Biomedical subjects

M D Prager

Publications and source records attributed to M D Prager.

At least 37 records · Page 2Linked to original sources

PubMed1978

Effects of levamisole on normal and malignant murine lymphocytes.

Levamisole enhanced transformation of murine lymphocytes stimulated either by mitogens or allogeneic lymphocytes. In a similar dose-dependent pattern it stimulated in vitro growth of L1210, P1798, and 6C3HED but not YAC lymphoma cells. Stimulation of growth of lymphoma cells was greater by peritoneal cells harvested from normal mice 4 days after levamisole injection than by peritoneal cells from untreated mice. This effect correlated with the shortened survival time of BALB/c mice treated with levamisole prior to P1798 implantation compared to that of a control group not pretreated. Administration of levamisole with iodoacetamide-modified tumor cells in immunoprophylaxis studies had no effect on the rejection of a tumor implant or on development of tumor-specific antibody. Levamisole was added to regimens involving asparaginase therapy of 6C3HED-bearing C3H mice and chemoimmunotherapy of BALB/c mice bearing P1798 with methotrexate and iodoacetamide-modified P1798 cells. In neither case were there increased numbers of survivors, and mean survival time was generally decreased for the levamisole-treated groups. The stimulated tumor growth may have been mediated by a direct effect of levamisole on the lymphoma cells, through an effect on other cell types, or by both effects; these effects apparently outweighed potentially beneficial effects of levamisole on the immune system.

Animals↗

PubMed1978

Effect of sera of patients with genitourinary tract cancers on transformation of lymphocytes stimulated with anti-thymocyte globulin.

Serum from patients with genitourinary cancer was tested for ability to support transformation of autologous or normal lymphocytes stimulated with ATG. Selected for specificity for T-lymphocytes, ATG at times gave a more sensitive indication of a serum defect than did PHA. Although poor transformability in the presence of patient serum suggests an inhibitor, this test cannot rule out the possibility of a limitation of an essential nutrient usually supplied by serum. Presence of inhibitor(s) was more strongly indicated by contrasting transformation of normal lymphocytes with patient serum against a panel of normal sera. The presence of circulating inhibitor(s) was confirmed by demonstrating depression of transformation of normal lymphocytes in complete medium by chromatographic fractions from patient serum that did not support transformation. In several instances, patient serum was more inhibitory of autologous than normal lymphocytes, which suggested an additional way of examining host immune competence.

Antilymphocyte Serum↗

PubMed1978

Enhanced response to chemoimmunotherapy and immunoprophylaxis with the use of tumor-associated antigens with a lipophilic agent.

Treating iodoacetamide (IAD)-modified lymphoma cells with the lipophilic agent dimethyldioctadecylammonium bromide (DDA) increased their immunogenicity as evidenced by the increased capacity of syngeneic, vaccinated hosts to reject subsequent implants of the same lymphoma. Under conditions of suboptimal immunization to facilitate comparison, there were 61% survivors among mice challenged with tumor implants after immunization with modified cells and DDA compared to 20% survivors among those immunized in the absence of DDA. The enhanced immune response was dependent on DDA dosage and was most striking when DDA was directly complexed to the IAD-treated cells. DDA was also effective with solubilized tumor antigen and with lymphoma cells not pretreated with IAD, but the latter had to be heat killed to assure that they were nontumorigenic. In therapy experiments BALB/c mice bearing P1798 were treated with methotrexate followed by immunotherapy with IAD-P1798 alone or complexed to DDA. With two and three cycles of therapy, methotrexate alone yielded 5 and 13% survivors, while adding immunotherapy with the DDA complex gave survival rates of 63 and 71%. In the absence of DDA, chemoimmunotherapy with methotrexate and IAD-P1798 gave intermediate results. In the absence of antigen, DDA was ineffective in either immunoprophylaxis or therapy experiments.

Adjuvants, Immunologic↗

PubMed1977

Immunogenicity of solubilized tumor antigen extracted from P1798 murine lymphoma cells or isolated from tumor-bearer ascites fluid and reactivity with anti-thy-1.2 antiserum.

Solubilized antigen was prepared from P1798 lymphoma cells by sonication, 3 M KCI extraction, or isolated from the ascites fluid of syngeneic tumor-bearing BALB/c mice. Antigen was detected and quantitated by its ability to block activity of anti-P1798 serum raised in syngeneic mice, as assayed by cytotoxic and indirect immunofluorescence tests. It was established that the reaction was immunologically specific as the P1798 antigen did not inhibit the binding to L1210 lymphoma cells of antisera raised against L1210 in syngeneic DBA/2 or allogeneic BALB/c mice. Vaccination of BALB/c mice with different subcellular fractions of sonicated antigen or with ascites fluid resulted in protection against a live P1798 challenge with results comparable to those obtained using iodoacetamide-modified tumor cells. Solubilized antigen prepared by each of the three methods eluted from a Bio-Gel A5m agarose column exclusively in an early peak that had a molecular weight estimated to be greater than 2 X 10(6). This column-fractionated antigen was shown to cross-react with antiserum raised against Thy-1.2 antigen, which is present on P1798 cells. The purified P1798 antigen sedimented at 200,000 g and was shown to protect syngeneic mice in immunoprophylactic tests.

Animals↗

PubMed1977

Anti-thymocyte autoimmunity in BALB/C mice accompanying immunization to a syngeneic lymphoma.

As immunization of BALB/c mice to the syngeneic P1798 lymphoma is effected by administration of iodoacetamide-modified P1798 cells, serum antibodies appear which are reactive with P1798 and normal BALB/c thymocytes, splenocytes, and peripheral blood lymphocytes. Anti-P1798 serum also cross-reacted with thymocytes from AKR, DBA/2, and C3H mice as well as the allogeneic lymphoma 6C3HED. Anti-P1798 serum was unreactive with the Thy-1 deficient L1210 lymphoma. Multiple absorptions of anti-P1798 serum with normal BALB/c thymocytes or brain or P1798 removed antibodies to P1798 and thymocytes commensurately. Normal BALB/c liver and kidney did not absorb antibody activity. Treatment of a BALB/c splenocyte suspension with anti-Thy 1.2 serum and complement removed the population of spleen cells which were capable of reaction with anti-P1798 serum. The data suggest that antibodies to P1798 and thymocytes are the same and that specificity may be directed toward a Thy-1 related structure but without distinguishing Thy-1.1 and Thy-1.2.

Animals↗

PubMed1977

Effector cell stimulation-inhibition of in vitro lymphoma cell DNA synthesis and correlation with in vivo antitumor response.

DNA synthesis by murine lymphoma cells was stimulated up to 20-fold in vitro by syngeneic or allogeneic peritoneal cells (PEC) and peripheral blood lymphocytes, as measured by [3H]thymidine incorporation in a 44-hr assay. The increase in DNA synthesis correlated with an increase in tumor cell number in the cultures. The adherent PEC population was responsible for most of the enhancement. This effect was abrogated by pretreating the adherent cells with the metabolic inhibitors iodoacetamide, KCN, NaF, and dinitrophenol, or with glutaraldehyde, or by heating at 56 degrees. Pretreatment with mitomycin C did not eliminate the stimulatory effect. PEC supernatants did not enhance tumor growth, but effector-to-target cell proximity was shown to be necessary for stimulation. PEC from tumor-immunized mice also stimulated tumor target cell growth, but to a consistently smaller degree than did nonimmune PEC. This immune inhibition correlated with in vivo survival of mice to live tumor challenge and with ability of effector cells to increase life-span in adoptive immunity tests. Differential production of thymidine by normal and immune PEC appeared not to be a factor in these assays. Fractionation of PEC showed that the immune nonadherent cells were inhibitory in vitro and were able to increase survival time in adoptive immunity tests. On the other hand, the adherent PEC from immune mice either inhibited, stimulated, or had no effect on tumor cell DNA synthesis, compared with nonimmune adherent PEC, thus exhibiting no correlation with the immune status of the donor. In one example, administration of the macrophage activator lipopolysaccharide to mice resulted in PEC that were inhibitory in the in vitro assay, although the agent did not produce in vivo immunity. The inhibition of tumor DNA synthesis assay, with unfractionated PEC, exhibited a consistent correlation with the immune status of the host when mice were sensitized to lymphoma cells. However, the variable influence of the adherent PEC population on tumor growth reduced or nullified the immune inhibitory effect in a few cases.

Animals↗

PubMed1976

The influence of glutamine, its decomposition products, and glutaminase on the transformation of human and mouse lymphocytes.

The extent of blast transformation for human and BALB/c mouse lymphocytes has been examined over a wide range of glutamine concentrations with several agents which initiate blastogenesis. Maximum [3H] thymidine incorporation was seen at 0.5 mM glutamine for lymphoid tissues stimulated in the following manner: human and BALB/c splenic and peripheral blood lymphocytes with phytohemagglutinin, BALB/c splenic lymphocytes with lipopolysaccharide, and BALB/c vs C3H/HeJ two-way mixed lymphocyte cultures. The inhibition of blastogenesis exerted by glutamine concentrations greater than 0.5 mM could not be reversed by washing and reculturing the cells at 0.5 mM glutamine. To elucidate the reason for inhibition by higher glutamine concentrations, the products of spontaneous glutamine decomposition, L-2-pyrrolidone-5-carboxylic acid and ammonia were tested for their in vitro influence on BALB/c splenocyte blastogenesis. Pyrrolidone-carboxylic acid, in concentrations up to 5 mM, was without effect. In contrast, ammonia concentrations exceeding 1 mM became increasingly more inhibitory. The genesis of inhibitory levels of ammonia in culture medium was confirmed and has been considered as primarily responsible for inhibiton by high glutamine. Addition of Escherichia coli glutaminase (pH optimum 4.9) to cultures of BALB/c splenocytes or human peripheral blood lymphocytes had no effect on either the extent of blastogenesis of these tissues or the glutamine levels in their culture medium.

Adult↗

PubMed1976

Immunogenicity of modified tumor cells in syngenic hosts.

Modified tumor cells were used to immunize three murine hosts against syngenic ascitic lymphomas: C3H-6C3HED, BALB/c-P1798, and DBA/2-L1210. When the host was capable of a significant immune response against the malignant cells during progressive tumor growth (e.g., C3H vs. 6C3HED), protective immunization against a larger challenge tumor dose was achieved after fewer vaccinations. Lipopolysaccharide (LPS) enhanced host response to iodoacetamide (IAd) modified P1798 and L1210 so as to confer resistance after fewer immunizations with these weakly antigenic tumors. Similarities among the three systems were also seen. Modified cells may be stored at 4 degrees C several weeks and are effective when 107-108 are given i.p.; resistance appears maximal about one week after vaccination. In immunotherapy trials, C3H mice implanted with 5 x 104 6C3HED cells and treated at least four times with IAd-6C3HED demonstrated a 25% cure rate. A model was presented for evaluating parameters of response to immunotherapy in conjunction with chemotherapy. Cell-mediated immunity in resistant mice was demonstrated by inhibition of DNA synthesis in cultures of lymphoma cells and sensitized peritoneal cells (PEC) compared to that with nonimmune PEC. This assay system may also provide an opportunity for examining the hypothesis of immunostimulation of tumor growth in vitro. Humoral response to modified cells was established by membrane immunofluorescence. Although anti-6C3HED and anti-L1210 appear specific, anti-P1798 antiserum reacts with BALB/c thymocytes and murine fetal antigen.

Animals↗

PubMed1975

Endotoxin-stimulated immune response to modified lymphoma cells.

Bacterial endotoxin was administered with iodoacetamide-modified P1798 lymphoma cells to immunize syngenic BALB/cJ mice against this lymphoma to which they are naturally unresponsive. Three or four vaccinations with endotoxin (6.6 mug/injection) alone or the modified cells alone did not produce host resistance. A significant number (30 percent) of mice receiving both endotoxin and modified cells rejected a subsequent implant of viable tumor cells. Even those mice having progressive tumor growth exhibited prolonged survival. High doses of endotoxin given with the modified P1798 cells caused 70-75 percent of the mice to reject the tumor implants. When resistance developed, antibodies reacting with tumor cell membrane were demonstrable. These results indicate that B-lymphocyte stimulators can produce an effective immune response against lymphoma cells.

Animals↗

PubMed1974