Mouse CD40-transfected cell lines cannot exhibit the binding and RANTES-stimulating activity of exogenous heat shock protein 70

Here we demonstrate the inducible mouse Hsp72 binds markedly to lymphoid neoplastic macrophage-like P388D1 cells. To examine whether mouse CD40 can play a role in signaling exogenously administered HSP70 in a fashion similar to that of human CD40, we established mouse CD40-transfectants of both human 293 cells and murine-pro-B cell line Ba/F3. A small portion of mouse CD40 expressed on 293-derived transfectants was the mature form with a signal-transducible C-terminal domain, whereas a majority of expressed antigen showed the molecular size smaller than we expect. Flow cytometry showed that mouse Hsp72, but neither its deletion variants nor the related Escherichia coli DnaK, bound to the 293-derived transfectants regardless of CD40 expression. CD40 molecules expressed on the transfectants showed the binding of soluble form of CD40L but this binding was not inhibited by excess amount of HSP70. CD40L, but not any HSP70 recombinant proteins, stimulated the production of chemokine RANTES in the transfectants. Furthermore, no RANTES production was induced by HSP70-RCMLA complex in the transfectants, although it binds to 293-derived cells in a CD40-independent manner. No interaction between mouse CD40 and HSP70 recombinant proteins was detected by using the Ba/F3-derived transfectants that express the mature form of mouse CD40. The present results imply that mouse CD40 expressed on the transfectants differs from its human homolog in the binding of exogenously administered HSP70.

[Effect of bone marrow mesenchymal stem cells on acute graft versus host disease and graft versus leukemia after allogeneic bone marrow transplantation]

To investigate the effect of bone marrow mesenchymal stem cells (BMMSC) on acute graft versus host disease (aGVHD) and graft versus leukemia (GVL) after allogeneic bone marrow transplantation (allo-BMT), both bone marrow cells and BMMSC obtained after three to four weeks of culture from donor mice were transplanted into the recipient mice injected with acute lymphocytic leukemia cells 5 days before, the control group was injected with bone marrow cells alone. The survial time after allo-BMT was recorded; the general manifestation and pathological changes of aGVHD in recipient mice were observed; the effects of BMMSC on the quatity of CD4(+) and CD8(+) T cell in vivo after allo-BMT were evaluated by flow cytometry; chimerism was detected by sex chromosome. The results showed BMMSC could increase obviously the survival time, and delay onset of aGVHD, BMMSC could decrease the amount of CD4(+) T cell and increase CD8(+) T cell in vivo. It is concluded that cotransplantation of bone marrow cells with BMMSC from the same donor mice has GVL effect. BMMSC can alleviate aGVHD and maintain GVL effect after allo-BMT.

Effect of testosterone on growth of P388 leukemia cell line in vivo and in vitro. Distribution of peripheral blood T lymphocytes and cell cycle progression

In transplanted mice, the P388 tumor grew better in castrated than in non castrated (NC) mice. The proportion of CD8+ in the blood was more numerous in NC mice. The T cell subsets (CD4+ and CD8+) were also high in the mice with small tumor tissue (<10 mg). The correlation observed between the tumor weight and T cell subset in PBL and in the mice with small tumors could confirm the important intervention of CD4+ and CD8+ cells to inhibit growth of tumor. Depo-testosterone (DT) injection reduced strongly weight and tumor growth in mice. On top of that, DT administration induced a significant increase in the percentage of blood CD8+ cells in grafted mice. The effect of DT was studied on the cell cycle progression, in tumor tissue of P388 tumor bearing BDF1 mice and in P388 murine leukemia cell line in culture. The cell cycle analysis in tumor tissue showed that DT decreased both the cells in S phase and the proliferating leukemic cells, with accumulation of cells in G0/G1 phase. The testosterone can inhibit the proliferation of leukemic cells with a pharmacological dose (10(-7) M). This growth inhibition, dose and time dependent, was associated with cell cycle arrest; P388 cells accumulates in G0/G1 phase. We also observed a correlation between tumor weight and the percentage of cells in G0/G1 and the relative number of cells in proliferative state (S + G2/M). To conclude, our experiments reported that testosterone prevents the growth of tumor: indirectly by modulation of subsets T cells distribution and directly by the alteration of the cell cycle.

Antitumor activity and immune response of Mekabu fucoidan extracted from Sporophyll of Undaria pinnatifida

BACKGROUND

We showed that fucoidan, extracted from dietary seaweed, could inhibit tumor growth. However, the mechanism of Mekabu (Sporophyll of Undaria pinnatifida) fucoidan antitumor activity and how it enhances the immune response remains unknown.

MATERIALS AND METHODS

We examined the effect of Mekabu fucoidan in P-388 tumor-bearing mice and in T cell-mediated NK cell activity in normal mice.

RESULTS

The survival of mice was prolonged when Mekabu fucoidan was administered for 4 days before tumor cell inoculation, compared with non-treated mice. Fucoidan significantly enhanced the cytolytic activity of NK cells and increased the amount of IFN-gamma produced by T cells up to about 2-fold compared with non-treated mice.

CONCLUSION

The anti-tumor effect of Mekabu fucoidan appears to be mediated by IFN-gamma-activated NK cells.

Cytokine production by macrophages in association with phagocytosis of etoposide-treated P388 cells in vitro and in vivo

Chemotherapy and radiotherapy are performed for cancer patients with the hope that dying cancer cells are safely scavenged by phagocytic cells such as macrophages. In this study, we examined cytokine production by macrophages during and after the phagocytosis of etoposide-treated P388 cells in vitro and in vivo. Etoposide caused apoptosis as early as 5 h after treatment, as assessed as to the exposure of phosphatidylserine, increase in membrane permeability and DNA ladder formation. Phagocytosis by phorbol myristate acetate (PMA)-treated THP-1 cells occurred marginally when P388 cells were treated with etoposide for 10 h, while it occurred significantly with P388 cells treated for 24 h, as evidenced by flow cytometry and confocal microscopy. PMA-treated THP-1 cells produced pro-inflammatory cytokines, such as interleukin (IL)-1alpha, IL-8 and macrophage migration inhibitory factor (MIF), but not anti-inflammatory cytokines among those tested at the mRNA level during and after the phagocytosis of apoptotic cells. IL-8 and MIF were also produced at the protein level, and the IL-8 production was dependent on cell-to-cell contact when the plasma membranes of apoptotic cells were intact enough not to leak one of the cytoplasmic enzymes, lactate dehydrogenase. In addition, etoposide-treated P388 cells induced neutrophil infiltration as well as MIP-2 production upon injection into the peritoneal cavity of either normal mice or mice with sterile peritonitis. When macrophages ingesting and/or binding apoptotic P388 cells were isolated from the mice with sterile peritonitis using a cell sorter, they were found to produce MIP-2 upon culture.

Early macrophage and cytokine response during the growth of immunogenic and non-immunogenic murine tumors

Very little data exist on the mechanisms of innate immunity during the first days after syngeneic tumor inoculation. Nonspecific macrophage reaction precedes the development of specific immune response and is important for further tumor growth and stroma formation. We investigated two lymphoma cell lines of the same origin, differing in immunogenicity: non-immunogenic parental strain P388 and its highly immunogenic subline P388/adria. Early systemic inflammatory response resulted in the enhancement of nitric oxide (NO) and superoxide production by peritoneal macrophages which was at a maximum on the first day after s.c. tumor inoculation and was observed in mice bearing either of these tumors independently of immunogenicity. It was followed by a transient elevation of the serum levels of pro-inflammatory cytokines: TNF-alpha IL-6. In order to evaluate the role of inflammatory response, vaccinations with lethally irradiated lymphoma cells were performed. After two weekly injections, the mice were challenged s.c. with live tumor cells of the same subline. Effective vaccination with P388/adria lymphoma cells induced retardation of tumor growth in parallel with down-regulation of peritoneal macrophage activity and abrogation of serum cytokine release. Non-effective immunization with P388 cells influenced neither tumor growth nor macrophage functions and cytokine level. Thus, a positive correlation was found between down-regulation of the inflammatory response and inhibition of tumor growth. We suppose that, in efficiently immunized mice, special mechanisms exist which are responsible for down-regulation of the inflammatory reaction. Macrophage products may facilitate tumor cell survival by preventing apoptosis or participate in the activation of tumor neoangiogenesis. Suppression of these activities may serve as an important tool for the inhibition of tumor growth at the early stages of malignant transformation.

Protection against murine listeriosis by oral vaccination with recombinant Salmonella expressing hybrid Yersinia type III proteins

In the present study, we have investigated the possibility to engage the Yersinia outer protein E (YopE) as a carrier molecule for heterologous Ag delivery by the type III secretion system of Salmonella typhimurium. Defined secretion and translocation domains of YopE were fused to the immunodominant T cell Ags listeriolysin O and p60 of Listeria monocytogenes. In vitro experiments showed that S. typhimurium allows secretion and translocation of large hybrid YopE proteins in a type III-dependent fashion. Translocation and cytosolic delivery of these chimeric proteins into host cells, but not secretion into endosomal compartments, led to efficient MHC class I-restricted Ag presentation of listerial nonamer peptides. Mice orally vaccinated with a single dose of attenuated S. typhimurium expressing translocated hybrid YopE proteins revealed high numbers of IFN-gamma-producing cells reactive with listeriolysin O 91-99 or p60 217-225, respectively. This CD8 T cell response protected mice against a challenge with L. monocytogenes. In conclusion, these findings suggest that YopE is a versatile carrier molecule for type III-mediated foreign Ag delivery by Salmonella vaccine strains.

Graft-versus-leukemia effect and graft-versus-host disease can be differentiated by cytotoxic mechanisms in a murine model of allogeneic bone marrow transplantation

Allogeneic bone marrow transplantation (allo-BMT) is associated with both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effect. In the present study, we examined the contribution of cytotoxic effector mechanisms, which are mediated by tumor necrosis factor-alpha (TNF-alpha), Fas ligand (FasL), or perforin, to GVHD and GVL effect in a murine BMT model. Bone marrow cells plus spleen cells (BMS) from wild-type, FasL-defective, or perforin-deficient donors were transferred into lethally irradiated recipients in the parent (C57BL/6) to F1 (C57BL/6 x DBA/2) BMT model with or without prior inoculation of DBA/2 leukemia L1210 or P815 mast cytoma cells. The effect of anti-TNF-alpha antibody administration was also examined. Whereas the defect or blockade of each cytotoxic pathway could ameliorate lethal acute GVHD, the GVL effect was differentially affected. The wild-type BMS recipients died of acute GVHD within 50 days without residual leukemia cells. The FasL-defective BMS recipients showed 60%< survival over 80 days without acute GVHD or residual leukemia cells. Administration of anti-TNF-alpha antibody resulted in early leukemia relapse and the recipients died within 25 days with massive leukemia infiltration in the liver. The perforin-deficient BMS recipients died within 60 days with residual leukemia cells. These results suggest that blockade of the Fas/FasL pathway could be used for ameliorating GVHD without impairing GVL effect in allo-BMT.

Lipopolysaccharide-induced desensitization of junB gene expression in a mouse macrophage-like cell line, P388D1

Treatment of a mouse macrophage cell line, P388D1, for 1 h with bacterial LPS caused a transient increase in the level of junB mRNA expression. These cells became refractory in terms of the junB gene response to exposure to a second round of LPS or lipid A, but not to PMA. The LPS-induced desensitized state was not due to the shortening of the half-life of junB mRNA, but was suggested, by nuclear run-on analysis, to be caused by reduction of junB gene transcription. Pretreating cells with herbimycin A, a tyrosine kinase inhibitor, substantially inhibited LPS-induced expression of junB mRNA and decreased tyrosine phosphorylation of 38- to 42-kDa proteins, which comigrated with p38 and p42 mitogen-activated protein (MAP) kinases. Parallel to down-regulation of junB mRNA expression, activation of the p38 MAP kinase was markedly reduced in LPS-tolerant cells, whereas activation of p42 MAP kinase was relatively constant. The specific p38 MAP kinase inhibitor, SB202190, potently inhibited LPS-induced junB mRNA expression. These results suggest that the LPS-induced desensitization of junB gene expression occurs at or upstream of the level of gene transcription and may be involved in a defective LPS-induced p38 MAP kinase pathway.

The microtubule depolymerizing drugs nocodazole and colchicine inhibit the uptake of Listeria monocytogenes by P388D1 macrophages

Uptake of Listeria monocytogenes by different mammalian cells like macrophages and epithelial cells is dependent on functional actin filaments and hence susceptible to inhibition by cytochalasin. Here we show that phagocytic uptake of L. monocytogenes by P388D1 macrophages is also highly sensitive to treatment with the microtubule depolymerizing drugs nocodazole and colchicine. This sensitivity is cell type specific and much less pronounced in bone marrow-derived macrophages and Caco-2 epithelial cells. In contrast to nocodazole and colchicine, the microtubule stabilizing drug taxol has no significant effect on the uptake of L. monocytogenes by all three cell types tested.

Redundancy of C/EBP alpha, -beta, and -delta in supporting the lipopolysaccharide-induced transcription of IL-6 and monocyte chemoattractant protein-1

C/EBP alpha, -beta, and -delta are members of the CCAAT/enhancer binding protein family of transcriptional regulators. All three of these factors are expressed by bone marrow-derived macrophages, with the DNA binding activity of C/EBP beta and -delta increased by treatment with LPS while that of C/EBP alpha is decreased. We have ectopically expressed each C/EBP protein in P388 lymphoblasts. The expression of any of these transcription factors is sufficient to confer the LPS-inducible expression of IL-6 and monocyte chemoattractant protein-1 to lymphoblasts, which normally lack C/EBP factors and do not display LPS induction of proinflammatory cytokines. Thus, the activities of C/EBP alpha, -beta, and -delta are redundant in regard to the expression of IL-6 and monocyte chemoattractant protein-1. Since C/EBP beta-deficient mice have been reported to be largely normal in their expression of proinflammatory cytokines, it is likely that the lack of C/EBP beta is compensated for by the induction of C/EBP delta upon LPS treatment.

Tyrosine phosphorylation is required for ehrlichial internalization and replication in P388D1 cells

Replication of Ehrlichia risticii was inhibited in P388D1 cells when a protein tyrosine kinase inhibitor (genistein or herbimycin A) was added after internalization of the organism at 3 h postinfection. Upon addition of genistein at day 1, 2, 3, or 4 postinfection, further proliferation of E. risticii was prevented. The inhibition was reversible, since regrowth of E. risticii occurred upon the removal of genistein. Genistein prevented spreading of E. risticii from P388D1 cells to THP-1 cells. Genistein did not prevent binding of [35S]methionine-labeled E. risticii to P388D1 cells but did prevent internalization of [35S]methionine-labeled E. risticii. 14CO2 production from L-[14C]glutamine in Percoll density gradient-purified E. risticii was not inhibited by genistein or herbimycin A, which suggests that these reagents did not directly inhibit ehrlichial energy metabolism. Double indirect immunofluorescence labeling with antiphosphotyrosine antibody and anti-E. risticii antibody revealed colocalization of tyrosine phosphoproteins with ehrlichial inclusions. There was, however, no colocalization of phosphotyrosine with phagosomes containing 0.5-microm-diameter fluorescent beads. Western immunoblot analysis revealed that 52- and 54-kDa proteins were tyrosine phosphorylated only in infected cells and that phosphorylation of these two proteins was reduced when infected cells were treated with genistein for 6 h. These results suggest that protein tyrosine phosphorylation is specific and essential for ehrlichial internalization, replication, and spreading in macrophages but not for binding.

[Biotherapeutic efficacy of adoptive transfer of CD3AK cells in combination with cyclophosphamide and kappa-selenocarrageenan in P 388 leukemic mice]

OBJECTIVE

To study the antileukemia efficacy of a combination of adoptive transfer of CD3AK cells, cyclophosphamide (CTX), and kappa-selenocarrageenan (KSC) in P 388 leukemic mice.

METHODS

CD3AK cells in normal DBA/2 murine splenocytes were induced with anti-CD3 antibody and low dose recombinant interleukin-2 (rIL-2). The P 388 murine leukemia model was induced by i.p. injection of P 388 cells into normal DBA/2 mice. The tumor-bearing mice were administrated with adoptively transferred CD3AK Cells and/or CTX and/or KSC.

RESULTS

After tumor inoculation, the cellular immune function of P 388-bearing mice was supressed markedly. Adoptive transfer of CD3AK cells with low dose rIL-2 into the P 388 mice significantly enhanced the splenocyte proliferation (SP) induced by Con A, the NK cell activity and the splenocytic IL-2 production and prolonged their survival (45.19%); CTX (200 mg/kg) alone prolonged the survival of P 388-bearing mice (29.90%), but further decreased the immunodeficiency; combination of CTX and CD3AK passive transfer could prevent the reduction of SP, NK activity and IL-2 production in the leukemic mice and prolonged the survival (59.45%), combination of KSC and adoptively transfected CD2AK cells and/or CTX had a much better therapeutic efficacy for P 388 murine leukemia, 12.50%-75.00% of the leukemic mice were cured.

CONCLUSION

KSC is a hopeful biological response modifier in cancer biotherapy, and tumor killing effector cells and chemotherapy plus BRM might be a promising candidate for human leukemia biotherapy.

Identification, molecular cloning, biologic properties, and tissue distribution of a novel isoform of murine low-affinity IgG receptor homologous to human Fc gamma RIIB1

A cryptic splice donor site in the first intracytoplasmic (IC) exon of the murine Fc gamma RIIB gene generates a previously unknown Fc gamma RIIB isoform. Three membrane Fc gamma RIIB polypeptides of 37, 32, and 30 kDa were immunoprecipitated by Fc gamma RIIB-specific Abs, and three Fc gamma RIIB cDNAs of 1071, 987, and 930 bp were amplified by reverse transcriptase-PCR with Fc gamma RIIB-specific oligonucleotides from the mastocytoma cells P815. The 1071-bp cDNA contains all sequences of IC exons and encodes the 37-kDa Fc gamma RIIB1 isoform. The 930-bp cDNA lacks sequences of the first IC exon and encodes the 30-kDa Fc gamma RIIB2 isoform. The 987-bp cDNA has an 84-nucleotide deletion of the first IC exon 3' sequences. When stably transfected in the lymphoma B cells IIA1.6, or in the mast cells RBL-2H3, this cDNA encoded 32-kDa Fc gamma RIIB whose biologic properties were undistinguishable from those of Fc gamma RIIB1: they inhibited B cell activation when coaggregated to B cell receptors and capped when aggregated at 37 degrees C, but failed to mediate endocytosis or phagocytosis. Sequences responsible for capping and inhibition of internalization, previously assigned to sequences encoded by the first IC exon, can thus be mapped in the 19 N-terminal residues. These residues are highly conserved in human Fc gamma RIIB1. The 87-bp first IC exon of the human gene ends by a single splice site in the downstream intron and encodes a 19-amino acid insertion. The 32-kDa Fc gamma RIIB is the murine homologue of human Fc gamma RIIB1. We propose to name it Fc gamma RIIB1'. Fc gamma RIIB1' was expressed in myeloid and lymphoid cell lines, in normal spleen cells, and in resting or LPS-activated B cells.

Involvement of macrophages and cytokines into rejection mechanism of the drug-resistant and immunogenic murine lymphoma P388/adria

Macrophages and their products may exert either inhibitory or stimulatory effects on malignant cells,thus preventing or supporting tumor growth, however, the mechanisms of this interaction are not fully understood. It was the aim of the present study to elucidate the role of macrophage activation during the growth and rejection of highly immunogenic murine leukemia P388/adria cell line which was made resistant by suboptimal treatment of mice with adriablastin during the serial passaging of parental P388 cells. The functional activity of peritoneal macrophages and the serum level of cytokines IL-1 beta, IL-6 and TNF-alpha were studied in different groups of mice. Mice from group 1 (control) received saline. Mice from group 2 (tumor bearers) with fast subcutaneous (s.c) 100% tumor growth were compared with animals from group 3 that had been twice previously immunized with lethally irradiated P388/adria cells and later inoculated with viable tumor cells. Tumors grew in only 25% of group 3 animals with a significant delay. The activity of peritoneal macrophages was studied by NO2- production and the NBT-test. Both tests revealed the early high systemic activation of macrophages in group 2. This coincided with the elevation of serum TNF-alpha and IL-6 levels. This effect was not dependent on whether alive or lethally irradiated tumor cells were inoculated. The NO2- production by peritoneal macrophages correlated well with the dynamics of serum cytokine levels while the NBT-test did not. Studies on group 3 showed total abrogation of early macrophage and cytokine reactions. The production of inhibitory factors by macrophages in previously immunized mice is suggested. The fact that the early activation of macrophages and increase of serum levels of proinflammatory cytokines occurred in animals with fast growing tumors, which was decreased or absent in animals with tumor delay or rejections, allows us to suppose that this reaction plays more a supporting than a protecting role for tumor growth.

Glucocorticoid-mediated immunomodulation: hydrocortisone enhances immunosuppressive endogenous retroviral protein (p15E) expression in mouse immune cells

To define glucocorticoid (GC)-regulated genes contributing to the anti-inflammatory and immunosuppressive effects of GC, previous work from our laboratory revealed up-regulation of transcripts from endogenous type B mouse mammary tumour virus (Mtv) and type C murine leukaemia virus (Emv) loci by high dose GC treatment of P388D1 macrophage-like cells. This study demonstrates enhancement of expression from Mtv and Emv loci in P388D1 cells by more physiological hydrocortisone concentrations (1 microM), and shows direct transcriptional mode of regulation by blocking GC-mediated signal transduction at different levels. Furthermore, we found up-regulation of Emv mRNA steady-state levels in murine lymphoid lineage cells (T-like EL4 and BW5147 cells; B-like X63 cells) upon GC treatment. The Emv transcripts shown by us to be GC-up-regulated encode for the transmembrane envelope protein TM/p15E which is highly conserved in several retroviruses. TM/p15E and the p15E-like products found in humans exert immunosuppressive effects in different test systems. Thus, our findings raise the possibility that immunomodulation by GC might be mediated in part by enhanced expression of p15E(-like) products.

[A morphofunctional evaluation of the immunomodulating action of nitrosomethylurea]

The thymuses and spleens from healthy and tumor-bearing (leukemia P 388 and Lewis' carcinoma) were morphometrically studied after a single administration of the antitumor agent nitrosomethylurea in doses of 96 and 4 mg/kg. When used both in the high and low doses, nitrosomethylurea had an immunomodulating effect, causing the activation of cell-mediated immunity in healthy and tumor-bearing (in early malignancy) animals when given in the small dose.

Characterization of four drug-resistant P388 sublines: resistance/sensitivity in vivo, resistance-and proliferation-markers, immunogenicity

It was the aim of this study to compare drug-resistant sublines of the murine P388 in relation to resistance markers, the resistant phenotype and immunogenicity. Resistance to drugs either belonging to the MDR type (Doxorubicin, Vincristine, Mitoxantrone) or to the non-MDR type (Methotrexate) was generated in vivo in order to mimic the clinical situation. All resistant sublines expressed the mdr1 gene and the p-glycoprotein determined on m-RNA level or immunohistochemically, while no expression was registered in the parent P388. The rhodamine 123 fluorescence as marker for the energy dependent drug efflux pump was decreased only in the MDR-sublines, while the parent P388 and the Methotrexate-resistant line retained 100% or 90% of the dye, respectively. This indicates that the rhodamine efflux is a more function-related marker for MDR than the mdr1 gene and the pgp. The in vivo characterization of the sublines as regards their sensitivity to cytostatics revealed a clear-cut cross-resistance to MDR drugs in the MDR-lines, while the Methotrexate resistant subline was only cross-resistant to Cytarabine. In each resistant subline collateral sensitivity to certain but different cytostatics was observed. Experiments to overcome resistance by concomitant treatment with the modulators Nifedipine, Verapamil, Cyclosporin A and Chloroquin led to only limited success. The sublines P388/Mitox, P388/Vinc and P388/MTX developed immunogenicity which was never registered in the original P388. Vaccination with lethally irradiated drug-resistant cells resulted in a substantial rejection of viable tumor cells of the same line. With the P388/Mitox and P388/Vinc also an over-cross immunization was possible. This generation of immunogenicity as a concomitant characteristic of resistance should be considered as therapeutic potential also in the treatment of clinical cancer.

Antitumor immunity induced by photodynamic therapy with aluminum disulfonated phthalocyanines and laser light

Photodynamic therapy (PDT) is systemic administration of tumor localizing photosensitizers and subsequent irradiation with light of the appropriate wavelength. The combination of drug uptake in malignant tissues and selective delivery of laser-generated light provides effective therapy, with efficient tumor cytotoxicity and minimal normal tissue damage. There have been few studies of the effects of photoactivated photosensitizers on the host immune response. Since immunity is important in the control of tumor growth and spread, we have examined, in our laboratory, the effects of photoactivated phthalocyanines on the antitumor immune response. Immunosuppressed and normal mice bearing the MS-2 fibrosarcoma treated with 5 mg/kg of aluminum disulfonated phthalocyanine (AIS2Pc) and then the tumor mass exposed to laser light (100 mW/cm2 x 10 min) or treated with surgical excision of the tumor survived indefinitely, with no difference between the different groups. The survivors, tumor-free 100 days after the treatment modalities described above, were rechallenged with the parental MS-2. Some groups of surviving animals were immunosuppressed with cyclophosphamide before the injection of the tumor. Resistance to rechallenge was evidenced only in normal surviving animals cured by PDT, while the immunodepressed surviving animals and animals cured by surgery died of tumor. Finally, mice, cured by PDT and tumor-free, rechallenged with L1210 and P388 murine leukemias did not survive. These results suggest that a potential and specific 'antitumor immunity' is induced by PDT with photoactivated AIS2Pc.

Effect of various microbial preparations on P-388 mouse lymphocytic leukemia

Four bacteria-derived immunopotentiators were tested for their protective effect on a P-388 mouse lymphocytic leukemia model. The microbial test products were prepared from the following bacterial strains: ATCC 35983 Staphylococcus epidermidis isolated from a patient with IV catheter; ATCC 31874, a patented strain listed as Staphylococcus epidermidis isolated from the urine of a cancer patient; ATCC 25615 Staphylococcus hominis obtained from a child with lymphocytic leukemia, and ATCC 25614 Staphylococcus warneri, an isolate from a patient with adenocarcinoma of the breast. A limited degree of protection and prolongation in survival time was observed in the animal group treated with the bacterial strain ATCC 31874.

Differential macrophage-mediated cytotoxicity to P388 leukemia cells and its drug-resistant cells examined by a new MTT assay

After activation by interferon-gamma (INF-gamma) and lipopolysaccharide(LPS), mouse peritoneal macrophages were cocultured with P388 parental cell line (P388/PRT) and its adriamycin (ADM)-, cisplatin(CDDP)-, cyclophosphamide(CPM)-, and mitomycin-C(MMC)-resistant cell lines for one day at effector:target ratios (E:T) of 10:1, 5:1, and 2:1. The direct 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) cleavage assay and a new indirect MTT assay as well as clonogenic assay were used to quantitate activated macrophage-mediated cytotoxicity to these non-adherent leukemia targets. The results revealed that all the P388 cell lines can be suppressed efficiently by activated macrophages, but P388 CPM- and MMC-resistant cell lines (P388/CPM, P388/MMC) were more susceptible than P388/PRT while P388 ADM- and CDDP-resistant cell lines (P388/ADM, P388/CDDP) shared equal level of survival rates with P388/PRT. This study also showed that both non-activated and activated macrophages can produce formazan in a high level, which can interfere with the final results of direct MTT assay. The new indirect MTT assay can avoid such interference by separating the effectors from the targets before performing the MTT assay and reflects the real viability of the targets so the indirect MTT assay developed in this study could be a better way to examine cytostatic and cytotoxic effect of activated macrophages on non-adherent tumor cells in vitro.

Antitumor effect of Nocardia rubra cell wall skeleton on syngeneically transplanted P388 tumors

The antitumor activity of the immunomodulator, Nocardia rubra cell wall skeleton (N-CWS), was investigated using syngeneically transplanted P388 leukemia cells in a solid form. The s.c. growth of P388 tumors in DBA/2 mice was significantly suppressed by systemically administered N-CWS, and the effect was dose dependent. The antitumor effect of N-CWS was partially but significantly abrogated in splenectomized mice but not in T-cell or natural killer cell-deficient mice. Although spleen cells from mice treated with 1600 micrograms N-CWS contained no cytolytic activity, they exerted a significant cytostatic effect on P388 cell growth both in vitro and in vivo. Splenic cytostatic activity did not reside in T- or natural killer cells, but in plastic adherent cell population, macrophages. The response to N-CWS immunotherapy appeared to be associated with the number of macrophages infiltrating into the tumor lesions, and this was confirmed by histological analysis showing that P388 tumors from N-CWS-treated mice were intensively and dominantly infiltrated by macrophages. Furthermore, these were shown to be strongly tumor necrosis factor-positive by immunohistochemical analysis. These findings indicate that macrophages are the main effector cells playing a critical role in the suppression of P388 tumor growth in DBA/2 mice, and that tumor necrosis factor produced by these cells may be involved in the macrophage-mediated cytostatic effect induced by N-CWS. The fact that N-CWS suppressed the growth of weakly immunogenic P388 cells in syngeneic DBA/2 mice even when it was systemically injected would support the clinical potential of this agent.

[The preclinical assessment of the activity and pharmacological action of native human interleukin-2]

It was demonstrated in in vivo and in vitro experiments that interleukin-2, obtained by cultivation of donor lymphocytes and purified by gel filtration, induces the production of mouse and human killer lymphocytes possessing high cytolytic activity against tumor cells. Interleukin-2 does not cause irreversible changes of the physiological and morphologic indices of vital activity in mice.

Development of a mitoxantrone-resistant P 388 in vivo: approaches to overcome resistance

A normally, relatively sensitive P 388 developed resistance within few passages (P 388/Mitox) by in vivo treatment with suboptimal doses (1 mg/kg i.v.) of mitoxantrone. This resistance remained stable over 50 generations without further drug treatment. Immunization with irradiated cells (30 Gy) 7 days before tumor challenge led to partial rejection, proving that there was a higher immunogenicity of the resistant line in comparison to the parenteral P 388 line. The P 388/Mitox showed cross-resistance towards doxorubicin, daunorubicin and vincristine. Cis-DDP and bleomycin had in the resistant line significantly better antineoplastic efficacy than in the source P 388 and should be taken into consideration as second-line therapy following development of clinical mitoxantrone resistance. Nifedipine, a calcium channel blocker, and the immunosuppressive agent ciclosporin A were able to overcome resistance partially, but the mechanisms are still unclear. The P 388/Mitox can be considered as an interesting in vivo model for further research concerning resistance mechanisms and reversal of resistance.

[Studies on the possible causes of decreasing NK cell activity in tumor-bearing mice. I. The number of NK cells in the spleens of tumor-bearing mice is higher than that in normal mice]

In studies of viral immunotherapy of cancer, we found that NK cell activity in tumor-bearing mice was usually below the normal level, a universal phenomenon in tumor-bearing animals and patients. Our data show that the depressed NK cell activity in tumor-bearing mice was not due to a decrease of NK cell number. The percentage of NK cells in the spleens of tumor-bearing mice was much higher than that in normal mice. Using morphological and 3H-TdR uptake methods, we found that there were many NK blast cells in the spleens of tumor-bearing mice, and blastogenesis was sustained up to the day of death.

[Studies on the possible causes of decreasing NK cell activity in tumor-bearing mice. II. Serum and peritoneal exudate from ascitic tumor-bearing mice suppress NK cell activity]

Previous studies showed that the depressed NK cell activity in tumor-bearing mice was not due to the decrease of NK cell number. The results of this report indicate that the depressed NK cell activity in tumor-bearing mice might be due to an inhibitory factor, which probably was secreted by tumor-cells. We found that sera and peritoneal exudates from S180 or P388 tumor-bearing mice were able to inhibit the normal NK cell activity. Spleen cells incubated with the peritoneal exudate for 24 hours before assay demonstrated significantly depressed NK activity. Treatment of peritoneal exudate with a large number of spleen cells did not alter the inhibitory effect of peritoneal fluid, indicating that the inhibitory factor might not be membrane antigen shedding from the tumor cells, but may be actively secreted by them.

[Composition and immunological activity of membrane-bound surface glycoprotein from Crithidia oncopelti]

A membrane-bound glycoprotein with a molecular weight of 10000-12000 was isolated from Crithidia oncopelti and purified. The glycoprotein contained peptide, carbohydrate and lipid fragments and phosphorus. The peptide fragment was represented by 10 amino acids. The carbohydrate fragment was represented by 7 monosaccharides. The lipid part was mainly represented by stearic acid. The glycoprotein showed immunostimulating properties. It had a comitogenic effect on murine spleen cells in vitro and induced tumoricidal activity in murine peritoneal macrophages in vitro and in vivo.

[Induction of the tumoricidal activity of human and murine peritoneal macrophages under the action of antitumor chemical preparations]

Platidiam, cyclophosphamide and adriamycin induced tumoricidal activity of peritoneal macrophages from patients with disseminated ovarian carcinoma when applied in the autologous tumor cells in vitro. This effect was not observed with 10 micrograms/ml concentration of 5-fluorouracil. The mice peritoneal macrophages after incubation in vitro with 0.01-1.0 micrograms/ml of aclarubicin showed cytostatic action on syngeneic and semisyngeneic P388 cells. The peritoneal macrophages from mice treated with 2.5 mu/kg of aclarubicin intraperitoneally 1-4 days before were cytotoxic for tumor cells too.

Macrophage cell lines P388D1 and IC-21 stimulated with gamma interferon fail to inhibit the intracellular growth of Histoplasma capsulatum

Histoplasma capsulatum, a facultative intracellular parasite of macrophages, grows within mononuclear cells of the P388D1 and IC-21 cell lines with a generation time comparable to that with which it grows in normal resident peritoneal macrophages (10 +/- 2 h). Recombinant murine gamma interferon (rMuIFN-gamma) activates P388D1 cells to express la antigens but not to inhibit the intracellular growth of H. capsulatum, alone or in combination with lipopolysaccharide. IC-21 cells also could not be activated to fungistasis with rMuIFN-gamma. Explanted resident peritoneal macrophages of the C57BL/6 (from which the IC-21 cell line derives), C3H/HeJ, DBA/2 (from which the P388D1 cell line derives), A/J, and SJL/J strains of mice were all stimulated by rMuIFN-gamma to inhibit the fungus.

Fibronectin as an enhancer of nonopsonic phagocytosis of Pseudomonas aeruginosa by macrophages

Fibronectin is capable of enhancing uptake by macrophages of Pseudomonas aeruginosa grown in vivo in rats or mice or in vitro on nutrient agar plates. It was demonstrated that concentrations as low as 27 nM fibronectin produced significant enhancement of macrophage phagocytosis. Washing of fibronectin-treated macrophages did not prevent phagocytosis enhancement, but washing of fibronectin-treated bacteria did. The tetrapeptide arginine-glycine-aspartic acid-serine, which comprises the eucaryotic cell-binding domain of fibronectin, was also capable of promoting bacterial uptake, whereas the control tetrapeptide tetraglycine was not. Fibronectin caused depolarization of the mouse macrophage cell line P388D1, plasma membrane, as demonstrated by using a polarization-sensitive fluorescent probe. These data indicate that promotion by fibronectin of nonopsonic phagocytosis is mediated by the action of fibronectin on the macrophages.

Fc gamma 2b receptor-mediated phagocytosis by a murine macrophage-like cell line (P388D1) and peritoneal resident macrophages. Up-regulation by the inhibitors of phospholipase A2 and cyclooxygenase

The mechanisms of Fc gamma R-mediated phagocytosis of immune complexes were investigated by the use of a murine macrophage-like cell line (P388D1) and murine peritoneal resident macrophages. About 40 to 80% of P388D1 cells phagocytosed SRBC coated with IgG2a subclass anti-SRBC mAb (EA2a) within 60 min, whereas only 10 to 20% of the cells phagocytosed EA2b during the same period. The treatment of P388D1 cells with inhibitors of phospholipase A2 (p-bromophenacylbromide, EGTA, or dexamethasone) or of cyclooxygenase (indomethacin or aspirin) significantly promoted the Fc gamma 2bR-mediated phagocytosis of EA2b, but did not affect the Fc gamma 2aR-mediated phagocytosis of EA2a. These results suggest that the activation of phospholipase A2 activity associated with Fc gamma 2bR may lead to the inhibition of phagocytosis of EA2b. This inhibition appeared to be due to the blockade of the interaction of Fc gamma 2bR with various cytoskeletal components, because the association of Fc gamma 2bR and these cytoskeletal components, which could be eliminated by cytochalasin D, was found to be increased by the inhibition of phospholipase A2 activity.

Production and characterization of monoclonal antibodies to Fc gamma 2a-binding protein isolated from the detergent lysate of a murine macrophagelike cell line, P388D1

Hybridoma cell lines were produced by fusion of SP2/0 murine myeloma cell line with the spleen cells of Wister rats which were immunized with IgG2a-binding protein isolated from the detergent lysate of a murine macrophagelike cell line, P388D1, by affinity chromatography on IgG-Sepharose 4B. A monoclonal clone (designated as 3A2) out of a total of 13 different antibody-secreting cell lines was found to secrete IgG1 class antibodies, which inhibited more than 70% of the binding of radio-iodinated myeloma IgG2a protein to P388D1 cells. The 3A2 Fab fragments bound specifically to P388D1 cells at 4 degrees C with a KD of 1.9 x 10(-8) M and Bmax of 2.9 x 10(5) per cell. This Fab fragment also specifically bound to Fc gamma 2a receptor (R)-positive T cell line (S49) with a KD of 4.4 x 10(-9) M and a Bmax of 1.0 x 10(4) but did not bind to Fc gamma 2a-negative S49 variant cell line, cyc-. The flow cytometric analysis with the use of fluorescein-isothiocyanate-tagged 3A2 F(ab')2 also showed that this antibody binds to Fc gamma 2aR-positive cells, P388D1 and S49, but not to Fc gamma 2aR-negative cells, cyc-. Monomeric and heat-aggregated IgG2a (13-fold molar excess) inhibited the binding of the radioiodinated 3A2 F(ab')2 to P388D1 cells by 70 and 49%, respectively, whereas the inhibition by monomeric and heat-aggregated IgG2b was 17 and 39%, respectively; 3A2 F(ab')2 (100-fold molar excess) inhibited the binding of IgG2a and IgG2b to P388D1 cells by 90 and 24%, respectively, whereas the inhibition of binding of these IgG to S49 cells was 79 and 49%, respectively. Western blotting analysis showed that 3A2 antibody recognizes a major protein (Mr = 100,000) and a minor component (Mr = 80,000) separated by SDS-PAGE of P388D1 or S49 cell lysates under nonreducing condition, whereas under reducing condition, this antibody recognized a major protein (Mr = 50,000) and two additional minor components (Mr = 40,000 and 35,000). Fc gamma 2aR may thus exist at the cell surface as a disulfide linked dimer of a subunit of Mr of 50,000, which could be partially degraded during the isolation to smaller fragments of 40,000 and 35,000 Mr peptides which are still held together by interchain disulfide bond.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactions between three subpopulations of Ehrlich ascites tumor and a P388 murine leukemia in mixed solid tumors in immune competent mice

Cellular interactions between three subpopulations of Ehrlich ascites tumor and between these and the P388 murine leukemia were studied during growth of solid tumors obtained by mixtures of the cells in immune competent N/D mice. An immunogenic Ehrlich cell line (E1.15) induced an immunologically based growth inhibition of the two other Ehrlich cell lines (E1.80 and E1.95) which themselves were non-immunogenic. E1.15 was, however, unable to induce an immunological response against the P388 cell line. It is therefore suggested that when in close contact, immunologically induced cellular responses imposed by an immunogenic cell line on other cell lines require genetic and thereby close immunogenic resemblance between the cell lines. Another type of interaction was found between the E1.95 cell line and the P388 line which showed nearly identical growth characteristics as determined by tumor weight day 14, tumor growth curves, cell cycle times (per cent labelled mitoses) and cell cycle distributions (flow cytometric DNA analysis). After 2 weeks of growth of mixed P388/E1.95 tumors, flow cytometric DNA analysis on fine-needle tumor aspirates showed nearly total dominance of P388. This type of interaction required close cellular contact of viable cells, and no cellular immune response was elicited by the host animals. A third finding was that a faster growing Ehrlich cell line E1.95 dominated the tumors when inoculated in mixture with a slower growing subpopulation E1.80. This could be explained on the basis of the cell kinetic differences between these two cell lines.

Class I MHC molecules and doxorubicin resistant P388 murine leukemic cells

The major histocompatibility complex (MHC) encodes cell surface and secreted products involved in immune regulation and function. We have measured Class I MHC expression on doxorubicin (DOX) sensitive (P388/S) and resistant (P388/R84 and R84A) murine tumor cells using a monoclonal antibody to H-2d molecules. The present report shows a correlation between increased Class I MHC (H-2d) expression and drug resistance in P388 cells. Exposure of P388 cells to H-2d antibody diminished H-2d expression, whereas, treatment with murine recombinant gamma-interferon increased H-2d expression. Neither treatment significantly altered cellular DOX resistance or chemosensitivity. Thus, H-2d molecules can be used to identify DOX resistant P388 tumor cells but are probably not involved functionally in drug resistance.

Cellular basis of immunomodulation by cholera toxin in vitro with possible association to the adjuvant function in vivo

Cholera toxin (CT) is a potent oral immunogen that also acts as a strong mucosal adjuvant for immune responses to related as well as unrelated Ag. To elucidate the immunomodulating effects of CT at the cellular level we have examined interactions of CT with APC and with B and T lymphocytes in vitro. CT markedly stimulated the production of IL-1 from APC (mouse peritoneal macrophages or macrophage cell line P388D1) but did not induce Ia-Ag and had marginal, if any, effect in potentiating Ia Ag expression stimulated by rIFN-gamma on these cells. CT had differential effect on T cell proliferation in vitro, usually strongly inhibitory but on Con A-stimulated spleen cells during prolonged (greater than or equal to 5 days) culture or when added on day 4 or later to these cultures up to a two- to three-fold enhancement of proliferation was seen. CT-induced inhibition of T cell proliferation was associated with decreased production of IL-2 and anergy to exogenously added IL-2 despite apparently normal expression of IL-2R. Similar to what was found with T cells LPS-stimulated spleen B cells demonstrated both inhibition and enhancement of proliferation in the presence of CT: in high concentrations (greater than or equal to 10(-8) M) and early in culture (day 3) CT had a strong inhibitory effect on the proliferation of B cells, whereas later (day 6) and/or at lower CT concentrations (10(-9) to 10(-11) M) the proliferation was increased up to 10-fold. The net effect of CT treatment on Ig-production by LPS-stimulated spleen B cells was seen as an enhanced level of IgA and IgG but not IgM in culture supernatants. The differential effects of CT on the cells of the immune system observed in vitro may, singly or in combination, explain the immunostimulatory function of CT.

Substance P, neurokinin A, and neurokinin B induce generation of IL-1-like activity in P388D1 cells. Possible relevance to arthritic disease

Near nanomolar concentrations of substance P induce production of IL-1 or an IL-1-like activity in the mouse macrophage cell line P388D1. Moreover, this could be accomplished with the carboxyl-terminal octapeptide substance P4-11, and could be inhibited with the substance P antagonist [D-Pro2, D-Trp7,9]-substance P. Two other mammalian neurokinins, neurokinin A and neurokinin B, were also found to induce secretion of IL-1-like activity in P388D1 cells. These findings suggest that activation of immune cells by neuromodulators can contribute to the maintenance of the chronic inflammatory state and the immunopathology observed in arthritic disease mediated by IL-1. The results also suggest that one approach to the treatment of rheumatoid arthritis might be to attempt to inhibit the local effects of immuno-modulatory neuropeptides, specifically the neurokinins, in affected joints.

Serological characterization of macrophage hybridomas: identification of an interferon-gamma-inducible surface marker

Macrophage hybridoma clones prepared by fusion of splenic adherent cells with P388D1 tumor cells have previously been shown to be heterogeneous with respect to function at the clonal level. In this study the macrophage clones were phenotypically characterized by indirect RIA using a battery of rat MAbs to murine myeloid and lymphoid cell surface markers. All macrophage clones expressed the common leukocyte antigen T200 and the Mac-1 alpha and beta chains. Markers which were differentially expressed among the clones included class II antigens and the antigens detected by MAbs MIV 55, MIV 38, and 14G8. The antigens detected by the latter three MAbs were referred to as MBR-1, -2 and -3, respectively. Functional heterogeneity did not correlate with phenotypic heterogeneity among the macrophage clones. Treatment of macrophage clones with IFN-gamma resulted in a significant increase in the expression of class II antigens and induced the expression of MBR antigens on some clones which were constitutively negative for these markers. The clonal distribution and induction patterns of class II antigen as compared to MBR antigen indicated that regulation of expression of these markers was independent. In addition, the clonal distribution and induction pattern of MBR antigens, along with competitive binding studies using radiolabeled MIV 38 and 14G8 MAbs, suggested that the three MBR antigens were similar or closely associated molecules.

Passive immunization of mice with monoclonal antibodies raised against tick-borne encephalitis virus. Brief report

Adult Balb/c mice were passively immunized with monoclonal antibodies (100 micrograms/mouse) raised against tick-borne encephalitis (TBE) virus then challenged 24 hours later s.c. with 10 LD50 of TBE virus (Nëudorfl isolate). None of the mice showed evidence of premature death although all except one of the monoclonal antibodies tested are capable of enhancing the infectivity of TBE virus in the Fc receptor-bearing mouse macrophage-like cell line P 388 D 1. The ability of monoclonal antibodies to neutralize TBE virus in vitro, and to fix complement was examined, and of these properties only a single monoclonal antibody, which was able to neutralize virus, was also able to protect mice against virus challenge.

Involvement of cytotoxic T-lymphocytes in the antitumor activity of spergualin against L1210 cells

Spergualin exhibited a strong antitumor effect against L1210(IMC), a tumor cell line which has been maintained in BALB/c X DBA/2 F1 (hereafter called CD2F1) mice in the Institute of Microbial Chemistry. Mice inoculated i.p. with 10(5) cells of L1210(IMC) survived more than 60 days by daily i.p. administration of spergualin for 9 days at 5 mg/kg/day, which was started 1 day after the tumor inoculation. These cured mice rejected a second inoculation of 10(6) cells of L1210(IMC), but they did not reject the inoculation of 10(2) P388 cells. In Winn's tumor neutralization assay and in the 51Cr release assay, the T-cell fraction prepared from the spleens of the cured mice had higher cytotoxic activity against L1210(IMC) than whole spleen cells. The cytotoxic activity of spleen cells was diminished by treatment with anti-Thy-1.2 or anti-Lyt-2.1 antibody and complement. Therefore, the effector cells involved in the immunological rejection should be regarded as cytotoxic T-lymphocytes. The cytotoxic activity of these T-lymphocytes was measured during and after the spergualin administration for 9 days, and high activity was observed from 1 day after the final spergualin administration. The antitumor effect of spergualin against L1210(IMC) was much lower in T-cell-deficient athymic mice. These results suggest that cytotoxic T-lymphocytes are involved in the antitumor action of spergualin against L1210(IMC) in vivo.

OK-432-mediated augmentation of antitumor immunity and generation of cytotoxic T lymphocytes

Sensitization with mitomycin C-treated L1210 or EL-4 tumor cells followed by intraperitoneal injection of a streptococcal preparation OK-432 rendered histocompatible or syngeneic mice immune to the corresponding tumor cells. The antitumor immunity, which was more potent than that induced by attenuated tumor cells alone, was manifested by transplantation resistance to challenge tumor cells, and by cytotoxic activity of spleen cells from the primed mice. The former activity was closely related to the latter, which was found to be mainly due to tumor-specific cytotoxic T lymphocytes. The in vivo immunoaugmentation by OK-432 was susceptible to macrophage toxins such as trypan blue and carragheenins, and was partly dependent on the activity of noncytotoxic Ia-positive peritoneal macrophages. OK-432-mediated enhancement of Ia-positive macrophage functions was confirmed by concanavalin A-blastogenesis and T cell-dependent antibody formation. Allo-reactive cytotoxicity induced in allogeneic or semiallogeneic mice, which had been primed with clonogenic or attenuated tumor cells, was also augmented by concomitant administration of OK-432. These results suggest that OK-432 augments induction of antitumor immunity and alloreactive cytotoxicity, associated with stimulation of noncytotoxic Ia-positive accessory macrophage activity.

In vitro expression of secondary antitumor immunity by in vitro tumor-sensitized T cells: inhibition by tumor-induced suppressor T cells

In vitro cultivation of memory immune cells from P815- or P388-immune mice with corresponding irradiated tumor cells induced generation of cytolytic T cells (CTL). The induction of CTL generation, as well as the cytolytic activity itself, was tumor-specific. The in vitro generation of CTL from P815- or P388-immune cells was suppressed by spleen cells from mice bearing corresponding progressive tumors (tumor size 15 mm). The tumor-induced suppressor cells suppressed the in vitro generation of CTL, but did not affect their cytolytic function. The suppression was tumor-specific and was mediated by Ly1+2-L3T4+ T cells. Treatment of suppressor cell donors with cyclophosphamide or sublethal gamma-radiation completely abolished the ability of their spleen cells to inhibit the in vitro CTL generation.

Role of self carriers in the immune response and tolerance. X. A lymphoid dendritic-like tumor, P388AD.2, acts as a novel immunogenic carrier for hapten

Hapten-modified spleen cells, peritoneal exudate cells, and certain lymphoid tumors preferentially induce specific tolerance after i.v. administration. In contrast to these tolerogenic carrier cells, we found that a haptenated lymphoid dendritic-like tumor, P388AD.2, acts as a potent immunogen after i.v. injection. The immunogenicity of P388AD.2 was analyzed by measuring the specific augmentation of plaque-forming cell (PFC) responses when spleen cells from mice previously injected with haptenated tumor cells were challenged in vitro with thymus-independent antigens. Optimal immunization was found to be dependent on cell dose and hapten concentrations. Further studies indicated that P388AD.2 elicited a response which was T cell-dependent and which involved both the so-called Lyb-3,5,7- and Lyb-3,5,7+ B cell populations. Injection of haptenated tumor into different mouse strains suggested that H-2 compatibility was required to prime B cells in vivo, although significant augmentation could also be achieved in allogeneic C57B1/6J mice. The enhanced PFC responses elicited in H-2b mice could not be explained by allo-recognition of class I or II MHC determinants. In toto, these results suggest that P388AD.2 acts as a unique accessory cell for the presentation of hapten-modified self.

Clonal relationship of the lymphoblastic cell line P388 to the macrophage cell line P388D1 as evidenced by immunoglobulin gene rearrangements and expression of cell surface antigens

A lymphocytic tumor of early B cell lineage, P388, and a mature macrophage tumor, P388D1, appear to have been derived from a common precursor based on identical immunoglobulin gene rearrangements and shared cell surface antigens. These cell lines may have resulted from differential maturation of a transformed cell that is an immediate cellular precursor to both the B cell and myeloid lineages. This supports earlier findings that suggest a close relationship between early B cell and myeloid differentiation pathways.

Activation of IL 1-dependent and IL 1-independent T cell lines by calcium ionophore and phorbol ester

We have studied the activation of interleukin 1 (IL 1)-dependent and IL 1-independent T cell lines, specifically their capacity to produce and secrete interleukin 2 (IL 2). The IL 1-dependent T cell lymphoma LBRM33-1A5.47, which requires phytohemagglutinin (PHA) and IL 1 to produce IL 2, was compared with the IL 1-independent T cell lymphoma LBRM33-5A4 and T cell hybridomas DO-11.10/S4.4 and 3DO-54.8. The latter hybridomas do not require exogenous IL 1 to produce IL 2 in response to mitogens or ovalbumin (OVA)/I-Ad. Even though IL 1 is not required by these IL 1-independent T cell lines, we tested whether IL 1 could modulate their response but found no significant effect of exogenous IL 1. We then studied the activation of these T cell lines by the calcium ionophore A23187 and phorbol myristate acetate (PMA). In the case of the IL 1-dependent line LBRM33-1A5.47, there was a strong response when both A23187 and PMA were used simultaneously. We subsequently found that A23187 can replace PHA, and PMA can replace IL 1 in the activation of this cell line to IL 2 production. These observations suggest that the signal(s) provided by PHA and IL 1 involve at least in part a calcium flux, and activation of protein kinase C. Parallel experiments with the use of the IL 1-independent T cell lines showed a strong response to both agents when used simultaneously. A modest response observed to A23187 alone was always enhanced by the addition of PMA. No response was observed to PMA alone. IL 1-rich P388D1 supernatant could replace the enhancing effect of PMA in the response of the IL 1-independent T cell lines. We suggest that the activating signals provided by A23187 and PMA are at least part of the sequence of events that lead to production of IL 2 in either IL 1-dependent or IL 1-independent T cell lines. In IL 1-independent T cell lines, however, both of the activating signals studied may be delivered through stimulation of the Antigen-MHC T cell receptor.

Modulation of the immune response to tumors by a novel synthetic compound, N-[4-[(4-fluorophenyl)sulfonyl]phenyl] acetamide (CL 259,763)

CL 259,763, N-[4-[(4-fluorophenyl)sulfonyl]phenyl] acetamide, is an orally active compound capable of modifying the reactivity of certain lymphoid cell populations affected by the growth of a tumor. The compound augmented the response of lymphocytes from tumor-primed animals to syngeneic tumor cells, resulting in a marked increase in tumor cell destruction. Likewise, it enhanced macrophage inhibitory effects on the growth of tumor cells in vitro. These "activated" macrophages were detectable in peritoneal exudates of treated mice 4 to 12 days after receiving a single oral dose of CL 259,763, with peak activity being demonstrable by day 7. The compound also restored the alloreactivity of lymphocytes from immunodepressed mice bearing the Lieberman plasma cell tumor, possibly by interfering with suppressor cells. Macrophages and lymphocytes from treated mice released significantly more IL-1 and IL-2-like factors in culture than did the control counterparts. Sera from treated mice also possessed more colony stimulating factor than those from normal mice. Immunoadjuvant effects were evident when the compound was administered with an inactivated L1210 leukemia vaccine and it enhanced the effectiveness of cytotoxic chemotherapy when given to mice challenged with P388 murine leukemia. These immunomodulating effects of CL 259,763 may hopefully be exploited in efforts to augment the immune response of the host to a progressively growing tumor.

Murine cutaneous leishmaniasis: resistance correlates with the capacity to generate interferon-gamma in response to Leishmania antigens in vitro

The kinetics of cell-mediated immunity developed during the course of Leishmania major infection in resistant (C57BL/6) and susceptible (BALB/c) mice were determined by using in vitro bioassays. Cells isolated from the lymph nodes draining the infected footpads were assayed for their proliferative responses to leishmania antigens (promastigote and amastigote) or to concanavalin A (Con A). Although lymph node cells (LNC) from both mouse strains proliferated to mitogen and antigen early after infection, both C57BL/6 and BALB/c mice developed diminished in vitro proliferative reactivity within 3 to 5 wk after infection. LNC from both mouse strains recovered lymphoproliferative reactivity to Con A (week 6), but only C57BL/6 mice regained reactivity to leishmania antigens. BALB/c cells remained unresponsive to leishmania antigens throughout the subsequent course of the infection. Supernatants derived from cultures of LNC that had been stimulated with Con A or leishmania antigens were assayed for interferon-gamma (IFN-gamma) by analyzing three distinct activities associated with IFN-gamma. Culture supernatants derived from leishmania antigen stimulation of LNC from infected C57BL/6 mice, but not BALB/c mice, were able to induce surface Ia on murine P388D1 cells. Ia-inducing activity was detectable in supernatants from C57BL/6 cells as early as 3 wk, and peaked by 5 wk after infection. Although cells from infected BALB/c mice never produced detectable IFN-gamma in response to leishmania antigens, LNC from both mouse strains produced readily detectable IFN-gamma in response to Con A throughout the course of infection. Culture supernatants that induced Ia on P388D1 cells were also capable of activating resident peritoneal macrophages to display leishmanicidal activity and of inhibiting encephalomyocarditis virus replication in murine fibroblasts. Each of these activities could be removed by prior incubation of the supernatants with rabbit heterologous anti-murine IFN-gamma sera or monoclonal rat-anti-murine IFN-gamma. The correlation of healer status with the capacity to generate IFN-gamma in vitro in response to leishmania antigens was examined in BALB/c mice that had been exposed to sublethal irradiation (550 rad) before infection. These animals have been previously shown to effectively resist L. major infection. Consistent with observations in the genetically resistant C57BL/6 mice, LNC from these animals demonstrated the capacity to respond to in vitro leishmania antigen stimulation with lymphoproliferation, and more importantly, by producing IFN-gamma.(ABSTRACT TRUNCATED AT 400 WORDS)

The use of interleukin 1+ and interleukin 1- cell lines to dissociate signals involved in the induction of cytolytic T cells

The availability of paired homogeneous Ia+ tumour cell lines (P388AD, interleukin (IL)-1+, and P388NA, IL-1-), which differ in inducibility for IL-1, provided a unique opportunity to assess directly the role of Ia and IL-1 in the induction of cytolytic T cells (CTL) to trinitrophenol (TNP)-modified self. TNP-P388AD but not TNP-P388NA consistently induced H-2-restricted, hapten-specific CTL. However, in the presence of an exogenous source of IL-1, TNP-P388NA was able to induce CTL of the magnitude seen with TNP-P388AD. Both Ia expression and IL-1 secretion were necessary in that when TNP-modified purified T cells were utilized as stimulators, CTL activity was not demonstrated even if IL-1 was added, but was only seen when unmodified, P388AD, or spleen cells were added to the cultures.

Immunomodulation exerted by cyclophosphamide is not interfered by N-acetyl cysteine

Metabolism of cyclophosphamide (Cy) by liver enzymes results in cytostatic products and acrolein, which exerts urotoxicity. Experiments were designed to determine which metabolites are responsible for Cy-induced immunomodulation. For this purpose, mice were treated simultaneously with Cy and N-acetyl-cysteine (NAC), a thiol compound which reacts with acrolein, and different immunological functions were assayed. Results show that NAC did not interfere with Cy effects on antibody-dependent cellular cytotoxicity (ADCC), NK activity, delayed-type hypersensitivity (DTH) or antibody production, indicating that modulation of these functions by Cy is mediated by its cytostatic metabolites.