The immunological mouse mutants nude (nu) and rhino (hrrh) generate cytotoxic effector cells following adoptive immunotherapy but fail to reject a transplanted tumor

Adoptive immunotherapy, consisting of cyclophosphamide injection and the i.v. transfer of tumor-sensitized T cells, resulted in rejection of the immunogenic fibrosarcoma, MCA/76-9, by syngeneic C57BL/6J (B6) mice. The same treatment of tumor-bearing congenic immunodeficient mice, homozygous for the deleterious mutations nude (nu) and rhino (hrrh), did not result in tumor rejection. Paradoxically, the intratumor and intrasplenic changes taking place in each of the three strains after therapy were indistinguishable. There was an increase in Thy-1+, Ly-2+, or L3T4+ cells at the tumor site 8 days after adoptive immunotherapy and a similar increase in Thy-1+ cells in the spleen. Moreover, the T cells isolated from the tumors or spleens from each genotype were shown to be specifically cytotoxic in vitro as well as in an in vivo Winn assay. Further evidence that immune amplification had occurred in the immunological mutant mice was provided by experiments showing (a) the ability of spleen cells from tumor-bearers and those tested after therapy to produce IL-2 in response to Con A stimulation and (b) an increase in class II-MHC antigen expression by tumor-associated macrophages. The data suggest that, although amplification of antitumor immune responses occurred in the immunological mutants, the absence of a critical host factor limited the potency of the antitumor response.

Comparison of excision versus cryosurgery of an HSV-2-induced fibrosarcoma. I. Survival, extent of metastatic disease and host immunocompetence following surgery

Cryosurgery and excision were used to treat primary tumours of HSV-2-transformed hamster tumour sublines, and post-operative survival and the extent of metastatic disease were compared in the two groups. An inferior prognosis was observed following cryosurgery although the extent of metastatic disease was similar in both groups. Using this model it would appear that cryosurgery enhances the development of micrometastases rather than affecting the number of cells shed from the primary tumour during surgery. To investigate the underlying causes of the decrease in survival following cryosurgery, in vitro assays were used to monitor host immunocompetence following surgery. The results showed that whilst natural killer cell cytotoxicity was only marginally depressed, mitogen responsiveness and lymphocyte participation in a mixed lymphocyte reaction were severely reduced 3-7 days post-cryosurgery. In parallel with immunosuppression, extensive cell proliferation in the spleen of cryosurgically treated tumour-bearing animals was observed. Histological examination of the spleen demonstrated the presence of large numbers of transformed cells which correlated with the loss of mitogen responsiveness and the ability to participate in a mixed lymphocyte reaction. Further studies (manuscript submitted for publication) have demonstrated that spleen cells from animals whose tumour is treated by cryosurgery are capable of suppressing immunocompetence in vitro, implying they have a role in the uncontrolled growth of micrometastases in vivo.

Sublethal, whole-body ionizing irradiation can be tumor promotive or tumor destructive depending on the stage of development of underlying antitumor immunity

It was shown that sublethal (500 rads), whole-body gamma-irradiation of mice bearing an established i.d. immunogenic tumor can result, after several days delay, in complete tumor regression and long-term survival, but only if radiation is given after the tumor is established and growing progressively. Exposing mice to the same dose of radiation several hours after tumor cells were implanted resulted, in contrast, in enhanced growth of the primary tumor and in earlier death from systemic disease. Irradiation-induced tumor regression failed to occur in mice that were incapable of generating antitumor immunity, because of having been made T cell deficient by thymectomy and irradiation. Again, irradiation-induced tumor regression could be blocked by infusion of spleen cells from donor mice bearing a well-established tumor. These and previously published results support the view that sublethal, whole-body ionizing irradiation causes tumor regression by preferentially destroying radiosensitive suppressor T cells, thereby enabling the host to generate a therapeutic level of concomitant immunity. It is suggested that the preferential destruction of suppressor cells by irradiation depends on the acquisition, during immunologic induction, of radioresistance by antigen-activated effector T cells, and that this is the reason irradiation causes regression only of established tumors. Not all tumors tested were immunogenic enough to undergo regression in response to gamma-irradiation.

The mode of recognition of tumor antigens by noncytolytic-type antitumor T cells: role of antigen-presenting cells and their surface class I and class II H-2 molecules

The present study investigated the role of antigen-presenting cells (APC) in the activation of noncytolytic T cells against tumor antigens. The noncytolytic-type T cells exerted their antitumor effect by producing gamma-interferon (IFN-gamma) and by activating macrophages as the ultimate effectors. The production of IFN-gamma by these noncytolytic T cells following the stimulation with tumor cells required the participation of Ia+ APC, since the depletion of APC from cultures of tumor-immunized spleen cells resulted in almost complete inhibition of the IFN-gamma production. Both L3T4+ and Lyt-2+ subsets of T cells were capable of producing IFN-gamma, and the requirement of APC for the production of IFN-gamma was the case irrespective of whether noncytolytic T cells were of L3T4+ or Lyt-2+ phenotype. More importantly, it was demonstrated that the production of IFN-gamma by L3T4+ and Lyt-2+ T cells was inhibited by addition of the respective anti-class II and anti-class I H-2 antibody to cultures. These results indicate that antitumor L3T4+ or Lyt-2+ noncytolytic T cells are activated for the IFN-gamma production by recognizing tumor antigens in the context of self-class II or -class I H-2 molecules on APC.

The anti-tumour efficacy of human recombinant interleukin 2. Correlation between sensitivity of tumours to the cytolytic effect of LAK cells in vitro and their susceptibility to interleukin 2 immunotherapy in vivo

Experiments were designed to test what percentage of experimental MC-induced murine sarcomas were sensitive to the local tumour inhibitory effect of IL-2 and whether any correlation existed between the sensitivity of these sarcomas to the immunotherapeutic effect of IL-2 and their susceptibility to the cytolytic effect of IL-2-activated killer cells. It was found that the sensitivity of MC-induced sarcomas to local IL-2 immunotherapy was a general phenomenon. Repeated peri-tumoural injections of RIL-2 inhibited the growth of five (MC11, MC13, MC14, MC15, MC16) out of six sarcomas in syngeneic mice. The sixth murine sarcoma (MC12) was found to be resistant to the tumour inhibitory effect of IL-2. Similarly, five (MC11, MC13, MC14, MC15, MC16) out of six murine sarcoma cell lines were sensitive to the cytolytic effect of IL-2-activated syngeneic killer spleen cells when examined in vitro, whereas the sixth (MC12) sarcoma cell line was resistant. These results suggest that LAK cells represent the effector cell mechanism responsible for the anti-tumour efficacy of local IL-2 immunotherapy and that in vitro testing of sensitivity to the LAK cell-mediated cytolysis may be used to detect tumours responding to IL-2 immunotherapy in vivo.

Enhancement of interleukin-2 release in rats by treatment with bleomycin and adriamycin in vivo

Spleen cells from rats previously injected with bleomycin (10 mg/kg) or Adriamycin (1 mg/kg) were able to release higher levels of interleukin-2 (IL-2) than cells from untreated animals. The difference in IL-2 release was detected after the cells were exposed to a suboptimal dose of concanavalin A (0.5 micrograms/ml) for 24 h. By cytofluorimetry, these drugs did not change the proportion of W3/25+ (helper) or OX-8+ (suppressor) T-cell subsets. In contrast, the immunosuppressive drug cyclophosphamide inhibited the IL-2 release from spleen cells under the same conditions. It is suggested that some anti-cancer antibiotics may be able to enhance the release of IL-2 while other cytotoxic drugs with more immunosuppressive potential could inhibit the release of this mediator.

In vitro and in vivo release of cytostatic factors from Lactobacillus casei-elicited peritoneal macrophages after stimulation with tumor cells and immunostimulants

The effect of tumor cells and immunostimulants on the release of cytostatic factors (CF) from Lactobacillus casei YIT 9018 (LC)-, Corynebacterium parvum (CP)- or peptone-elicited peritoneal macrophages (PM) was investigated in vitro and in vivo. Significant release of CF into the culture medium from PM elicited with LC was induced by seven of eight mitomycin C-pretreated tumor cell lines and not by normal spleen cells, while no CF was released extracellularly from peptone-elicited PM given the same stimulus. CF were released from LC-elicited PM (LCEPM) after stimulation with LC, bacille Calmette-Guérin, streptococcal preparation OK-432, fucoidan or lipopolysaccharide, and LC but not CP induced CF production in the peritoneal cavities of LC- or CP-primed mice. The release of CF from LCEPM after stimulation with mitomycin C-pretreated 3T12-3 cells was inhibited by D-mannose and not by L-fucose. L-Rhamnose and mannose 6-phosphate, but not D-mannose or L-fucose, caused the release of CF from the PM. It was suggested that the release of CF from activated PM is caused by stimulation by some tumor cells, sugars, or bacterial immunostimulants, D-Mannose and L-rhamnose on the surface of tumor cells or bacteria, respectively, may plan an important role in the release of CF from activated macrophages.

Studies on the recovery from tolerance to tumor antigens. I. Bone marrow cells from tolerant hosts are not rendered tolerant, but provide potential to reconstitute tumor-specific effector T cell clones

The present study investigates the potential of bone marrow cells from mice tolerant to tumor antigens to repopulate tumor-specific effector T cells. C3H/He mice were inoculated i.v. with 10(6) 10,000 R X-irradiated syngeneic X5563 plasmacytoma tumor cells three times at 4-day intervals. This regimen abrogated the ability of spleen cells from these mice to develop anti-X5563 cytotoxic and in vivo protective (tumor-neutralizing) T cell-mediated immunity as induced by i.d. inoculation of viable X5563 cells followed by surgical resection of the tumor. Since such suppression was induced in a tumor-specific way, this represented a state of antitumor tolerance. When bone marrow cells from normal or X5563-tolerant mice were transferred i.v. into 950 R X-irradiated syngeneic C3H/He mice, both groups of recipient mice generated anti-X5563 tumor immunity over a similar time course and to almost the same degree. Anti-X5563 tumor immunity induced in (C3H/He X C57BL/6) F1 mice which had been transferred with bone marrow cells from normal or X5563-tolerant C3H/He mice were mediated by T cells expressing the Ly phenotype of C3H/He, but not of C57BL/6, excluding the possibility that the antitumor effector cells were derived from recipient mice. It was also demonstrated that C3H/He mice which had been reconstituted with normal marrow were rendered tolerant when the tolerance regimen was started 7 weeks, but not 1 week after the bone marrow reconstitution. These results indicate that bone marrow cells from antitumor tolerant mice are not rendered tolerant to the tumor but can provide the potential to repopulate antitumor CTL and in vivo protective effector T cells.

Defective T helper activity in the spleen of BALB/c mice immune to a syngeneic fibrosarcoma

BALB/c mice were immunized with the syngeneic 3-methylcholanthrene-induced fibrosarcoma CA-2 by the growth and excision method. When lymphoid cells from different organs of these tumor-free mice were tested in a direct 51Cr-release assay, peritoneal exudate cells but not spleen cells displayed specific cytotoxicity against the syngeneic tumor target. A cytotoxic response could be obtained by tumor-immune spleen cells when cultured in a mixed lymphocyte tumor cell culture (MLTC) at high but not low density although at the same effector/stimulator ratio. Lack of cytotoxic activity in low density MLTC was not due to an impairment of cytotoxic precursors since cytotoxicity was rescued by adding exogenous interleukin-2 in experimental conditions in which no lymphokine-activated killer cells could develop relevant anti-CA-2 lysis. When low density MLTC were supplemented with either 800 R-irradiated cells or nonirradiated, negatively selected Lyt 1+ cells from the same immune mice, induction of a cytotoxic response against CA-2 occurred and interleukin-2 production became detectable. Additional studies indicated that spleen cells of CA-2-immune mice were also impaired in their ability to provide help to syngeneic thymocytes for the generation of cytotoxic T lymphocytes against C57BL/6J alloantigens. Dilution effect of helper cells due to immunization procedures was excluded since spleen cells of mice immunized against another BALB/c tumor, the YC8 lymphoma, or against DBA/2 minor histocompatibility antigens provided good help to thymocytes against the same alloantigens. These results indicate that tumor-immune animals may also have selective T helper defects in an important lymphoid organ like spleen.

Cultivation of avian rotaviruses in chicken lymphocytes and lymphoblastoid cell lines

Avian rotavirus isolates were used to infect normal chicken spleen cells, lymphoblastoid T cell lines transformed by Marek's disease virus, an avian leukosis virus-transformed B cell line, and a reticuloendotheliosis virus-transformed line, which is a pre-B, pre-T cell line. All five isolates tested were able to infect spleen cells and the three types of lymphoblastoid cell lines, suggesting that avian rotaviruses can infect both B and T cells. Splenic lymphocytes were considerably less susceptible to infection than chick kidney cells. Lymphoblastoid cell lines remained virus-positive during a 10-day culture period. Virus was neutralized by the addition of low dilutions of normal chicken serum and high dilutions of chicken anti-rotavirus serum.

Adoptive immunity in mice challenged with L1210/DTIC clones

New antigenic specificities, not detectable on parental cells, have been induced by many investigators in mouse lymphomas by treatment with the antitumor agent 5(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC). The antigens are transmissible, after withdrawal of the drug treatment, as an inheritable character. The mechanism of induction, the molecular nature, and the number of the new antigenic specificities have not been completely elucidated. Four clones from murine leukemia L1210 isolated and expanded in vitro were treated in vivo with DTIC and the new sublines were studied in detail. The four drug-treated sublines studied exhibited strong immunogenicity since they were rejected by syngeneic animals. Immunosuppressed animals challenged with 10(7) A/DTIC or P/DTIC cells were reciprocally protected by the adoptive transfer of spleen cells from donors that had rejected a lethal challenge of A/DTIC or P/DTIC clone. In a similar fashion, the adoptive transfer of spleen cells obtained from animals that had rejected the Q/DTIC or the R/DTIC clones protected immunosuppressed mice challenged with Q/DTIC or R/DTIC cells. No antitumor activity was observed in cross-protective schedules other than those indicated. It was been concluded that (a) the L1210 leukemia line does not have antigenic cells, (b) four DTIC-treated clone sublines were rejected by compatible hosts, and (c) two mutually exclusive sets of antigens were expressed in four antigenic clone sublines.

Induction of activated natural killer cells from murine spleen cells primed in vivo and subsequently challenged in vitro with the streptococcal preparation OK432

The present study shows that natural killer cell-mediated cytotoxicity of BALB/c mouse spleen cells to syngeneic tumor cells was augmented by in vivo priming or in vitro stimulation with the streptococcal preparation OK432. The augmentation of spleen cell cytotoxicity to syngeneic tumor cells by in vivo priming alone with OK432 was lower than that obtained by in vitro stimulation alone with OK432. When the murine spleen cells primed in vivo with OK432 were rechallenged in vitro with OK432 at various intervals, the natural cytotoxicity was more strongly enhanced than that seen with in vitro stimulation alone. The cell surface phenotype of killer cells activated with OK432 was Thy 1+ and asialo GM1+, suggesting the activated natural killer cell. Next, mice were transplanted with syngeneic colon adenocarcinoma cells, and primed in vivo with OK432. These spleen cells were subsequently challenged in vitro with OK432. These spleen cells displayed a strong cytotoxic activity not only to the transplanted adenocarcinoma cells but also to other syngeneic tumor cells.

Mechanism(s) of in vitro macrophage activation with Nocardia rubra cell wall skeleton: the effects on macrophage activating factor production by lymphocytes

BALB/c mouse peritoneal macrophages prepared from WPC which had been treated with N. CWS demonstrated potent cytostatic activity against syngeneic Meth A fibrosarcoma cells. The maximum cytostatic activity developed in the macrophages when WPC were incubated with 25 micrograms/ml N. CWS for 3 days. NAPC from BALB/c mice given an i.p. injection with 100 micrograms N. CWS 7 days previously (N. CWS-NAPC) or supernatants from N. CWS-NAPC also activated peritoneal macrophages in vitro. However, when peritoneal macrophages were incubated with N. CWS in the absence of NAPC, or when T cells were depleted from WPC by treatment with anti-Thy 1.2 antibody and complement, N. CWS failed to enhance the cytostatic activity of the macrophages. Furthermore, thioglycollate-elicited peritoneal macrophages from C3H/HeN mice increased their cytolytic properties by incubation with supernatant fluids from N. CWS-treated spleen cells. These findings suggest that in vitro macrophage activation with N. CWS depends on MAF secreted from T lymphocytes.

Specificity of the generation and expression of enhanced anti-plasmacytoma immunity by spleen cells from melphalan-treated MOPC-315 tumor bearers

We have shown previously that low-dose melphalan (L-PAM) therapy of mice bearing a large MOPC-315 plasmacytoma enables their hitherto immunosuppressed spleen cells to exert potent anti-MOPC-315 cytotoxicity following in vitro immunization with MOPC-315 tumor cells. Here we show that, following in vitro immunization with MOPC-315 tumor cells, spleen cells from such L-PAM-treated MOPC-315 tumor bearers exhibited enhanced T-cell-mediated cytotoxicity not only against the MOPC-315 tumor, but also against another plasmacytoma (MOPC-104E) possessing surface immunoglobulin (SIg) of a different idiotype than the MOPC-315 cells, as well as against a variant of the MOPC-315 tumor which does not produce nor possess SIg (SIg- MOPC-315). The enhanced cytotoxicity was directed against target antigens which are not expressed on the surface of the syngeneic WEHI 22.1 thymoma or the natural killer-sensitive YAC-1 cells. Plasmacytoma shared antigens, other than immunoglobulins, were able to stimulate spleen cells from L-PAM-cured MOPC-315 tumor bearers to generate in vitro a secondary type anti-plasmacytoma cytotoxic response. L-PAM-cured MOPC-315 tumor bearers exhibited in vivo immunity against SIg- MOPC-315 tumor cells, which was sufficiently triggered by the SIg- cells to bring about the rejection of a challenge of at least 100-fold the minimal lethal tumor dose of the SIg- MOPC-315 cells. Thus, SIg- MOPC-315 tumor cells present among SIg+ tumor cells in the parental MOPC-315 tumor inoculum can be eradicated in the L-PAM-treated MOPC-315 tumor bearers by the immune response to SIg+ tumor cells as well as by the immune response to SIg- tumor cells themselves.

Mouse cytomegalovirus is infectious for rats and alters lymphocyte subsets and spleen cell proliferation

The Smith strain of mouse cytomegalovirus (MCMV) was infectious for infant and mature DA strain laboratory rats as judged by development of neutralizing antibodies and specific spleen cell proliferation on stimulation with MCMV antigen. An i.p. inoculum of 10(6) PFU of MCMV was fatal for more than two-thirds of infant mice (1-7 days of age), and disseminated viral infection was documented by isolation of virus from body organs. In contrast, weanling and adult rats did not become ill as a result of infection with a larger inoculum of 10(7) PFU. However, these older MCMV infected rats did show transient reversals of T helper/suppressor cell ratios and alterations of immune cell function as detected by in vitro spleen cell proliferation assays. Seven days after MCMV infection, there was a generalized increase in 3H-thymidine incorporation by spleen cells in both resting (unstimulated) cultures and cultures exposed to mitogens (Con A, PHA, LPS) and to MCMV antigen. At 14 days, the spleen cell proliferation in the unstimulated cultures returned to normal but was depressed compared to controls in response to Con A. These observations show that laboratory rats are susceptible to MCMV infection and that asymptomatic infection may occur and cause transient alterations in lymphocyte subsets and in their reactivity to mitogens.

The difference between 5-fluorouracil and melphalan in their ability to promote antitumor immune response against MOPC-315 plasmacytoma

The anticancer chemotherapeutic drugs melphalan (L-phenylalanine mustard; L-PAM), 5-fluorouracil (5-FU), methotrexate (MTX), and daunorubicin (DAU) were tested for their toxic activity against MOPC-315 tumor cells in vitro. L-PAM, 5-FU, and DAU had a marked toxic effect whereas MTX did not affect the rate of thymidine incorporation in the tumor cells. L-PAM (7.5 mg/kg) induced permanent regression of large s.c. MOPC-315 plasmacytoma tumors, 5-FU (200-250 mg/kg) induced transient regression of MOPC-315 tumors with reappearance starting on the 6th day after the 5-FU injection and DAU (5 mg/kg) was not effective. L-PAM treatment restored the cytotoxic potential of spleen cells of tumor-bearing mice against target MOPC-315 tumor cells whereas spleen cells from tumor-bearing mice treated with 5-FU were unable to mount a cytotoxic response. L-PAM and 5-FU were also assayed for their effect in vitro on induction of suppressor T cells by ConA. L-PAM treatment in vitro markedly reduced the induction of suppressor T cells by ConA whereas 5-FU had no effect. It is suggested that anticancer chemotherapeutic drugs can be classified in "immunopromoting" (L-PAM as prototype) and "nonimmunopromoting" (5-FU as prototype) on the basis of their effect in vivo on established tumors and their effect on induction of suppressor T cells by ConA.

Immunoregulating activity of tumor-associated macrophages

In this report, we examine the antigen nonspecific immunoregulating activity of macrophages isolated from the murine methylcholanthrene-induced fibrosarcoma FSA. These cells were shown to enhance the primary anti-CRBC PFC response of whole normal spleen cells in a dose-dependent fashion. This function was associated with a subpopulation of large Ia-negative macrophages and was mediated by a soluble macrophage-derived factor that appeared to act by stimulating the proliferation and/or differentiation of antigen-reactive T cells. The relationship of this factor to previously described monokines is discussed.

The Lyt phenotype of the T cells responsible for in vivo tumor rejection in syngeneic mice

Spleen cells of BALB/c mice hyperimmunized with a transplantable methylcholanthrene-induced sarcoma Meth A (Meth A-Im-SPL) inhibited the growth of Meth A tumor in vivo in a tumor neutralizing test. Meth A-Im-SPL did not neutralize another antigenically distinct sarcoma, Meth 1, indicating that the antitumor activity is tumor specific. Lyt-1+2- cells of Meth A-Im-SPL (Im-Lyt-1+2-) were the effectors since in vitro treatment of Meth A-Im-SPL with anti-Thy 1.2 or anti-Lyt 1.2 antibody plus complement completely abrogated their neutralizing activity, whereas treatment with anti-Lyt 2.2 plus complement did not. To further confirm the effector activity of Im-Lyt-1+2- cells, T cell subpopulations were separated from Meth A-Im-SPL by the panning method. The purified Im-Lyt-1+2-, but not Im-Lyt-1+2+ cells neutralized the tumor in athymic nu/nu mice as efficiently as in +/+ mice, suggesting that the donor Im-Lyt-1+2- cells but not recipient T cells were primarily responsible for neutralizing the tumor. The present study, however, did not exclude the possible contribution of recipient T cells to the tumor neutralization and this is open to further investigation.

The augmentation of tumor-specific immunity by virus help. III. Enhanced generation of tumor-specific Lyt-1+2- T cells is responsible for augmented tumor immunity in vivo

The role of vaccinia virus-reactive helper T cells (Th) in augmenting in vivo generation of antitumor protective immunity and the Ly phenotype mediating the enhanced in vivo tumor immunity were investigated. C3H/HeN mice were inoculated i.p. with viable vaccinia virus to generate vaccinia virus-reactive Th activity. The mice were subsequently immunized i.p. with virus-infected syngeneic X5563 and MH134 tumor cells, and spleen cells from these mice were tested for in vivo tumor neutralizing activity. Immunization of virus-primed mice with virus-uninfected tumor cells and of virus-unprimed mice with virus-infected tumor cells failed to result in in vivo protective immunity. In contrast, spleen cells from mice immunized with virus-infected tumor cells subsequent to virus-priming exhibited potent tumor-specific neutralizing activities. Such an augmented generation of in vivo protective immunity was accompanied by enhanced induction of tumor-specific cytotoxic T lymphocyte (CTL) and antibody activities in X5563 and MH134 tumor systems, respectively. However, analysis of the effector cell type responsible for in vivo tumor neutralization revealed that enhanced in vivo immunity was mediated by Lyt-1+2- T cells in both tumor systems. Moreover, the Lyt-1+2- T cells exerted their function in vivo under conditions in which anti-X5563 tumor-specific CTL or anti-MH134 tumor-specific antibody activity was not detected in recipient mice. These results indicate that augmenting the generation of a tumor-specific Lyt-1+2- T cell population is essential for enhanced tumor-specific immunity in vivo.

Immunopotentiator separated from hot water extract of the seed of Benincasa cerifera Savi (Tohgashi)

The separation and properties of a new immuno-potentiator, Benincasa cerifera mitogen (BCM) fraction, were investigated. BCM fraction was separated from hot water extract of the seed of Benincasa cerifera Savi (Tohgashi) by gel filtration using Sepharose 4B. BCM fraction is a heteropolymer consisting of uronic acid, neutral sugars, protein, and phosphorus. The proliferation and differentiation of murine B cells were markedly stimulated by BCM fraction. The in vitro development of peritoneal macrophages into antitumor macrophages was also activated by the addition of BCM fraction to cultures. BCM fraction augmented the IgM and IgG antibody responses against sheep erythrocytes (SRBC) and the induction of delayed-type footpad reaction against SRBC. The antitumor activity of BCM fraction was observed in terms of prolongation of the survival period of mice bearing Meth A fibrosarcoma. After hydrolysis with 1% acetic acid at 100 degrees C for 4 h, marked mitogenic activity was found in a precipitate composed of 29% neutral sugars, 50% uronic acid, 1% protein, and 0.1% phosphorus. The precipitate did not contain detectable amino sugar. The possibility that the biological activities of BCM fraction may be due to contamination by bacterial lipopolysaccharide was ruled out on the basis of the results of chemical analysis and of marked mitogenicity noted in C3H/HeJ spleen cell cultures.

Effect of melphalan in vitro on induction of murine suppressor T cells by ConA

The effect of treatment with melphalan in vitro on the activity of spleen cells from BALB/c mice was investigated. Incubation of spleen cells with 1.5-5 micrograms melphalan/1 X 10(7) inhibited subsequent mitogenic stimulation by ConA or PHA and the allogeneic response of BALB/c spleen cells against C57B1 target spleen cells. Incubation of spleen cells with ConA led to induction of suppressor T cells which when added to fresh cultures inhibited the allogeneic response. Preincubation of spleen cells with melphalan even at low concentrations (0.15-0.5 micrograms 1 X 10(7) cells) which do not directly affect mitogenic stimulation or allogeneic response partially inhibited the generation of suppressor T cells by ConA. Treatment with melphalan had no effect on already induced suppressor T cells as shown by incubation of spleen cells with melphalan (0.15-5 micrograms/1 X 10(7) cells) after incubation with ConA. Addition of cells treated with melphalan alone (without ConA) to fresh cultures led to an increase in the allogeneic response.

Effects of the removal of adherent and phagocytic cells on the spleen cell lymphoproliferative response of tumor-bearing mice

Cell-mediated immunity was investigated in two BALB/c mouse tumor systems using the lymphoblastogenesis test with phytohemagglutinin as the mitogen. This lymphoproliferative response was quantitated using the Stimulation Index (SI). There was little evidence for suppressor cell activity in cell mixing experiments in which spleen cells from #51 cell-injected mice were mixed with spleen cells from normal mice. Following macrophage removal by Sephadex G-10 columns and carbonyl iron ingestion, there were no significant changes in the SI values for spleen cells from the #51 cell-injected mice. In contrast, spleen cells from mice injected with H238 cells, a herpes virus-transformed cell line, had a significantly lower SI value than that of normal mice. Suppressor cell activity was demonstrated in cell mixing experiments in which spleen cells from H238 cell-injected mice were mixed with normal spleen cells. Removal of adherent cells from spleen cells from H238 cell-injected mice by Sephadex G-10 columns restored the SI value to that of normal mice. An increased SI value was also seen after removal of phagocytic cells by carbonyl iron. These results suggested that cells with the functional properties of macrophages played an important part in the immunosuppression observed in the H238 tumor system. Comparison of the two macrophage depletion methods suggested that another cell population was also involved in the suppressive effect. Results of immunofluorescent techniques with anti-Lyt-1 and anti-Lyt-2 monoclonal antibodies show these cells to be Ly 1-, Ly 2,3+ phenotypes of T-lymphocytes.

Tumour necrosis factor and the lysosomal enzymes of macrophages or macrophage-like cell line

The relationship between tumour necrosis factor (TNF) and macrophages or macrophage-like cell line, especially the lysosomal enzymes was investigated. The serum lysosomal enzymes and LDH activities were increased in proportion to the TNF production even in different strains of mice. Lysosomal enzymes and TNF activity were released into the supernatant of the culture medium of macrophage-enriched peritoneal exudate cells (PEC) or spleen cells derived from Propionibacterium acnes-primed mice after addition of lipopolysaccharide (LPS). After passage through a Sephadex G-10 column, TNF activity could not be detected in the supernatant of these spleen cells after addition of LPS. Also TNF activity could not be detected in the supernatant following destruction of PEC. These results suggest that TNF producibility is strongly related to the degree of activation of macrophages, especially the lysosomal enzymes. The murine macrophage-like cell line, J774, also released TNF activity and lysosomal enzymes after addition of LPS.

Effect of a thymic factor, thymostimulin, on growth and pulmonary metastases of Lewis lung carcinoma

The antitumor and antimetastatic activities of a thymic factor, thymostimulin (TP-1), with or without cyclophosphamide (CPA) were examined in C57BL/6 mice inoculated with Lewis lung carcinoma (3LL). Tumor growth was followed by determining the tumor diameter after tumor implantation. TP-1 given to mice every 2 days after tumor implantation significantly inhibited tumor growth without affecting the survival rate. For induction of spontaneous pulmonary metastases, 3LL cells were implanted into the footpads of mice, and the implanted tumor was removed on day 9. The antimetastatic effect of TP-1 on pulmonary metastases after removal of the primary tumor was evaluated by counting the number of pulmonary surface nodules. TP-1 showed antimetastatic activity depending on its time of administration and dose. Combined therapy with TP-1 plus CPA significantly prolonged the survival of mice with pulmonary metastases. The cytolytic activities of spleen cells on 3LL cells were enhanced in mice treated with TP-1 and/or CPA and the cytolytic activity of nonadherent spleen cells, the T-cell population, was enhanced. The role of cytolytic spleen cells in inhibiting and preventing metastases was discussed.

Monoclonal antibodies to antigens associated with transitional cell carcinoma of the human urinary bladder. I. Determination of the selectivity of six antibodies by cell ELISA and immunofluorescence

Spleen cells from BALB/c mice immunized with cells derived from transitional cell carcinomas (TCC) of the human urinary bladder were fused with mouse myeloma Sp 2/0 Ag14 cells. Monoclonal antibodies from six established hybridomas were investigated for specificity in a cell ELISA and in indirect immunofluorescence against a large panel of fixed intact cells. Three of the antibodies reacted with half or more of the eight bladder tumors and with a few unrelated tumors. They did not react at all with malignant or normal cells of hematopoietic origin. A fourth antibody reacted with seven of eight bladder tumors. It also reacted weakly with a prostatic carcinoma, with five of six malignant or transformed B cell lines, and with a subpopulation of normal lymphocytes, but not with any of the other cells on the test panel. These four antibodies did not react with cells derived from normal urothelium. The results suggest that these antibodies might recognize cell-type-restricted antigens associated with malignancy. Another antibody reacted with almost all urothelium-derived cells. It also reacted with three of three melanomas but not with any other cells on the panel. The sixth antibody reacted with 32 of the 37 cells tested. The spectrum of reactivities displayed by the antibody suggested that it recognizes HLA antigens.