Immunotherapeutic effects of tumor-specific transplantation antigens released by 1-butanol

Modulation of specific active immunization against murine melanoma using recombinant cytokines

Specific active immunization with tumour cells and IL-1beta or IL-2 was examined in a murine model. Mice were treated with irradiated B16 melanoma, IL-1beta or IL-2 only, or with B16 plus cytokines prior to i.v. challenge with viable B16. Lung metastases were recorded after 28 days. Treatment with cytokine alone was not protective. Treatment with B16 alone afforded moderate protection. Treatment with B16 in combination with either cytokine resulted in a significant level of B16 specific protection which was dependent on the dose of cytokine used. Multiple immunizations with B16 provided limited protection which was significantly improved with IL-2. Immunization with B16 in combination with both cytokines at doses that alone failed to enhance immunity resulted in significant protection, suggesting that the two cytokines act at least additively. These studies demonstrate the significant benefit of specific active immunization with tumour cells in combination with low doses of IL-1beta or IL2.

Active specific chemoimmunotherapy of lymph-node metastasis from a poorly immunogenic murine fibrosarcoma

The fibrosarcoma MCA-SP, which was recently induced with methylcholanthrene (MCA) in C3H/HeJ mice, displays poor immunogenicity in in vivo prophylaxis. A cell variant MCA-SPN1, which bears a tumor-specific transplantation antigen (TSTA) cross-reactive with the parental line MCA-SP, was selected because of its proclivity for axillary lymph-node metastases. Although these lymph-node metastases were resistant to sinecomitant (post-excisional) immunity, they were susceptible to combined active and passive specific chemoimmunotherapy, using tumor-specific, 1-butanol-extracted, preparative isoelectric focusing-purified, TSTA (1 microgram weekly sc injections), cyclophosphamide (CY, a single intraperitoneal 20 mg/kg dose), and adoptive transfer of immune splenic T lymphocytes, which had been re-stimulated in vitro with extracted TSTA and interleukin-2. This triple regimen both reduced the incidence of spontaneous lymph-node metastases, and prolonged the survival of tumor-bearing, as well as tumor-resected hosts. The results from local adoptive transfer assay using T-lymphocyte subpopulations of spleen and lymph nodes in these treated hosts suggested that Lyt 2+ cytotoxic T-lymphocytes (CTL) mediated in vivo tumor-neutralization. Thus TSTA/CY/CTL therapy activates tumoricidal host responses effective against the poorly immunogenic MCA-SP tumor and its lymph-node metastases.

Active specific immunotherapy with extracted tumor-specific transplantation antigen, cyclophosphamide, and adoptive transfer of tumor-specific cytotoxic T-cell clones

An L3T4-, Lyt2+ tumor-specific, cloned T-lymphocyte cell line (RTT-2) was isolated from a spleen cell population harvested from C3H/HeJ mice, following in vivo immunization against a syngeneic MCA-induced fibrosarcoma (MCA-F) and in vitro restimulation with 1-butanol-extracted, isoelectrophoretically purified MCA-F tumor-specific transplantation antigen (TSTA). RTT-2 required exposure to homotypic-extracted MCA-F TSTA in combination with low-dose IL-2 to maintain its specific cytotoxic activity in vitro. In vivo local adoptive transfer of RTT-2 caused specific neutralization of homotypic MCA-F, but not heterotypic MCA-D, tumor cells. Systemic in vivo transfer of RTT-2 alone augmented host resistance. In combination with a triple regimen of weekly doses of purified TSTA (1 microgram SC) and a single ip injection of CY (20 mg/kg), adoptive transfer of RTT-2 cells (1 X 10(7)) retarded the neoplastic outgrowth in and prolonged the survival of primary hosts bearing 3-, 7-, and 14-day established MCA-F tumors. In a spontaneous pulmonary metastasis model following amputation of a tumor-bearing limb, the triple regimen of TSTA/CY/RTT-2 markedly reduced the number of lung colonies. Thus RTT-2, which displays specific tumoricidal activity in vitro and in vivo, may afford a suitable tool to dissect T-cell receptors recognizing tumor markers on 1-butanol-extracted, MCA-F TSTA.

Specific chemoimmunotherapy in tumor-bearing mice with extracted antigen, cyclophosphamide, and intrasplenic administration of interleukin-2

The effect of daily intrasplenic (I-SP) injection of interleukin-2 (IL-2) in conjunction with specific chemoimmunotherapy with extracted tumor antigens and cyclophosphamide was assessed with the use of methylcholanthrene (MCA)-induced fibrosarcoma in C3H/HeJ mice. Injections of 80 U of human IL-2 were delivered transcutaneously into the spleen (I-SP), which had been relocated to the subcutis with its blood supply intact. Six daily I-SP injections into mice bearing MCA-F tumors activated immune spleen cells (SPC), as evidenced by specific neutralization of the MCA-F, but not the antigenically different MCA-D tumor, in local adoptive transfer assays. The immune cell phenotype was Thy 1.2+ Lyt 2+, based upon abrogation of tumor neutralization after depletion with monoclonal antibodies and complement. In a second series of experiments, primary hosts bearing established MCA-F tumors underwent therapy with 1 microgram 1-butanol extracted, isoelectrophoretically purified TSTA injected subcutaneously, a single intraperitoneal (IP) dose of 20 mg/kg cyclophosphamide (CY), and/or either IP or I-SP IL-2 injection. Triple chemoimmunotherapy with I-SP, but not IP, IL-2 retarded tumor outgrowth more effectively than single or double treatment protocols. Furthermore, in a third series of investigations, the triple therapy group showed both decreased numbers and incidence of spontaneous metastases from a subcutaneous implant of clone 9-4, a highly metastatic variant of MCA-F. Indeed, 35% of hosts that received triple therapy, but none of the animals treated with other regimens, were free of lung metastasis (P less than 0.02). Thus, tumor resistance engendered by chemoimmunotherapy with TSTA and CY is potentiated in vivo by I-SP administration of IL-2.

Antigen-specific therapy of experimental metastases

In a methylcholanthrene-induced tumor (MCA-F) model in C3H/HeJ mice, curative resection of a progressive tumor promotes artificial lung metastases following intravenous injection of a highly metastatic cell variant designated clone 9-4. The number of metastatic lung colonies depends upon the status of host immunity at the tumor resection: mice resected 7 or 14 days, but not 28 days after tumor inoculation display significantly retarded postoperative, experimentally induced lung metastases. The number of lung colonies in mice that had tumors resected at 14 days was three times greater than in mice that had 28-day neoplasms resected. Neither therapy with weekly injection of 50 micrograms tumor-specific transplantation antigen, which had been extracted using a single phase of 2.5% 1-butanol (CBE), nor 20 mg/kg cyclophosphamide (CY) alone prevented lung colonization. Assessment of helper-suppressor ratios in the spleen from mice after tumor surgery showed that CBE administration decreased the ratio in mice after resection of 14-day tumors, but not after resection of 28-day tumors. Combined therapy with specific tumor antigen and an antisuppressor cell agent reduced metastases, regardless of the tumor size.

Noncytolytic extraction of cell surface antigens using butanol

Incubation of viable tumor cells in single-phase aqueous solutions of 1-butanol releases a subset of peripherally-associated membrane proteins. Among the extracted components are tumor-specific and tumor-associated antigens of several human and experimental neoplasms. The extraction technique is noncytolytic: extracted cells remain viable and proliferate both in vitro and in vivo. Examination of the denuded cells has elucidated several important differences in cell-surface phenotype that have proved useful in studying the biology of such diverse systems as cellular communications and the mechanisms of hematogenous metastasis. It is anticipated that noncytolytic butanol extraction will continue to prove a powerful approach for the isolation and characterization of a variety of cell-surface antigens.

Carrier and adjuvant properties of liposome-borne tumor-specific antigens

The purpose of this study was to examine (1) the association of tumor extract proteins with phospholipid vesicles of varying physiochemical properties, and (2) the adjuvant and carrier properties of liposome-borne tumor antigens in the in vivo induction of an antitumor immune response. Cell surface antigens of the 3-methylcholanthrene-induced fibrosarcoma of C3H/HeJ mice, MCA-F, were extracted using 2.5% 1-butanol. Crude and electrofocused antigen preparations capable of eliciting a protective antitumor immune response were used to prepare liposome vaccines. The incorporation of extract proteins into liposomes formed by butanol dialysis (BVD) was three- to five-fold greater than the encapsulation of protein into the aqueous compartment of multilamellar vesicles (MLV). The electrochemical properties of the BDV had a significant effect on the induction of an antitumor response: Antigens borne on negatively charged, but not uncharged, liposomes were effective in protecting hosts against supralethal tumor challenge, and displayed a specific activity 20- to 50-fold greater than soluble antigen. Antigens carried by MLV were not effective in generating an immunoprotective response. The lipophilic characteristics of butanol-extracted antigens allowed (1) the passive adsorption of immunoprotective tumor antigen onto the surface of preformed vesicles, and (2) adsorption of MCA-F antigen onto the surface of an antigenically distinct tumor MCA-D. In the latter experiment, adsorption of MCA-F-specific antigen onto MCA-D cells resulted in a change in the membrane antigen phenotype as measured by indirect immunofluorescence. Although butanol released a lipophilic moiety from cells which spontaneously reassociated with phospholipid bilayers, no evidence for a lipoidal antigen was obtained when tumor-derived lipids were used as immunogens. This study demonstrates that butanol-extracted tumor antigen is lipophilic without being a lipid, and that negatively charged liposomes can be effective as carriers and adjuvants for tumor antigens in the induction of an antitumor immune response.

Selective extraction by 1-butanol of surface glycoprotein antigens from human melanoma cells

The butanol extraction method has previously been used to achieve selective release of tumor-specific transplantation antigens from mouse sarcoma cells. In this study we investigated the feasibility of this method for extracting four surface glycoprotein antigens (87K, 95-150K, HLA-DR, and HLA-A,B,C) from cultured human melanoma cells. Of the four antigens examined, only 95-150K and HLA-DR antigens could readily be detected in material extracted by 2%, 3%, or 5% butanol. The 3% butanol was found to be most effective in releasing these two antigens. Treatment of melanoma cells with less than or equal to 3% butanol did not decrease the viability of extracted cells as judged by either Trypan Blue dye exclusion or plating efficiency. Thus the noncytolytic butanol extraction method offers a promising approach to the isolation of certain glycoproteins such as 95-150K and HLA-DR from viable human melanoma cells for further purification and structural analysis.