Gerald L. Bartlett

The Shope papilloma-carcinoma complex of rabbits: a model system of neoplastic progression and spontaneous regression.

Publisher Summary The majority of domestic rabbits developed invasive, metastatic, and, ultimately, lethal epidermoid carcinomas. The Shope papilloma has a restricted geographic range, mostly confined to the high plains of the western United States. SPV (Shope papilloma virus) produced papillomas with equal facility on the skins of laboratory-infected jackrabbits, snowshoe hares , domestic rabbits, and cottontails. Papillomas cannot be induced in fetal, neonatal, suckling, or adult rat skin by direct inoculation of SPV suspensions or infectious DNA. Susceptibility to SPV infection is also determined by factors related to cell phenotype. Rabbit epidermal cell transformation by SPV requires interaction with mesenchyme. Vitamin A deficiency or excess can produce striking alterations in the differentiation of epithelia of various types. SPV replication in cottontail papillomas is also modulated by phenotypic factors—namely, epidermal maturation and keratinization. Independent studies have confirmed the presence of arginase in Shope papilloma but have not supported the assertion that the enzyme is encoded by the SPV genome. The Shope papilloma-carcinoma complex is an excellent model of neoplastic progression. Papillomas that become malignant undergo a characteristic series of gross morphological changes.

Relationship of tumor leucocytic infiltration to host defense mechanisms and prognosis.

SummaryThe interface between the tumor and the host is often the site of leucocytic infiltration. We will examine the dea that the infiltrating leucocytes of human and experimental tumors are components of the host ammunological defense against the tumor, and that the presence of the infiltrate is a marker of favorable prognosis. Leucocytes could infiltrate tumors because of an active immune response, either nonspecific or specifically directed to tumor-associated antigens. Leucocyte influx may also occur because of chemotactic factors secreted by the tumor cells. Some tumors release factors which enhance vascular permeability and permit improved access by leucocytes to the tumor focus. The consequences of leucocytic infiltration include tumor cell cytolysis, cytostasis, or stimulation of proliferation. The present state of our knowledge of the interactions between tumor cells and infiltrating leucocytes precludes broad generalization of mechanisms. Further study will probably reveal that the mechanisms are diverse, and that there are some systems in which immune interactions occur at this interface and others in which they do not.

Shope rabbit papillorna-carcinoma complex a model system of HPV infections

Abstract To the busy, practicing dermatologist, an animal model system may appear to offer little benefit to patient diagnosis or management; however, animal model systems often can provide answers to vexing clinical problems that cannot be approached in patient studies because of ethical restrictions or logistic problems. Animal models are imperfect substitutes for human diseases; but because they share similar mechanisms, an animal model can provide an opportunity to test hypotheses that contribute to an understanding of the human counterparts. The Shope rabbit papilloma is remarkably similar in etiology and mechanism to many naturally occurring lesions induced by human papillomaviruses. In that sense, the Shope system can contribute to an understanding of human wart-virus infections. In a broader context, the Shope papilloma-carcinoma complex can provide an understanding of the determinants of neoplastic progression and of host interactions with neoplastic tissue. The purpose of this report will be to review some of the more important aspects of this experimental tumor system, especially those that are relevant to clinical situations. This review will be limited in scope. For more detailed coverage, the reader is referred to another article which we published elsewhere. 1

Augmentation of immunity to line 10 hepatoma by BCG. Comparison of different BCG preparations

The line 10 hepatoma of strain 2 guinea pigs was used in order to evaluate the adjuvant efficacy of eight Bacillus Calmette‐Guérin (BCG) suspensions which differed in strain, method of preservation, or dosage. Lyophilized Tice BCG was consistently the most effective preparation. Each strain had adjuvant activity in at least one experiment. The method of preservation of BCG (fresh‐frozen vs. lyophilized) did not have a consistent, predictable influence on adjuvanticity. A ten‐fold increase in the dosage of BCG or of the whole vaccine was not supraoptimal. Cancer 46:488–496, 1980.

Immunogenicity of “viable” tumor cells after storage in liquid nitrogen

SummaryInjection of vaccines containing BCG and irradiated L10 hepatoma cells into strain 2 guinea pigs led to arrest and regression of viable L10 cells injected contralateral to and simultaneous with the vaccine. If the tumor cells in the vaccine had been stored in LN2, the vaccine was significantly less effective. The diminished immunogenicity of the stored cells could not be attributed to the sequence of freezing and irradiation, nor to the presence of dead cells which had been killed during cryopreservation. We concluded that cells which had been stored in LN2 had undergone changes which decreased their immunogenicity but which did not alter permeability to trypan blue.

Immunotherapeutic effectiveness of BCG inactivated by various modalities

Factors responsible for the limited effectiveness of Bacillus Calmette‐Guérin (BCG) immunotherapy are not completely understood. One limitation is that although the effect is dose‐related, high‐dose administration increases the risk of BCG toxicity, possibly the result of disseminated BCG infection. In the present study, we compared the relative effectiveness of Tice lyophilized BCG which was inactivated by heat, sonication, irradiation, streptomycin, or isoniazid (INH). The model systems were the 13762A rat mammary adenocarcinoma and the line 10 guinea pig hepatoma. In the 13762A system, tumors were injected on day 7 with living or killed BCG preparations, or with Corynebacterium parvum as a positive control. Tumors were excised on day 20. Rats treated with surgery alone usually died within 40–50 days with extensive metastases to lymph nodes, lungs, and viscera. Guinea pig line 10 hepatoma was treated with vaccine containing irradiated tumor cells and BCG. In both the rat and guinea pig models, BCG inactivated by means of irradiation was as effective as viable BCG and heat‐killed BCG also had a strong effect. Streptomycin treatment diminished the efficacy of the BCG and sonication destroyed BCG effectiveness even though the organisms were not all killed. The INH treatment of tumor‐bearing rats did not alter the benefits of single or repeated injections of high‐dose viable BCG, irradiated BCG, or C parvum. We conclude that inactivation of BCG with heat, irradiation, or INH host treatment preserves but does not improve the immunotherapeutic benefits of BCG. Cancer 46:480–487, 1980.

Characteristics of T cells involved in the expression of delayed hypersensitivity and tumor rejection immunity to 13762A rat mammary adenocarcinoma

The 13762A rat mammary adenocarcinoma is poorly immunogenic and metastasizes with high frequency to regional lymph nodes and lungs. Tumor rejection immunity (TRI) may be readily transferred with oil-induced peritoneal exudate cells (PEC) from immune rats but the transfer of delayed hypersensitivity (DH) was less reliable. The purposes of the present study were: (1) to compare the optimum conditions for transfer of DH and TRI; (2) to determine whether the TRI effectors were derived from cells which recently divided in the donor; (3) to determine the relative sensitivity of DH and TRI effectors to treatment with radiation and mitomycin C; and (4) to identify the phenotypes of the T-cell subsets responsible for transfer of DH and TRI. The results indicate that transfer of DH requires more cells or a longer interval between transfer and challenge than did TRI. Treatment of the donor with vinblastine (VBL) or hydroxyurea (HU) continuously for 5 days prior to harvest of PEC impairs effectiveness of transferred DH and TRI. This indicates that the effectors proliferated during the period before harvest of the PEC. Treatment of the PEC in vitro with mitomycin C or gamma-radiation eliminates transfer of DH and TRI, but DH is more radiosensitive than TRI. T-cell subsets were identified with the monoclonal antibodies W3/13 (pan-T), W3/25 (helpers), and OX8 (cytotoxic/suppressors). The TRI effectors are nonadherent and express W3/13, W3/25, or OX8 antigens. The, DH effectors are also nonadherent but expressed only W3/13 or W3/25 antigens. Thus, DH systemic adoptive transfer requires more cells or a shorter interval between transfer and challenge than TRI. Both DH and TRI effectors replicate in the donors prior to transfer. The DH effectors are helper T cells but TRI effectors include cells with helper or cytotoxic T-cell marker antigens. We conclude that TRI and DH are probably functions of two T-cell subsets which differed in radiation sensitivity and membrane phenotype. CY pretreatment of the recipients of immune PEC potentiate TRI. The potentiated effects are reduced if the recipients are given nonadherent spleen cells. The responsible cells expressed W3/13 and W3/25 antigens. Thus, CY potentiation is attributed to the depletion of precursors of suppressor T cells.

Distinct T-cell proliferative responses to 13762A rat mammary adenocarcinoma and derived clones

We examined the in vitro responses of immune lymphocytes to the tumor antigens of the syngeneic rat mammary adenocarcinoma 13762A. This tumor readily metastasizes to lymph node and lungs and is poorly immunogenic. Rats were immunized with a highly immunogenic clone (18A) which was isolated as a spontaneous variant from the parental 13762A tumor. Clone 18A grew progressively in irradiated rats but regressed completely in normal rats. Animals immune to 18A tumor were also immune to parental 13762A. Lymphocytes obtained from the spleen and peritoneum of immune rats were tested for specific proliferation to parental 13762A tumor and clone 18A to determine whether similar cross-reactivity to these tumors occurred in vitro. We found an anatomical difference in localization of immune lymphocytes which reacted to the two tumor cell lines. Immune peritoneal exudate cells (PEC) responded strongly to clone 18A but poorly to 13762A, while immune spleen cells from the same animals responded predominantly to 13762A tumor. After 7 days culture, PEC proliferating in response to clone 18A contained 84-95% W3/25+ T-helper cells, and only 5-8% OX8+ cytotoxic/suppressor cells, while analogous cultures of spleen cells responding to parental 13762A tumor consisted of 60-80% W3/25+ cells and 20-23% OX8+ cells. Immune spleen cell cultures stimulated with 13762A tumor generated cytotoxic lymphocytes which specifically lysed both parental 13762A and clone 18A cells. We conclude that despite cross-reactivity in vivo and in vitro, antigens present on 13762A and 18A tumor cells stimulated different subsets of immune T cells.

Immunotherapy of postoperative metastases of 13762A rat mammary adenocarcinoma. Comparative effectiveness of BCG substrains and methods of preparation

Six Bacillus Calmette‐Guérin (BCG) substrains (Phipps, Pasteur, Connaught, Glaxo, RIV, and Tice) and two methods of preparation and storage (pellicle‐lyophilized, dispersed‐frozen and dispersed lyophilized) were directly compared in a standard immunotherapy protocol. Complete Freunds adjuvant and Bordetella pertussis vaccine were also studied. All experiments included direct comparisons with Corynebacterium parvum. The immunotherapy assay system was the 13762A rat mammary carcinoma in which immunity stimulants were given intratumorally on day 7, followed by excision of primary tumors on day 20. In this protocol, C parvum produced strong inhibition of established metastases and some cures. All of the BCG strains except Glaxo were effective in at least one experiment but none was as strong or as consistent in its effects as C parvum. No strain of BCG or method of preparation was clearly superior to the others. The B pertussis vaccine and complete Freunds adjuvant were ineffective. Cancer 46:500–507, 1980.

Treatment of cancer using Corynebacterium parvum: similarity of two preparations in four animal tumor models.

The tumor inhibitory properties of Corynebacterium parvum obtained from Burroughs Wellcome (CP‐BW) or from Institut Merieux (CP‐IM) were compared in four animal tumor models: the CaD2 mouse mammary carcinoma treated by intravenous (I.V.) or intratumoral (I.T.) injection of C. parvum; 13762A rat mammary adenocarcinoma treated by I.T. injection of C. parvum either alone or combined with excision of the primary tumor; LSTRA murine leukemia and line 10 cavian hepatoma, each treated with vaccines containing irradiated tumor cells and C. parvum. Both preparations were active against each tumor. In most comparisons the potency of the two materials was not different, but in a few cases the CP‐BW was effective at a lower dose than was the CP‐IM. These results demonstrate the versatility of C. parvum for use in a variety of immunotherapy procedures and show that the potencies of the two major types of C. parvum are very similar.