Adaptation of influenza virus to growth in cultured murine methylcholanthrene induced tumors

Relationship of tumor-specific transplantation antigens to the histocompatibility complex: dissociation of in vitro alloantigen expression and in vivo alloimmunity from tumor-specific transplantation antigen strength

The studies reported here explore the relationship between tumor-specific transplantation antigens (TSTA) and (1) the expression of serologically defined specificities, and (2) the immunogenicity of H-2K- or H-2D-determined alloantigens on methylcholanthrene (MCA)-induced murine fibrosarcomas. Expression of H-2K and H-2D serologically-detected private specificities on groups of tumors raised in B10.A, B10.BR or B10.D2 strains varied greatly among tumors. No regular reciprocal or direct relationship to tumor TSTA strength was found. Each tumor, however, expressed H-2K or H-2D alloantigens stably as determined by direct cytotoxicity or absorption techniques. Even those tumors expressing little or no detectable alloantigen by serologic analysis were immunogenic in H-2K or H-2D incompatible congeneic hosts. This was assayed in terms of capacity to evoke primary or secondary tumor resistance, and to induce allo-antibody toward private H-2K or H-2D end specificities. An exception was that B10.BR tumors failed to induce anti-H-2Dk antibody despite strong surface alloantigen expression. While TSTA strength did not correlate with serologically detected alloantigen expression, TSTA strength did tend to correlate inversely with capacity to resist primary growth in the H-2K different host, and directly with resistance in the H-2D different host.

Augmented immunogenicity of tumor cell membranes produced by surface budding viruses: parameters of optimal immunization

Membranes prepared from tumor cells infected with surface budding viruses are much more immunogenic than membranes from uninfected tumor cells. Factors affecting immunization with membranes from virus-infected tumor cells were studied. Preparations made with influenza virus were clearly superior to those prepared with vesicular stomatitis virus (VSV). Membranes infected with VSV were maximally immunogenic at a dose equivalent to a 10% cell pack whereas influenza-virus-infected membranes were immunogenic at 1/100th of this dose. Subcutaneous inoculation was better than other routes of administration. Maximum protection against challenge with viable tumor cells was afforded by two inoculations of VSV-infected membranes spaced 3 days apart or a single inoculation with influenza-virus-infected membranes. Administration of membranes in complete Freund's adjuvant either had no effect of induced a slight degree of tumor enhancement. Immunization with influenza-virus-infected membranes significantly reduced tumor size and incidence even at a challenge dose of tumor cells which was 50 times the LD100.

Ability of delayed-type hypersensitivity reactions to distinguish tumor-associated antigens and histocompatibility antigens in soluble extracts from murine fibrosarcomas

The footpad swelling (FPS) test for delayed-type hypersensitivity in the mouse was evaluated for its ability to measure both tumor-associated antigens (TAA) and histocompatibility (H) antigens solubilized from methylcholanthrene (MCA) induced fibrosarcomas of C57B1/6 (B6) mice. Tests for TAA were performed in mice immune to syngeneic tumors while H-antigens were assayed in mice immunized with skin allografts. FPS was most intense in B6 mice challenged with TAA from the immunizing B6 tumor, but also occurred in response to cross-reactive TAA solubilized from another B6 fibrosarcoma. Tests for tumor-associated H-antigens in allograft immune mice were strongly positive in response to donor/recipient H-antigen differences and proved sensitive to shared third-party H-antigen differences. Comparison of soluble antigens from the same tumor maintained in vitro and in vivo revealed that, while both TAA and H-antigens could be detected in preparations from the in vivo tumor line, only TAA and not H-antigens could be detected by RPS in extracts prepared from the in vitro tumor line. These experiments have demonstrated that the mouse FPS test can distinguish both TAA and H-antigen specificities persent in the same complex mixture of tumor-cell antigens.

Immune enhancement of the tumorigenicity of hamster brain tumor cells persistently infected with measles virus

Studies were conducted on the tumorigenicity of a hamster brain tumor (HBT) cell line persistently infected with measles virus (MV). This cell population, termed HBT-M, exhibited decreased tumorigenicity in weanling hamsters when implanted intracutaneously. The lowered tumorigenicity of the HBT-M cells could be counteracted by concurrent hydrocortisone treatment restoring the tumor-producing capacity to levels comparable to those of the highly tumorigenic HBT cells. It was also determined that prior immunization of hamsters with MV resulted in enhancement of tumor formation from usually subtumorigenic doses of HBT-M cells. This increase in tumorigenicity appeared to correlate with high titers of MV antibody. Treatment of hamsters with cyclophosphamide resulted in a reduction of MV antibody titers and effected a decrease of HBT-M cell tumorigenicity to control levels. Preliminary studies with passive immunizations indicated that the enhancing factor could be transferred in the sera from hamsters hyperimmunized with MV. These data suggested that MV antibody may potentiate the development of neoplasia of cells persistently infected with MV in a manner similar to the enhancement of tumor growth by blocking antibody.

Protection of mice against cancer by immunization with membranes but not purified virions from virus infected cancer cells

The life span of C57/Bl mice inoculated with Lewis lung carcinoma cells was prolonged if the mice were pre-immunized with membranes from these cells infected in vitro with influenza virus. Likewise, BALB/c mice were protected against the malignant tumour WEHI-11 by prior immunization with extracts of cultured WEHI-11 cells which had been infected with influenza virus or Semiliki Forest virus (SFV). Partially purified SFV grown in WEHI-11 cells also protected mice from cancer grafts but neither highly purified SFV nor the glycoprotein from the envelope of this virus protected the mice. It is concluded that SFV-induced immunopotentiation against cancer is not due to covalent linkage of tumour specific transplantation antigen (TSTA) to viral envelope protein but more probably is due to the apposition of viral glycoprotein and cellular TSTA in the plasma membrane of the cancer cell.