Cellular immunity to the mammary tumour virus in mice bearing primary mammary tumours

Tube Leukocyte Adherence-Inhibition Response to Related and Unrelated Tumor Antigens in Mammary Tumor-Bearing Mice

Tube leukocyte adherence-inhibition response to syngeneic mammary tumor antigens and alloantigens from Ehrlich ascites carcinoma and fibrosarcoma was studied in spontaneous mammary tumor-bearing C3H/Jax mice. The mice with limited tumor burden responded significantly to the mammary tumor antigen and the Ehrlich ascites carcinoma antigen. The reactivity disappeared with increased tumor load. Oscillatory responses in leukocyte adherence inhibition to the reactive antigens was observed with increasing tumor weight. There was no response to the alloantigen of fibrosarcoma.

Extraction of immunogenic murine mammary tumor antigens with 1-butanol

Solubilized tumor associated antigens (TAA) were prepared by a single phase 1-butanol extraction of a transplantable murine mammary adenocarcinoma (H2712), other syngeneic non-mammary tumors, normal mammary tissue, and embryonic tissues. The crude butanol extract (CBE) of H2712 was found to have tumor-specific activity both in vitro in the leukocyte adherence inhibition (LAI) assay and in vivo in an immunoprophylaxis assay. The failure to detect any of the major mammary tumor virus (MTV) envelope glycoproteins or internal core protein in CBE-H2712 and the failure of tumor-bearing mice to give a LAI response to CBE prepared from embryonic tissues suggests that the CBE antigens which are responsible for LAI activity are not viral or oncofetal antigens. Enzymatic treatment of the CBE-H2712 indicated that a sialated glycoprotein formed the antigenic determinants recognized in CBE by the LAI assay. Gel filtration of LAI-reactive CBE-H2712 on a Sephadex G-75 column isolated both the in vitro and in vivo tumor-specific activity in a fraction pool. Polyacrylamide gel electrophoresis revealed the presence of a 67 kD subunit as the major species in the active fraction.

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.

A radio (111In) capillary tube leukocyte adherence inhibition assay for the detection of specific tumor-associated immunity

The specific tumor-associated immune response of C3H/HeJ mice was determined at various times after subcutaneous injection with a transplantable mammary adenocarcinoma (H2712) using a radio (111In) leukocyte adherence inhibition (LAI) assay carried out in capillary tubes. Solubilized tumor-associated antigen prepared by a single phase 1-butanol extraction of the specific tumor and other transplantable tumors of different histological origin were used in the evaluation of LAI reactivity. The assay was found to be capable of detecting a significant antitumor response before the subcutaneous tumors became detectable by palpation. The response remained significant until the tumors were greater than 20 mm in diameter.

The early detection of host immune response to spontaneous mouse mammary tumors by leukocyte adherence inhibition

Longitudinal testing of C3H/HeJ female mice was carried out over a 52-week period with the leukocyte adherence inhibition (LAI) assay using solubilized tumor antigen prepared by 3 M KCl extraction. During this period, 75% of the mice developed histologically confirmed mammary adenocarcinomas. Of those mice 93% had a statistically significant (P less than 0.01) LAI response to soluble mammary tumor antigen prior to first detection of tumors by palpation. Five percent of the test group developed statistically significant LAI responses without development of detectable mammary tumors within a 34-week observation period. The first significant LAI reactivity of individual mice preceded the first detection of tumors by an average of more than 17 weeks.

Virus-specific cytotoxic activity to mammary tumor cells of sera from normal and tumor-bearing mice with inhibition at low dilutions

Sera from normal mice and mice bearing murine mammary tumor virus (MTV)-induced tumors showed cytotoxic reactions to the MTV-producing Mm5mt/c1 cell line. The reaction could be blocked by the addition of MTV, but not of purified gp52 and p28. In sera from tumor bearers, cytotoxic responses ranged from 15 to 66%; reactivity was generally highest when the serum was diluted 32 to 128 times. The cytotoxic sera from the normal animals showed a much lower activity; again, there was a lack of cytotoxic response at lower serum dilutions. Low dilutions (1 to 64) of sera from tumor-bearing and normal mice were found to inhibit the MTV-specific cytotoxic activity of rabbit anti-MTV serum on the Mm5mt/c1 cell line. Specificity of this phenomenon was deduced from the fact that there was less inhibition by the mouse sera of anti-Rauscher leukemia virus-specific cytotoxic activity to Rauscher leukemia virus-infected cells and of anti-vaccinia virus serum to vaccinia virus-infected cells. Absorption of the mouse sera with rabbit anti-gp52 serum almost completely abolished the inhibition; after absorption with MTV, inhibition was somewhat reduced. The effect of free gp52 and MTV/anti-MTV immune complexes on the anti-MTV immune response is discussed.

Factors interfering with cellular immunological responses to the murine mammary tumor virus in tumor-bearing mice

T-cell-enriched spleen cell fractions from BALB/c mice bearing virally induced mammary tumors become unresponsive with progressive tumor growth in the lymphocyte blastogenesis test, using purified mammary tumor virus (MTV) as an antigen. reactivity can be restored by mild trypsinization or extensive washing of the cells. When reactive cells from mice immunized with MTV were incubated with the wash fluid of the initially unresponsive cells. MTV-specific blastogenesis was inhibited. Washings of normal cells had no such effect. Leukocytes from tumor-bearing mice also become unresponsive to MTV in the leukocyte adherence inhibition (LAI) assay. Trypsinization or extensive washing does not restore reactivity. However, such treatment of reactive cells from immunized animals abolishes a positive reaction in the LAI assay, using MTV as an antigen. The washings of spleen cells from tumor-bearing mice inhibit the reactivity of leukocytes from immunized animals. Sera from these mice could block the reaction in both cellular immunological tests. The inhibiting factors appeared early after the onset of tumor growth. By means of the Sepharose bead immunofluorescence assay it was established that wash fluid and sera with blocking activity contain MTV antigens as well as anti-MTV antibodies.