Resistance of polyoma virus immunized mice to transplantation of established polyoma tumors

Immunotherapy for polyomaviruses: opportunities and challenges

Polyomaviruses are small DNA viruses present in mammals and birds, and in 1953 the first one to be described was murine polyomavirus. It was not until 1971 that the first two human polyomaviruses (HPyVs), BK virus and JC virus, were discovered and found to be common in humans, but only associated with disease in severely immunosuppressed patients. Since 2007, seven new HPyVs have been identified: KI polyomavirus, WU polyomavirus, Merkel cell polyomavirus, HPyV6, HPyV7, trichodyplasia spinulosa polyomavirus and HPyV9. Notably, Merkel cell polyomavirus was detected in Merkel cell cancer, a tumor mainly found in elderly and immunocompromised individuals, while trichodyplasia spinulosa polyomavirus was found in trichodyplasia spinulosa, a skin disorder observed only in immunosuppressed individuals. Consequently, many polyomaviruses cause problems in immunosuppressed individuals. This review deals with these issues, and the potential of the capsid protein VP1 to form virus-like particles for use as vaccines against polyomavirus infections.

In vivo acquired mechanisms of tumor cells local defense against the host innate immunity effectors: implication in specific antitumor immunity

As shown earlier, the cells transformed in vitro by several different oncogenes, or spontaneously, during in vivo growth in normal hosts would be gradually replaced by the highly-tumorigenic descendants co-expressing high H2O2-catabolizing and PGE2-releasing activities. Acquisition of (H2O2(CA) + PGE(S)) phenotype provides the cells with local defense mechanisms against the host innate immunity effectors. However, it remained unknown, whether the expression of (H2O2(CA) + PGE(S)) phenotype is implicated in susceptibility of tumor cells expressing tumor-specific transplantation antigens to rejection in immune animals. Here, with the use of SV40 in vitro transformed parental cells, negative in expression (H2O2(CA) + PGE(S)) phenotype, and their in vivo selected descendant tumor cell lines expressing this phenotype, we show that: (1) the rates of in vivo selection of the parental SV40 tumor cells expressing (H2O2(CA) + PGE(S)) phenotype are the same in normal and SV40-immune animals; (2) in vivo selected SV40 tumor cells expressing (H2O2(CA) + PGE(S)) phenotype, although they retain specific immunosensitivity, are 100 times less effectively rejected in SV40-immunized animals, as compared with their in vitro SV40-transformed parental cells. Thus, in vivo acquired immunologically non-specific local mechanisms of tumor cells defense against the host innate immunity effectors, significantly decreases the effectiveness of their specific immunorejection.

Requirement of the CD8+ or CD4+ T lymphocyte subsets for the rejection of lymphoma and fibrosarcoma grafts studied in gene knockout hosts

Rejections of the retrovirus induced lymphomas (ALC and RBL-5) and the methylcholanthrene (MCA) induced fibrosarcoma (MC57X) grafts were tested in syngeneic CD8 and CD4 single and double knockout C57BL/6 mice. The results with the lymphomas showed that the CD8+ T cell deficiency prevented the development of rejection response induced by immunization. Deficiency of the CD4+ T subset abrogated also the rejection of ALC. Immunity against the fibrosarcoma cells developed in both type of single knockout mice, but not in the ones which lacked both CD4+ and CD8+ T cells. Thus CD8+ T cells were required for rejection of the lymphoma cells, while the CD4+ T cells only mediated a weak response. In absence of CD8+ T cells, CD4+ T cells were sufficient to reject the fibrosarcoma cells.

p53 as a target for anti-cancer immunotherapy

The key to specific and non-toxic cancer therapy is likely to be identification and targeting of processes that are absolutely unique to the tumor. One such approach is to target cells expressing mutations in the oncoproteins that led to the development of the cancer, such as p53. In animal model systems, highly mutant p53-specific cytotoxic T cells can be induced, but it remains to be seen whether this can be translated into clinical practice, and what proportion of tumors will respond. In this review, the potential and problems of immunological targeting of mutant p53 in solid tumors are discussed.

An intracisternal A-particle sequence codes for an antigen recognized by syngeneic cytolytic T lymphocytes on a mouse spontaneous leukemia

Cytolytic T lymphocyte (CTL) clones directed against spontaneous mouse leukemia LEC have been obtained. By transfecting a cosmid library into cells which were then tested for their ability to stimulate the CTL, we identified the gene coding for the antigen recognized by one of these CTL clones. It is the gag gene of an endogenous defective retrovirus that belongs to the intracisternal A particle (IAP) family. A gag-encoded nonapeptide presented by the H-2 Dk molecule caused recognition by the anti-LEC CTL clone. Southern blot and polymerase chain reaction analyses indicated that the expression of the antigen by the LEC tumor cell line resulted from the transposition of an IAP sequence into a new genomic location.

The tumor rejection antigen separated from Rous sarcoma virus-induced murine fibrosarcoma exhibits a molecular weight of approximately 60 kD but differs from functional pp60src

The tumor antigen capable of inducing tumor resistance (tumor rejection antigen; TRA) was obtained in a solubilized form by sodium dodecyl sulfate (SDS) extraction of plasma membrane fraction from Rous sarcoma virus (RSV)-induced CSA1M fibrosarcoma cells (BALB/c origin). Analyses by Sephacryl S-300 gel filtration and SDS-polyacrylamide gel electrophoresis revealed that TRA activity was recovered in the fraction with a molecular weight of approximately 60 kD. Unfractionated crude SDS-solubilized preparation contained gp70 as detected by rabbit anti-gp70 antiserum, whereas such reactivity was lost in the fraction exhibiting the molecular weight of about 60 kD. Since this fraction retained pp60src activity, the relation of TRA to pp60src was further investigated. pp60v-src was also obtained from the lysate of v-src-expressing yeast transformant. Immunization of BALB/c mice with such pp60v-src-containing lysate failed to induce any significant tumor protection. The above 60 kD fraction of CSA1M solubilized antigens was allowed to bind to Sepharose beads coupled with anti-pp60src monoclonal antibody and separated into the bead-bound and bead-unbound fractions. The bead-bound fraction that was recovered from pp60src-binding beads (pp60src-positive fraction) did not exhibit the TRA activity. In contrast, immunization with the fraction depleted of pp60src activity (bead-unbound fraction) resulted in potent tumor protection. These results indicate that the solubilized membranous component(s) of CSA1M with a molecular weight of approximately 60 kD, which is distinct from functional pp60src, functions as the TRA against RSV-induced CSA1M tumor cells.

Separation of the tumor rejection antigen of Rous sarcoma virus-induced murine fibrosarcoma

The tumor antigen capable of inducing tumor resistance (tumor rejection antigen; TRA) was separated and some of its physicochemical properties were characterized. Cytosol and plasma membrane fractions were separated from Rous sarcoma virus (RSV)-induced CSA1M tumor cells. Immunization with membrane but not cytosol fraction of these tumor cells together with complete Freund's adjuvant resulted in complete protection against subsequent challenge with viable CSA1M cells. The TRA activity contained in the membrane fraction was recovered in the sodium dodecyl sulfate (SDS)-solubilized fraction after the SDS-extraction of CSA1M membranes. This CSA1M SDS-solubilized preparation gave protection against syngeneic RSV-induced CSA9F tumor cells as well as the homologous tumor cell type, but failed to induce resistance to RSV-unrelated tumor cells. The membrane or SDS-solubilized fraction from RSV-unrelated tumor cells was unable to generate anti-CSA1M protective immunity. Physicochemical analyses have demonstrated that TRA activity in the SDS-solubilized fraction was completely abolished by treatment with proteinase K but was only marginally affected after treatment with glycosidase mixture. When the SDS-solubilized preparation was applied to a Sephacryl S-300 superfine column, TRA activity was recovered in the range of molecular weight of 50-90 kD. Further fractionation of this TRA-positive fraction by SDS-polyacrylamide gel electrophoresis revealed that the molecular size of TRA is 56-68 kD. These results indicate that membrane proteins which were isolated from CSA1M tumor cells and have a molecular size of about 60 kD are capable of inducing RSV-induced tumor-specific in vivo protective immunity.

Immunization against the polyoma virus-induced tumor-specific transplantation antigen by early region mutants of the virus

To investigate the relation between the polyoma tumor-specific transplantation antigen and the virus-coded proteins, mice were immunized by inoculation of a variety of viable polyoma virus mutants and then challenged with polyoma virus-induced tumors. Two classes of early region mutants were used. One class produces a normal small T-antigen and truncated middle and large T-antigens. The second class (hr-t mutants) forms a normal large T-antigen together with N-terminal fragments of small and middle T-antigens. All mutants, transforming as well as nontransforming, induced protection against polyoma virus tumors. However, there were quantitive differences between the mutants. The finding that an hr-t mutant could induce tumor rejection suggests that full-length middle and small T-antigens are not necessary for the induction of this response. Since intact middle T-antigen is the only virus-coded protein known to associate with the plasma membrane, the possibility must be considered that the polyoma virus tumor-specific transplantation antigen consists of cellular components.

Mechanisms of cellular cytotoxicity mediated by effector cells from rats with spontaneous tumors

We have previously shown that effector cells from BD X rats bearing spontaneous tumors display increased cytotoxicity towards syngeneic tumor cells compared to effector cells from untreated rats (Zöller and Matzku, 1980 a). The increased in vitro cytotoxicity of lymphoid cells from tumor-bearing (TB) animals was not T-cell mediated and the question was raised, whether it was due solely to increased natural killer (NK) cell activity, or whether humoral factors could also be involved. We now prove that in a long-term assay, the presence of B cells is indeed mainly responsible for increased TB cytotoxicity, since: (1) After depletion of surface immunoglobulin positive cells (s-Ig+), TB cytotoxicity no longer exceeds cytotoxicity of effector cells from untreated rats; (2) Mixtures of s-Ig+ cells from TB animals with Fc-receptor positive (Fc-R+) cells from untreated rats restore the increased TB cytotoxicity; (3) Addition of rabbit Fab' anti rat F(ab')2 reduces TB-effector cell cytoxicity. A minor contribution of the increased TB cytotoxicity by activation/numerical increase of NK cells will be discussed.

Uninhibited growth and metastases of herpes simplex virus-transformed cells in virus-sensitized hosts

Four established tumour lines of hamster cells transformed by herpes simplex virus (HSV) but not shedding the virus were examined for continued expression of virus-associated antigens. Hamster or rabbits, appropriately immunized to the tumour cells, produced virus-neutralizing antibody. The serum titres were invariably low, suggesting that only small quantities of virion antigen were present in the cells. Hamster sensitized to HSV and resistant to virulent virus challenge did not reject low numbers of tumour cells, nor was the incidence of lung metastases significantly reduced. Virus-sensitized lymph-node cells, readily cytotoxic for HSV-infected hamster embryo fibroblasts, did not lyse any of three transformed lines tested in an 18-h 51chromium release test. Animals that had their tumour excised demonstrated no or only modest resistance to tumour rechallenge. Thus, virus-specific transplantation rejection antigen could not be detected in the HSV tumour lines although low levels of virus structural antigens were present.

Certain aspects of analysis of complement dependent antibody in breast cancer patients

Specific anti-breast cancer complement dependent antibody (CDA) was sequentially determined in the sera of patients before and after mastectomy or during progressive recurrent breast cancer. Several observations were made. (1) There appears to be a different pattern of antigenic cross-reactivity detected by cancer patients' anti-tumor CDA than by their anti-tumor cell-mediated immunity; the former being broader than the latter. (2) Patients can be classified into three categories: those with persistent anti-tumor CDA pre- and post-mastectomy; those with detectable CDA post-mastectomy but not pre-mastectomy; and those with only occasionally detectable CDA. (3) Some sera obtained from patients with clinically evident tumor inhibited anti-tumor CDA found in the sera of other cancer patients. The significance of these results are discussed.

In vivo and in vitro TSTA-inducing activity of temperature-sensitive (ts) mutants of SV40

In vivo TSTA induction in Syrian hamsters was studied with the use of SV40 ts mutants (A, B, C, BC and D). The ts A30, TS A239 and possibly also the ts BC210 mutants were defective in resistance-inducing activity in hamsters in contrast to wild type SV40 and other ts mutnats. At the permissive temperature ts A30 and ts A239 did not induce TSTA in hamster cells during abortive infection in vitro, while they did so in green monkey cells at both permissive and non-permissive temperatures. In hamster cells transformed by ts A30, ts A239 and ts A209 mutants none at all or very little TSTA was detected by in vivo transplantation immunological tests. Thus, expression of TSTA induced by these three SV40 ts A mutants was found to be dependent from the species of infected cells and was being a temperature independent viral function.

Cell-mediated tumour immunity in patients with transitional cell carcinoma of the urinary bladder

Some recent data on problems of cell-mediated immune reaction directed against tumour-associated antigens (TAA) of transitional cell carcinomas of the urinary bladder (BTCC) are reviewed. All of the 13 samples of BTCC examined in our laboratory using a lymphocytotoxicity microassay contained the characteristic TAA of urinary bladder carcinomas. TAA were absent in 14 control tissue samples. Forty-seven out of 70 (67%) patients with BTCC developed cytotoxic lymphocytes reacting with BTCC cells. However, cytotoxic lymphocytes were also found in the blood of 8 out of 165 (4.8%) control lymphocyte donors.

Phenolization of bladder in treatment of massive intractable hematuria

Intractable hemorrhagic cystitis secondary to radiation or cyclophosphamide (Cytoxan) therapy could lead to serious complications; however, intravesical instillation of phenol has reduced the dilemma of this life-threatening problem. We present a case of intractable hemorrhagic cystitis secondary to cyclophosphamide therapy treated with 100 per cent phenol with no untoward side effects. Since formalin instillation into the bladder has been associated with severe complications, phenol appears to be safer and more effective in the treatment of intractable hematuria, and, therefore, its clinical trial is recommended.