Rachel Ophir

Thymic Humoral Factor-γ2 (Thf-γ2) Immunotherapy Reduces the Metastatic Load and Restores Immunocompetence in 3LL Tumor-Bearing Mice Receiving Anticancer Chemotherapy

AbstractIn mice bearing immunogenic tumors, adding thymic humoral factor-γ2 (THF-γ2)1 immunotherapy as an adjunct to anticancer chemotherapeutic regimens not only potentiates the antitumor activity of each drug but also repairs tumor/chemotherapy-induced damage to T-cell populations and functions. The Lewis lung carcinoma (3LL) is a weakly immunogenic, highly metastatic tumor in C57BL/6 mice. To investigate whether the immunoregulatory octapeptide is also effective against a tumor that does not elicit an antitumor immune response, we assessed the effect of combination THF-γ2 immunotherapy and chemotherapy in 3LL-bearing mice. The results indicate that THF-γ2 combined with either Melphalan or 5-Fluorouracil was more effective in reducing metastatic load than either chemotherapeutic drug alone and was characterized by massive infiltration of lymphatic cells. The combined chemoimmunotherapy treatment also prolonged the survival time in all treated animals and repaired T-cell defects and impaired in vitro cel...

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

SummaryThe 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 protoype) on the basis of their effect in vivo on established tumors and their effect on induction of suppressor T cells by ConA.

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

SummaryThe 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 μg melphalan/1×107 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 μg 1×107 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 μg/1×107 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.

THF-γ2, a thymic hormone, increases immunocompetence and survival in 5-fluorouracil-treated mice bearing MOPC-315 plasmacytoma

SummaryThe effect of the thymic hormone, THF-γ2, on the immunocompetence of 5-fluorouracil (5-FU)-treated BALB/c mice, bearing MOPC-315 tumor, was examined. Treatment of noninoculated or tumor-bearing mice with THF-γ2 after 5-FU injection, resulted in an increase in the antibody response to sheep red blood cells and in the allogeneic response in spleen cell cultures and had no effect on the concanavalin-A-induced interleukin-2 secretion beyond that caused by 5-FU alone. Treatment with either 5-FU alone or 5-FU and THF-γ2 resulted in restoration to normal values of Lytl- and L3T4-positive populations in tumor-bearing mice. THF-γ2 prolonged the survival time of mice bearing MOPC-315 tumor beyond that observed in mice treated with 5-FU alone.

Deficiency in immunocompetence of mice cured from large MOPC-315 plasmacytomas by melphalan therapy

SummaryMice cured from large MOPC-315 tumors by a single dose of melphalan, 7.5 mg/kg, were examined for up to 60 days after the drug treatment (71 days after the tumor inoculation) for their ability to respond to mitogenic stimulation, specific and nonspecific antigenic stimulation and for their susceptibility to inoculation with an unrelated tumor, L10 lymphoma. The response of spleen cells from cured mice to mitogenic stimulation by phytohemagglutinin or concanavalin A was slightly depressed at an early stage after the drug treatment. The allogeneic response against C57BL spleen cells and the antibody response against sheep red blood cells (SRBC) of spleen cells from cured mice remained below normal levels during the whole observation period. The deficiency in response to antigenic stimulation was found to be due to impairment in T-cell function. Cured mice were also deficient in their response to SRBC immunization (antibody and delayed-type hypersensitivity responses) and were more susceptible to inoculation with an unrelated tumor, L10 lymphoma, than normal, noninoculated mice. On the other hand, spleen cells of cured mice developed a highly specific cytotoxic response against target MOPC-315 tumor cells and the cured mice were resistant to challenge with an otherwise highly tumorigenic dose of MOPC-315. Thus, cured mice remained deficient for a long period of time in their response to MOPC-315-unrelated antigens but, at the same time, they showed a potent specific antitumor immunity potential in vivo and in vitro.

THF-γ2-mediated reduction of pulmonary metastases and augmentation of immunocompetence in C57BL/6 mice bearing B16-melanoma

Immunotherapy with the immunomodulating thymic humoral factor-gamma 2 (THF-gamma 2) octapeptide, combined with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) chemotherapy, will be used for enhancing host immune response to arrest pulmonary metastases of a B16-F10.9 melanoma tumor. In this experimental model of pulmonary metastasis, the highly metastatic B16-F10.9 melanoma tumor cells (2 x 10(5)) were inoculated into the footpad of mice to form a primary tumor. The tumor-bearing leg was surgically removed on reaching the size of 5.5 mm, which resulted in the appearance of metastases in the lungs of the animals. After tumor excision, mice were treated intraperitoneally with a single dose of BCNU (20 or 35 mg/kg) followed by a series of intraperitoneal THF-gamma 2 injections (1 microgram/0.5 ml/injection). Relative to untreated mice and those receiving chemotherapy alone, the antitumor action of the combined THF-gamma 2 chemoimmunotherapy protocol was significantly augmented according to the following in vivo parameters: (a) decreased postsurgical spontaneous metastatic burden; (b) prolonged survival time; (c) increased resistance to tumor cell challenge; and (d) massive infiltration of lymphocytes, polymorphonuclear cells, and macrophages in the lung tissue. The THF-gamma 2 immunotherapy also prevented a decrease in lymphocyte reactivity, otherwise induced by the tumor/BCNU chemotherapy. THF-gamma 2 immunotherapy resulted in restoration of the response to Lipopolysaccharide mitogenic stimulation and the allogeneic response. Our data suggest that postoperative THF-gamma 2 immunotherapy could be a valuable adjunct to anticancer chemotherapy as a treatment for metastatic arrest of melanoma tumor.

THF-γ2, a synthetic thymic hormone, increases effectiveness of combined chemotherapy and immunotherapy against RPC-5 murine plasmacytoma

The effect of a synthetic thymic hormone, THF-gamma 2, on the anti-tumor activity of spleen cells was studied in mice immunized against the RPC-5 tumor. Following two courses of the THF-gamma 2 treatment, the mean RPC-5 specific cytotoxic response of immune spleen cells was significantly increased when compared to normal cells (P less than 0.001) and to untreated immune spleen cells (P less than 0.04). In addition, THF-gamma 2 treatment improved the competence of immune spleen cells in adoptive immunotherapy (AIT) when performed in combination with chemotherapy by melphalan. Recipients of spleen cells from THF-gamma 2 treated mice showed a 35% increase in survival when compared to AIT with immune cells alone. The results suggest that THF-gamma 2 treatment of donors for AIT might be applicable to cancer therapy in humans.

Inhibition of mixed-lymphocyte reaction by quinine and lack of effect on plaque-forming cells and lymphoid-derived tumor cells.

Using Balb/c cells as responder cells and mitomycin-treated C57B1 cells as stimulator cells, it was found that quinine was inhibitory in a one-way mixed-lymphocyte reaction. Incorporation of [3H]-TdR was brought down to base levels in the presence of quinine. Quinine was not toxic for antibody-forming cells, and had no effect on plaque-forming cells formed by antibody-committed cells. The degree of [3H]-TdR incorporation of MOPC-315 tumor cells and Burkitts lymphoma cells was not affected by the presence of quinine in the medium. The cytotoxicity of quinine for mitogen-stimulated cells was demonstrated in soft-agar cultures.

Effect of melphalan administration on the activity of natural killer and natural cytotoxic spleen cells of normal and tumor-bearing mice

The effect of melphalan (L-PAM; L-phenylalanine mustard) administration on natural killer (NK) and natural cytotoxic (NC) activities of spleen cells from normal noninoculated BALB/c mice and mice bearing large MOPC-315 plasmacytoma tumors was investigated. Injection of L-PAM (7.5 or 15.0 mg/kg) had no effect on NK and NC activities of spleen cells from normal mice whereas stimulation by PHA was markedly suppressed. NK activity was markedly suppressed in spleens of tumor-bearing mice whereas NC activity was not affected. Therapy with L-PAM of tumor-bearing mice led to transient recovery of NK activity which was possibly related to the effect of L-PAM on macrophage suppressive activity on NK cells. It is concluded that NK and NC cell activities and the response to PHA stimulation are selectively affected by L-PAM administration.

Importance of the concomitant presence of palpable MOPC-315 tumor in stimulation of splenocytes by C-type MOPC-315 virus in Vitro

BALB/c mice inoculated with MOPC-315 tumor cells developed an antiviral response against C-type particles extracted from subcutaneous tumors of plasmacytoma-bearing mice as shown by in vitro stimulation of spleen cells from tumor-bearing mice by virus-containing preparations. Induction of blastogenic response by virus-containing preparations was found to occur in unfractionated spleen cell populations, the glass-wool non-adherent fraction (depleted of macrophages and tumor cells) and the nylon-wool non-adherent (T-enriched) fraction of spleen cells. The antiviral response was no more detectable in spleens of tumor-bearing mice cured by melphalan. Cured mice developed a strong antitumor immune response as shown by their resistance to challenge with a tumorigenic dose of MOPC-315 tumor cells. However, challenge with tumor cells of cured, resistant mice did not induce reappearance of antiviral response.