodies that fulfilled the screening criteria were used in in vitro planar bilayer recording of the activity of the dihydropyridine-sensitive Ca2+ channel present in T-tubules. Cells producing one antibody (Ab 21) survived cloning dilution and stably produced a monoclonal antibody (mAb21-4) that increased the rate of single channel opening when interacting with the internal side of the channel protein. mAb21-4 immobilized by covalent crosslinking on beads (Affi-Gel 10) consistently immunoprecipitated polypeptide bands with the following electrophoretic mobility: Mr values of greater than or equal to 175,000; 90,000; 55,000; and 34,000.

Treatment of autochthonous rat brain tumors with steroid plus heparin: a brief report

Treatment of rats bearing intracranial gliomas induced by the avian sarcoma virus with heparin plus steroid has failed to effectively extend survival time.

Differential retention of rhodamine 123 by avian sarcoma virus-induced glioma and normal brain tissue of the rat in vivo

The time course of uptake, retention and clearance of the cationic lipophilic dye, rhodamine 123 (Rh123), within the central nervous system was qualitatively evaluated in rats. Weanling rats were injected intracerebrally with avian sarcoma virus, which induced malignant gliomas in situ before injection of Rh123. Comparison was made of the amount of fluorescence of Rh123 within the normal cerebral cortex, myelinated tracts of the brain, meninges, choroid plexus, and neoplastic foci at 1, 4, 8, 12 and 24 hours after intravenous injection. Fluorescence microscopy was utilized to identify tissues containing the dye. Normal neuropil did not contain Rh123 at any of the time periods studied. Gliomas retained the dye at 1, 4, 8 and 12 hours, with increasing uniformity of distribution and decreasing intensity of fluorescence over this time period. Fluorescence was not detected at 24 hours within the neoplastic tissues, but was evident at all time periods studied within the choroid plexus. The specific retention of Rh123 by malignant glioma and by the choroid plexus in vivo suggests that Rh123 may be useful for photochemotherapeutic treatment of brain neoplasms and disorders of the choroid plexus.

Derivation of monoclonal antibodies to human somatomedin C/insulin-like growth factor I

Somatomedin C, also called insulin-like growth factor I (Sm-C/IGF-I), is a highly conserved polypeptide required for the proliferation of many cell types. Since several attempts in our laboratory to recover monoclonal antibody-secreting hybrids to this peptide by the direct fusion of hyperimmunized splenocytes with myeloma cells had been unsuccessful, we modified our approach by coculturing hyperimmunized BALB/c splenocytes and a small amount of the antigen for 5 days prior to fusion with the P3X63Ag.8.653 myeloma cell line. Of 88 microcultures at risk, specific antibody was detected in 24. Two clones were expanded in ascites fluid and characterized as to isotype, affinity, and specificity. Both were IgG1,kappa and bound human Sm-C/IGF-I with affinity constants of 1.09 and 1.01 X 10(10) liter/mol, respectively. Both clones were quite specific for Sm-C/IGF-I with inconsequential binding to insulin-like growth factor II, multiplication-stimulating activity, any of the chymotryptic fragments of Sm-C/IGF-I, insulin preparations, hGH, hTSH, mEGF, or mouse albumin. In vitro boosting after primary in vivo immunization appears to provide monoclones of an IgG isotype in contrast to primary in vitro immunization, which reportedly favors an IgM isotype. The antibodies produced in this study have proved to be extraordinarily useful in defining the physiologic role of Sm-I/IGF-I with immunoneutralization techniques and in the purification of human Sm-C/IGF-I by affinity chromatography.

Laser photochemotherapy of rhodamine-123 sensitized human glioma cells in vitro

The photochemotherapeutic effect of the mitochondria-specific dye rhodamine-123 (Rh-123) on human glioma cells in culture was studied. Cultured U-251MG glioma cells were incubated for 30 minutes in 10 micrograms/ml of Rh-123 and then exposed to blue-green light between 488 and 514.5 nm using a continuous-wave argon laser. Cells that were treated with Rh-123 and the argon laser at power densities less than 200 mW/sq cm demonstrated increasing tumor-cell killing with increasing time of exposure to laser light. Tumor-cell killing achieved with power densities of light less than 200 mW/sq cm was shown to be due solely to a photochemical effect and not to a direct (thermal) effect of the laser. The photochemical effect was dependent upon the intracellular concentration of Rh-123 and the length of light exposure, and not the intensity of light. The selective retention of Rh-123 by glioma cells and its exclusion from normal cells in conjunction with its photoactivated cytotoxicity suggest that Rh-123 may be a useful photosensitizing drug for the treatment of malignant gliomas in situ.

Monoclonal antibody specific for the T-tubule of skeletal muscle

Monoclonal antibodies were raised against a triad-enriched (sarcoplasmic reticulum-T-tubule complex) microsomal membrane fraction of rabbit skeletal muscle. The avidin-biotin complex (ABC) immunoperoxidase staining method was used to screen hybrid colonies. Positive antibodies exhibited a granular doublet pattern at the A-I junction, consistent with the location of triads in rabbit muscle. One monoclonal antibody, M171, was further characterized by ultrastructural and immunoadsorption techniques. Postembedding electron immunocytochemistry was performed on tissue sections embedded in Lowicryl K4M. Goat anti-mouse immunoglobulin absorbed to 10 nm colloidal gold particles was used as an ultrastructural label. In these studies, M171 recognized an epitope at the triads and at periodic openings along the plasmalemma. Immunoadsorption on protein transfers of isolated sarcoplasmic reticulum, surface membrane (plasmalemma and T-tubule), and triad-enriched fractions showed that M171 reacts with a surface membrane component. Taken together, these studies suggest that M171 recognizes an epitope associated with the T-tubule at the triad and at the "mouth" of the T-system at the plasmalemma.

Juxtadrenal schwannoma: verification of the diagnosis by immunohistochemical and ultrastructural studies

Solitary schwannomas arising in the juxtadrenal region are exceedingly rare. A middle-aged woman with a confusing clinical course was found to have a solid periadrenal mass, which was surgically excised. The gross and light microscopic appearance of the tumor was suggestive but not diagnostic of this entity. However, electron microscopic evaluation of the neoplasm revealed prominent basal lamina and interdigitating cellular processes characteristic of a schwannoma. The diagnosis of schwannoma was further supported by the demonstration of S-100 protein, type IV (basement membrane) collagen, and laminin immunoreactivity by immunohistochemical techniques. The use of these special studies to arrive at the diagnosis in this case and in the larger context in the diagnosis of rare adrenal and periadrenal tumors of uncertain origin is fully discussed.

Characterization of distinct tyrosine-specific protein kinases in B and T lymphocytes

Lymphocyte membrane fractions from both normal and neoplastic sources exhibit tyrosine-specific protein kinase activity. The molecular weights of the endogenous substrates phosphorylated on tyrosine residues differ in B and T cells. To further characterize membrane tyrosine phosphorylation in the two major classes of lymphocytes, the tryptic phosphopeptides of their endogenous substrates were compared and the sensitivity of the kinases to inhibition by N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) was determined. The two major B cell substrates (61,000 and 55,000 daltons, p61 and p55) were gel purified after phosphorylation and exhaustively digested with trypsin. Separation by reverse phase high pressure liquid chromatography demonstrated that these two substrates had two identical phosphotyrosine containing tryptic phosphopeptides. p61 had an additional phosphotyrosine site. Parallel analysis of the two T cell substrates (64,000 and 58,000 daltons, p64 and p58) showed that they also contained two phosphotyrosine sites that were identical. However, the tryptic phosphopeptides from the B and T cell substrate pairs were clearly distinct suggesting that they arise from different gene products. When B and T cell membrane fractions were preincubated with TLCK (21 degrees C, 30 min) a dose-dependent decrease in p64 and p58 phosphorylation resulted. p61 and p55 phosphorylation was not affected at concentrations up to 10 mM TLCK. Tyrosine-specific kinase activity was also assessed by measuring phosphorylation of a tyrosine containing synthetic peptide. The kinase activity of T cell plasma membrane fractions was inhibited by TLCK; the B cell activity was unaffected. The results suggest that membrane fractions from normal and some neoplastic B and T cells have at least two different tyrosine-specific kinases.

Cellular immunolocalization of S100 protein within fixed tissue sections by monoclonal antibodies

Monoclonal antibodies (MoAb) that cross-react with the shared epitopes of S100 protein have been prepared from mouse hybridoma cell lines and partially characterized. Nine of these MoAb were applied to sections of formaldehyde-fixed paraffin-embedded human tissues that were stained by immunohistochemical techniques. Three of these MoAb give uniformly and reproducibly positive staining in appropriate cell types when stained by avidin-biotin methods. Three of the MoAb were judged to be negative, although some MoAb gave inappropriate staining patterns. The three remaining MoAb showed either great heterogeneity in their staining patterns or intensities, or gave a lesser degree of reproducibility in a given tissue or neoplasm. One of the MoAb designated 15E2E2 that belonged to the first group of reproducibly staining antibodies was used to stain a larger number of normal human tissues and neoplasms. The staining that was observed appeared to recapitulate that which was previously described for conventional S100 protein antibodies. Monoclonal antibodies may, therefore, have a role in selected cases where standard microscopy is equivocal for a specific tissue diagnosis, or where independent verification of the diagnosis would be beneficial.

Interferon-alpha and -gamma promote myeloid differentiation of HL-60, a human acute promyelocytic leukemia cell line

Two different preparations of ultrapurified interferon-alpha (IFN-alpha) (lymphoblastoid and peripheral blood leukocyte) and one of IFN-gamma were tested for their ability to induce terminal differentiation and alter cell growth in three human leukemia cell lines of different hematological origin (HL-60, K562, U937). Cell lines were cultured for 9 days in the presence of 500 units/ml of either IFN-alpha or of IFN-gamma. Cell counts and stained differentials were made on days 3, 6, and 9 to assess the effects of IFN. A marked heterogeneity of response was found, not only among cell lines, but among the IFNs tested. The most striking morphological changes were noted in the HL-60 acute promyelocytic leukemia cell line. All three IFNs tested induced significant myeloid maturation, with increased numbers of terminally differentiated myelocytes and metamyelocytes seen as early as day 3 of culture. The feasibility of using IFNs as an adjunctive or alternative therapy for the treatment of some types of leukemias is discussed.

Membranes from T and B lymphocytes have different patterns of tyrosine phosphorylation

Membrane fractions isolated from mouse and rat spleen expressed substantial tyrosine-specific protein kinase activity. Phosphotyrosine (P-Tyr) accumulation in endogenous membrane substrates was stimulated by vanadate or nonionic detergents. When in vitro phosphorylation was carried out at 0 degree C in the presence of 1 mM Mn2+ and Triton X-100, P-Tyr constituted up to 40-50% of the total phospho amino acid. Polyacrylamide gel electrophoresis showed that membranes from mixed lymphocyte populations have four major P-Tyr-containing proteins. Whereas nonionic detergents were potent stimuli for P-Tyr accumulation in all four substrates, tyrosine phosphorylation of two of these (p61 and p55) was markedly dependent on vanadate. These two substrates were present in membranes from surface Ig-bearing splenic lymphocytes purified by affinity chromatography and Raji, a human B-lymphoblastoid cell line. P-Tyr accumulation in the two other substrates observed in splenocyte membranes (p64 and p58) was much less dependent on vanadate. p64 and p58 were phosphorylated in membranes from mouse thymocytes and human and mouse T-lymphoma cell lines, while p61 and p55 were not. Thus it appears that in both murine and human lymphocytes, p64 and p58 served as T-cell-specific substrates, while p61 and p55 were specifically associated with B lymphocytes. Moreover, these distinct P-Tyr substrate patterns were conserved in some neoplastic cell lines derived from B and T cells.

Macrophage-derived growth factor for fibroblasts and Interleukin-1 are distinct entities

P388D1, a mouse macrophagelike cell line, was adapted to grow continuously in an unsupplemented, serum-free culture medium and continued to elaborate substances that were mitogenic for quiescent mouse fibroblasts (BALB/c 3T3 cells) and for thymocytes suboptimally stimulated with lectins. We have previously described [37] the fibroblast mitogenic activity as a macrophage-derived competence factor (MDCF). Serum-free, macrophage-conditioned culture medium was concentrated 1,000-fold by a combination of ultrafiltration (hollow fiber) and lyophilization. Concentrates of medium were subjected to gel filtration (Sephadex G-75 or G-150), and the fractions were assayed for mitogenic activity (MDCF) on density-arrested BALB/c 3T3 cells and for Interleukin-1 (IL-1) activity in suboptimally stimulated (Con A) mouse thymocytes. The apparent molecular weight (MW) of MDCF activity was estimated at 56,000 daltons, whereas the peak of IL-1 chromatographed at an apparent MW of 14-16K daltons. There was no detectable IL-1 activity in the MDCF fractions and no detectable MDCF in the IL-1 fractions. These data indicate that P388D1 cells produce both MDCF and IL-1 activities under continuous serum-free conditions and that the two activities are not identical. Stimulation of responsive mononuclear phagocytes with lipopolysaccharide and/or lymphokine-rich supernates resulted in a differential modulation of MDCF and IL-1 activities. Finally, antibody-purified IL-1 had no significant ability to stimulate DNA synthesis in quiescent fibroblasts at concentrations that were mitogenic for thymocytes. However, IL-1 did augment the mitogenic activity of suboptimal amounts of platelet-derived growth factor (PDGF), another competence factor. Further studies revealed that neither the generation nor the activity of MDCF was modulated by the presence of various inhibitors of proteolytic enzymes.

Tumoricidal activity of an acute promyelocytic leukemia cell line (HL-60) is augmented by human interferon alpha

Normal human peripheral blood polymorphonuclear leukocytes (PMNs) and cells from a human acute promyelocytic leukemia line (HL-60) were tested for cytotoxic potential against two human glioma and one normal fibroblast line. Both the PMNs and HL-60 exhibited significant cytotoxicity against the tumor targets while sparing the normal fibroblasts. However, the two glioma cell lines were not equally susceptible to the effector cells. Addition of low levels of purified human lymphoblastoid interferon alpha (IFN) during the assay period significantly enhanced the tumoricidal effect against one of the glioma targets. HL-60 cells, partially differentiated to myelocytes and metamyelocytes by incubation with dimethylsulfoxide (DMSO), expressed reduced levels of cytotoxicity; IFN added during the assay was able to restore the cytotoxic activity against both glioma cell lines. Undifferentiated HL-60 cells were also able to lyse K562 targets in a six hour 51Cr release assay; this activity was also significantly enhanced by IFN. Separate incubation of both effectors and targets proved that the enhancement of cytotoxic activity demonstrated was due to an effect on the HL-60 effector cells. In contrast, the lysis of HSB-2, another NK sensitive target cell, was not enhanced by the addition of IFN to a mixture of HSB-2 and HL-60 cells. Pretreatment of effector and target cells separately with IFN demonstrated a dual effect: IFN both protected HSB-2 targets from lysis by the HL-60 effectors and induced significantly greater cytotoxicity by HL-60 cells.

Immunobiology of primary intracranial tumors. Part 8: Serological responses to active immunization of patients with anaplastic gliomas

Serial serological studies were carried out on 19 of 20 patients with malignant gliomas who were actively immunized with one of two human glioma tissue culture cell lines (D-54MG or U-251MG). Most patients mounted a significant serum reaction to histocompatibility antigens (HLA's), as well as an antibody response to fetal bovine serum (FBS) which was added to the glioma-cell inoculum. These two sources of antibody accounted for greater than 90% of the antibody induced by these inoculations. Two patients continued to have significant amounts of binding antibody to the original immunizing cell line following exhaustive absorptions of FBS and these two had all remaining significant antibody removed by further absorption of the serum against the 2-T osteogenic sarcoma tissue culture cell line known to possess antigens cross-reactive with human gliomas. One single patient continued to show significant antibody binding to the original glioma cell line following absorption against FBS, human platelets, and the 2-T cell line, and therefore seems to have produced glioma-distinctive antibodies in response to immunization. The antibody preparation from this patient was also cytotoxic against the original glioma cell line, as well as another recently cultured human glioblastoma cell line. The significance of these serological studies is discussed as it relates to immunological responses patients with gliomas may make to active immunization.

Mitogenic activity elaborated by macrophage-like cell lines acts as competence factor(s) for BALB/c 3T3 cells

The culture medium from several murine macrophage-like cell lines contained a mitogenic activity that functioned synergistically with platelet-poor plasma to induce DNA synthesis in quiescent density-inhibited BALB/c 3T3 fibroblasts. This mitogenic activity was generated by P388D1 (and other established lines of) macrophage-like cells that were cultured either in medium alone or in medium supplemented with platelet-poor plasma. The amount of mitogenic activity produced was directly related to the length of time the macrophage-like cells were maintained in the medium. Serum-free medium conditioned by macrophage-cells did not stimulate DNA synthesis in density-inhibited 3T3 cells in the absence of plasma; however, a transient (4-hr) exposure to serum-free macrophage-conditioned medium allowed quiescent cells to respond to plasma-derived progression factors. The addition of plasma to 3T3 cells that had been treated with the macrophage-conditioned medium brought about DNA synthesis after a 12-hr lag. The mitogenic activity that was in macrophage-conditioned medium bound to DEAE-Sephadex and eluted in a single peak using a linear NaCl gradient. This macrophage-derived competence factor was not mitogenic for lymphocytes and was clearly separated by DEAE-Sephadex chromatography from the major peak of the previously described mitogenic monokine, Interleukin-1 (lymphocyte activating factor).

Resurgence of killing and in vivo protection mediated by lymphocytes cultured from lymph nodes draining Moloney sarcomas

We have previously documented the development and subsequent disappearance of cytolytic activity mediated by lymphocytes from lymph nodes draining Moloney sarcomas destined either to regress or grow progressively. We now report that these tumour-draining lymphnode cells (LNC) that were no longer cytotoxic, spontaneously regenerated peak levels of killing after culture in vitro for 4 days in the absence of exogenous tumour antigen. Cytolytic activity, which was antigenically specific, was mediated by T lymphocytes. Resurgence of cytolytic activity in vitro was accompanied by proliferative changes (DNA synthesis, blast transformation, cell division) which peaked on the 3rd day of culture. Although normal, nonimmune LNC underwent quantitatively similar proliferative changes in culture, the killing that developed was weak and antigenically nonspecific. Transfer of cultured, tumour-draining LNC to immunologically compromised, syngeneic mice conferred complete protection from Moloney sarcoma progression. Adoptive transfer could be delayed for 6 days after tumour induction without loss of protection. These results suggest that there exists in Moloney sarcoma-bearing mice a mechanism that limits the differentiation of pre-killer cells into cytolytically active T lymphocytes, and that such inhibition is eliminated when LNC are explanted into culture.

B-tropic oncornavirus production by BALB/c methylcholanthrene-induced sarcoma cells

Six oncogenic cell lines were established from primary sarcomas that had been induced in thymectomized, aged, BALB/cSt mice by the injection of 3-methylcholanthrene. Of these lines, three produced B-tropic murine leukemia virus (MuLV), i.e. MuLV that would patently infect fibroblasts of BALB/c origin but not those from NIH Swiss mice. One of these lines, M-138, produced large quantities of virus, permitting the isolation of milligram quantities of B-tropic MuLV. Neonatal BALB/c mice injected with the M-138 MuLV developed high plasma levels of the species-specific virion antigen p30, but during 9 months of observation failed to manifest clinical signs of leukemia. Plasma p30 levels of NIH Swiss mice (non-permissive host) that were inoculated also as neonates with the same virus preparation, remained undetectable by radioimmunoassay. Xenotropic MuLV, i.e. that which infects cells of species other than the species of origin, was released by one of the three remaining cell lines. Two of the six original lines have remained free of detectable oncornavirus production. Our results suggest that cell lines that are stable sources of large quantities of B-tropic MuLV may be easily obtainable by the described manipulations. Equally important, however, is the fact that these data re-emphasize the danger that is inherent in assuming that a cell line is virus-free simply because it was isolated from a chemical carcinogen-induced neoplasm

Development and persistence of cytolytic T lymphocytes in regressing or progressing Moloney sarcomas

Intratumoral T lymphocytes were recovered sequentially after induction of regressing or progressing Moloney sarcomas in BALB/c mice and were assayed quantitatively for their ability to kill specifically the tumor (MSC) cells used for induction. The cytolytic activities of the two lymphocyte populations described two distinct biphasic kinetic profiles that were similar in amplitude and duration but separated from each other by 4-6 days. In progressing neoplasm, there was a rapidly occuring accumulation of T lymphocytes highly cytolytic for MSC cells. This response, however, was not sustained and disappeared in association with the onset of unchecked tumor growth. In contrast, T lymphocyte cytolytic activity developed more slowly in regressing sarcomas and attained peak levels coincident with the beginning of tumor regression. Similar changes in cytolytic activity characterized T lymphocytes in lymph nodes draining tumors. When cultured in vitro for 4 days, non-cytotoxic T lymphocytes from regional lymph nodes draining progressing sarcomas regained very high levels of cytolytic activity. Such restitution was diminished, however, if MSC cell lysates, macrophages or macrophages fed MSC cell lysates were present during the culture period. These experiments provided presumptive evidence that T lymphocyte-mediated cytolytic activity was lost in progressively growing Moloney sarcomas as a consequence of suppression in vivo of the genesis and/or functional expression of cytolytic T lymphocytes, perhaps by macrophages and/or soluble tumor antigen.

Inflammatory cells in solid murine neoplasms. IV. Cytolytic T lymphocytes isolated from regressing or progressing Moloney sarcomas

Highly purified suspensions of intratumoral T lymphocytes, recovered 11 and 13 days after induction of regressing or progressing Moloney sarcomas, were compared in their ability to lyse specifically the MSC cells used for tumor induction. Cytolytic activity, expressed in terms of lytic units/10(6) T cells, was similar for intratumoral T cell suspensions obtained 11 days after induction of either regressing (3.1 +/- 1.3 LU/10(6) T cells) or progressing (4.3 +/- 1.8) neoplasms. By 13 days post-induction, regressing tumors contained T lymphocytes with an increased cytolytic activity (11.1 +/- 4.5) whereas those from progressing tumors were strikingly less able to kill MSC cells (less than or equal to 0.2). This dramatic loss in cytotoxicity could not be attributed to errors associated with the enzymatic disaggregation method, inhibition by copurified endogenous tumor cells, or immunosuppression induced by viral infection. The changes in functional activity of intratumoral T lymphocytes from the two types of sarcoma appeared to be correlated with the stage of neoplasia. In this model system, cytolytic activity of T lymphocytes increased during spontaneous tumor regression whereas losses in cytotoxicity occurred coincident with the onset of inexorable progression.

Inflammatory Cells in Solid Murine Neoplasms

Highly purified suspensions of intratumoral T lymphocytes, recovered 11 and 13 days after induction of regressing or progressing Moloney sarcomas, were compared in their ability to lyse specifically the MSC cells used for tumor induction. Cytolytic activity, expressed in terms of lytic units/106 T cells, was similar for intratumoral T cell suspensions obtained 11 days after induction of either regressing (3.1 ± 1.3 LU/106 T cells) or progressing (4.3 ± 1.8) neoplasms. By 13 days post-induction, regressing tumors contained T lymphocytes with an increased cytolytic activity (11.1 ± 4.5) whereas those from progressing tumors were strikingly less able to kill MSC cells (≤ 0.2). This dramatic loss in cytotoxicity could not be attributed to errors associated with the enzymatic disaggregation method, inhibition by copurified endogenous tumor cells, or immunosuppression induced by viral infection. The changes in functional activity of intratumoral T lymphocytes from the two types of sarcoma appeared to be correlated with the stage of neoplasia. In this model system, cytolytic activity of T lymphocytes increased during spontaneous tumor regression whereas losses in cytotoxicity occurred coincident with the onset of inexorable progression.

Isolation of T-lymphocytes from disaggregated tumors, with high purity and good percentage recovery

A combination of two cell separation methods was utilized for the isolation of thymus-derived lymphocytes (TL) from enzymatically disaggregated tumors. Passage through Sephadex G-10-glass bead columns to remove adherent cell types followed by exposure to IgG-coated sheep red blood cell monolayers for removal of Fc receptor-bearing inflammatory cells provided functional TL suspensions of high purity with good percentage recovery.

Inflammatory cells in solid murine neoplasms. III. Cytotoxicity mediated in vitro by macrophages recovered from disaggregated regressing Moloney sarcomas

Macrophages (Mphi) were recovered from disaggregated, spontaneously regressing Moloney sarcomas for in vitro testing of their cytotoxic capabilities. At a 3:1 ratio, Mphi in monolayers efficiently killed (51Cr release) a variety of tumor target cells without regard to antigenic specificity. Within 24 hr most of their cytolytic potential was lost. Killing could be restored, however, if Mphi were replated at higher cell densities. A soluble, heat-stable, dialyzable inhibitor of thymidine incorporation, which did not interfere with cellular proliferation, also was produced by Mphi recovered from Moloney sarcomas. The finding of such a competitive inhibitor, probably cold thymidine, in supernatants further opened to question the validity of radioisotope incorporation into DNA as a measure of Mphi-mediated cytostasis. The data presented suggest that Mphi may participate in the regression process by directly killing tumor cells, thus complementing the antigen-specific cytolytic capabilities of the T lymphocytes that are also found in large numbers within regressing Moloney sarcomas.

Inflammatory Cells in Solid Murine Neoplasms

Macrophages (Mø) were recovered from disaggregated, spontaneously regressing Moloney sarcomas for in vitro testing of their cytotoxic capabilities. At a 3:1 ratio, Mø in monolayers efficiently killed (51Cr release) a variety of tumor target cells without regard to antigenic specificity. Within 24 hr most of their cytolytic potential was lost. Killing could be restored, however, if Mø were replated at higher cell densities. A soluble, heat-stable, dialyzable inhibitor of thymidine incorporation, which did not interfere with cellular proliferation, also was produced by Mø recovered from Moloney sarcomas. The finding of such a competitive inhibitor, probably cold thymidine, in supernatants further opened to question the validity of radioisotope incorporation into DNA as a measure of Mø-mediated cytostasis. The data presented suggest that Mø may participate in the regression process by directly killing tumor cells, thus complementing the antigen-specific cytolytic capabilities of the T lymphocytes that are also found in large numbers within regressing Moloney sarcomas.

Inflammatory cells in solid murine neoplasms. II. Cell types found throughout the course of Moloney sarcoma regression or progression

Regressing and progressing Moloney sarcomas, induced in BALB/c mice by the injection of cultured sarcoma cells (MSC)1, were sampled for histologic analysis and then disaggregated using mixtures of trypsin, collagenase and DNAse or collagenase and DNAse alone. The types of inflammatory cells (IC) found in resultant cell suspensions were determined 6, 11, 14 and 18 days post inoculation. Inflammatory infiltrates were composed almost exclusively of three cell types; neutrophils, T lymphocytes and macrophages. The extent to which each was found in tumors was related to the time post inoculation. Neutrophils were part of an early acute inflammatory response seen in both developing regressing and progressing sarcomas. The onset of regression was associated histologically with the appearance within tumors of a mononuclear inflammatory infiltrate. T lymphocytes and macrophages were the principal constituents. A higher percentage of T lymphocytes was recovered at all sampling times from regressing, compared to progressing, sarcomas. During development of the mononuclear inflammatory infiltrate there were relatively more large T cells in regressing, than in progressing tumors, and the percentage of macrophages was higher. Thereafter, the proportion of macrophages in the recovered cell population was approximately the same for both types of tumor. Such equality was more apparent than real, however, since IC were restricted to the peripheries of progressing sarcomas after the acute inflammatory phase, but continued to be found throughout regressing neoplasms. The effective ratio of macrophages and T lymphocytes to tumor cells therefore was much lower in progressing sarcomas than was suggested by percentage figures. The data presented support the concept that T lymphocytes are instrumental in causing the regression of Moloney sarcomas, possibly through interactions with macrophages.

Studies on the role of macrophages in regulation of growth and metastasis of murine chemically induced fibrosarcomas

Murine solid tumors were shown to contain 9-54% medium to large non-malignant cells bearing receptors for immunoglobulin Fc. These cells rapidly adhered to plastic surfaces, were trypsin-resistant, were capable of phagocytosis of latex particles and were sensitive to the lytic effects of anti-macrophage serum and complement. Purified Fc-receptor-positive cells failed to produce tumors, which strongly suggested that they were macrophages. When tumor-cell suspensions, depleted of macrophages by adherence to plastic surfaces, were injected subcutaneously into normal syngeneic mice, the tumors displayed an increased potential for metastasis. By contrast, control animals which received tumor-cell suspensions containing their normal complement of macrophages invariably developed progressive localized tumors. The survival times of mice infected with macrophage-depleted tumor-cell suspensions were significantly shorter (p less than 0.05) than those for animals inoculated with intact tumor-cell suspensions. These studies confirm the existence of a substantial number of macrophages within progressing syngeneic murine solid tumors and strongly suggest a regulatory role for the macrophages in the growth and metastasis of the tumor.

Receptor Sites for Antigen-Antibody Complexes on Cells Derived from Solid Tumors: Detection by Means of Antibody Sensitized Sheep Erythrocytes Labeled with Technetium-99m

Surface receptor sites for the Fc portion of antigen-antibody complexes were demonstrated on cells derived from three methylcholanthrene-induced fibrosarcomas, one of strain C3H and two of strain BALB/c origin, two spontaneously occurring malignant melanomas (B16 in strain C57BL/6 and Harding-Passey in strain BALB/c mice), a Moloney sarcoma virus-induced tumor of strain BALB/c origin and the Walker 256 carcinosarcoma of Holtzman rats. Primary cell cultures derived from these tumors adsorbed technetium-99m labeled, antibody-sensitized sheep erythrocytes (99mTc EA) as determined either by visual scoring of adherence or radioisotopic quantitation. Depending upon the tumor tested, from 20% to greater than 95% of the target cells absorbed 99mTc EA. All cells lost their reactivity after 1 or 2 passages in vitro, but this was regained after a single passage in vivo. Indicator erythrocytes coated with F(ab′)2 fragments of the sensitizing sheep erythrocytes (SRBC) antiserum did not adhere thereby demonstrating that the hemadsorption required an intact Fc portion of the antibody molecule. Adherence of 99mTc EA was blocked by soluble immune complexes prepared with ovalbumin and rabbit antibody directed against it and Escherichia coli 055:B5 lipopolysaccharide and mouse antibody directed against it. Normal rabbit or mouse serum, immune serum, or antigen alone did not block adherence of 99mTc EA thereby demonstrating that the receptors had greater affinity for immune complexes than for either antigen or antibody alone. The existence of membrane receptors on tumorderived cells which react with the Fc portion of antigen-antibody complexes may provide an explanation for the mechanism by which immune complexes are capable of blocking cell-mediated tumor cell destruction irrespective of whether the receptors are on the tumor cells themselves or on admixed lymphocytes and macrophages.

Receptor sites for antigen-antibody complexes on cells derived from solid tumors: detection by means of antibody sensitized sheep erythrocytes labeled with technetium-99m

Surface receptor sites for the Fc portion of antigen-antibody complexes were demonstrated on cells derived from three methylcholanthrene-induced fibrosarcomas, one of strain C3H and two of strain BALB/c origin, two spontaneously occurring malignant melanomas (B16 in strain C57BL/6 and Harding-Passey in strain BALB/c mice), a Moloney sarcoma virus-induced tumor of strain BALB/c origin and the Walker 256 carcinosarcoma of Holtzman rats. Primary cell cultures derived from these tumors adsorbed technetium-99m labeled, antibody-sensitized sheep erythrocytes (99mTc EA) as determined either by visual scoring of adherence or radioisotopic quantitation. Depending upon the tumor tested, from 20% to greater than 95% of the target cells absorbed 99mTc EA. All cells lost their reactivity after 1 or 2 passages in vitro, but this was regained after a single passage in vivo. Indicator erythrocytes coated with F(ab')2 fragments of the sensitizing sheep erythrocytes (SRBC) antiserum did not adhere thereby demonstrating that the hemadsorption required an intact Fc portion of the antibody molecule. Adherence of 99mTc EA was blocked by soluble immune complexes prepared with ovalbumin and rabbit antibody directed against it and Escherichia coli 055:B5 lipopolysaccharide and mouse antibody directed against it. Normal rabbit or mouse serum, immune serum, or antigen alone did not block adherence of 99mTc EA thereby demonstrating that the receptors had greater affinity for immune complexes than for either antigen or antibody alone. The existence of membrane receptors on tumor-derived cells which react with the Fc portion of antigen-antibody complexes may provide an explanation for the mechanism by which immune complexes are capable of blocking cell-mediated tumor cell destruction irrespective of whether the receptors are on the tumor cells themselves or on admixed lymphocytes and macrophages.