Humoral factors abrogating cell-mediated immunity in the tumor-bearing host

Anti-tumor immunity and mechanism of immunosuppression mediated by tumor cells: role of tumor-derived soluble factors and cytokines

The immune system plays a crucial role in the protection against tumor growth and progression. However, the activation of the immune system against the neoplastic cells does not always occur and, therefore, tumor cells are able to grow and progress continually in the host. It has now been realized that tumor cells themselves produce many of the important factors that are responsible for dismounting of effective immune response. These tumor-derived soluble factors invariably subdue the functions of almost every immune cell population. Therefore, we attempted to underline the mechanism of anti-tumor immune response and immunosuppression induced by tumor cells.

Auto-anti-idiotypic antibodies in mice hyperimmunized with a chemically induced bladder carcinoma

Purified immunoglobulin from the serum of mice hyperimmunized with syngeneic tumour cells was compared with a monoclonal anti-idiotope antibody, obtained by immunizing mice with antibody to the same tumour. Both the immunoglobulin and the monoclonal antibody were specifically immunogenic in syngeneic (BALB/c) mice as tested by in vitro and in vivo assays of cell-mediated immunity. In both cases the reactivity was absent in immunoglobulin heavy chain gene complex-1-(Igh) allotype congenic (CB.20) mice, indicating Igh-restriction of immunogenicity. The active material in hyperimmune serum thus has the properties of auto-anti-idiotypic antibody, complementary to T cell idiotopes.

Regulation of tumor growth by soluble spleen factors: effect of tumor resection

Supernatants of cultured spleen cells (SCS) from small-tumor-bearing mice (STBM) and large-tumor-bearing mice (LTBM) were tested in vivo by their ability to modify tumor development. We found that when inoculated with S13 tumor cells into the foot-pad of syngeneic normal BALB/c mice, SCS enhanced tumor growth as well as accelerated tumor takes. When STBM and LTBM were operated on, the persistence of the enhancing activity by SCS was found to be associated with tumor size at the time of tumor removal. As early as 24 hours after small-tumor resection, enhancing activity disappeared or diminished to undetectable levels. On the other hand, enhancing activity by SCS from large-tumor-resected mice (LTRM) persisted until 15 days after surgery, and then faded. Enhancing activity associated with SCS from S13-tumor-bearing mice (TBM) was also seen when injected with M3 cells, a syngeneic unrelated tumor. Normal SCS did not affect tumor development. It seems that the rate of disappearance of enhancing activity observed in SCS from S13-tumor-resected mice (TRM) is mainly dependent on the size of tumor burden at the time of surgery.

Mutational analysis of the human immunodeficiency virus: the orf-B region down-regulates virus replication

Mutations were made by recombinant DNA techniques in an infectious molecular clone of the human immunodeficiency virus San Francisco isolate 2 (HIVSF2) [formerly the prototype isolate of the acquired immunodeficiency syndrome-associated retrovirus (ARV-2)]. The effect of these changes on the replicative and cytopathologic properties of the virus was studied by transfecting modified virus clones into cultured human cells. Mutations in the gag, pol, env, and tat regions precluded virus replication and cytopathology in lymphoid cells. A mutation in orf-A dramatically reduced but did not abolish virus replication. Mutant viruses with deletions in the orf-B region were highly cytopathic and replicated to approximately 5-fold higher levels than wild-type virus. They also produced approximately 5-fold more viral DNA in infected lymphoid cells than did wild-type virus. Thus, the orf-B region may function to down-regulate virus replication. This mutational analysis of the HIVSF2 genome is a means of assessing genes regulating viral replication and cytopathology.

Immune complex-like material in the serum and plasma exchange in patients with metastatic cancer

Clinical significance of immune complex-like material in the serum was investigated in tumour patients undergoing plasma exchange with albumin-saline solution and subsequent chemotherapy. Immune complexes were detected by the Clq binding assay or the Raji cell radioimmunoassay in nine out of forty-five patients before this therapy. Levels of immune complexes were decreased to 10-30% of the initial value by plasma exchange depending on exchanged plasma volume. In contrast to other serum proteins like alpha 1-antitrypsin and alpha 2-macroglobulin, which showed protein specific increase during follow up after plasma exchange in all patients, recovery rates of immune complexes and IgG were highly individual but parallel in each patient. Clinical response to this protocol did not correlate with immune complex status, suggesting that removal of the measured immune complex like material had little clinical significance or was not longlasting enough to provide therapeutic benefit.

In vitro monocyte maturation in squamous-cell carcinoma of the lung: influence of humoral factors

A previously described defect of in vitro monocyte maturation in patients with squamous-cell carcinoma of the lung (SCC) has been investigated further. The maturation of patients' monocytes in pooled normal human serum was significantly better than in autologous serum. Conversely, the maturation of normal control monocytes was significantly depressed in patients' serum. The defect has been shown to be due to the presence of an inhibitory factor, rather than the lack of a necessary component in the patients' serum. Artificially aggregated gamma-globulin inhibited monocyte maturation in vitro, but the presence of immune complexes in the serum of many patients with SCC did not correlate well with the depression of in vitro maturation of monocytes from the same patient. Similarly, pregnancy-associated alpha 2-glycoprotein, in increased amounts in the serum of patients with SCC, showed no correlation with monocyte maturation. The addition of soluble extracts of tumour, but not of surrounding normal lung tissue significantly inhibited monocyte maturation. The results suggest that the defective monocyte maturation in patients with SCC is at least in part due to serum inhibitory factors, which are likely to be a heterogeneous group.

Lymphocyte-mediated lysis of tumor cells in vitro (ADCC), induced by serum antibodies from patients with urinary bladder carcinoma or from controls

IgG fractions from serum of patients with transitional-cell carcinoma of the urinary bladder (TCC), patients with carcinoma of the prostate (CC) and healthy donors (HD) were tested for their capacity to induce antibody-dependent lymphocyte-mediated cytotoxicity (ADCC) to tumor cells in vitro. Lymphocytes from healthy donors were selected for low natural cytotoxicity to the target cells from established cell lines of TCC or other origins. IgG was prepared by adsorption of serum to Sepharose-bound protein A from Staphylococcus aureus and subsequent acid elution. When tested against a panel of six different target cells, most individual IgG preparations from all three donor groups contained antibodies inducing ADCC to some of the target cells. When IgG preparations from II untreated TCC patients were studied for ADCC induction to the TCC target T24 and the colon carcinoma HT29, cytotoxicity to T24 was, on an average, significantly higher than that to HT29. For IgG preparations from 18 TCC patients, treated with radiotherapy, a similar difference was seen but was not statistically significant. IgG preparations from II patients with carcinoma of the prostate and from 12 healthy donors did not show this differences. Moreover, while individual IgG preparations from untreated TCC patients were, on the average, significantly more cytotoxic to T24 than those from either of the two control groups, no such differences were seen when HT29 was the target. On the contrary, IgG preparations from patients with prostatic carcinoma were significantly more cytotoxic to HT29 than those from healthy donors. The results suggest that TCC patients develop a disease-related humoral immune response, superimposed on a "natural" immunity to a variety of antigens on the target cells used. The nature of the antigens involved in these reactions remains to be established. However, the results are compatible with previous findings, in these patients, of a bladder-tumor-related cellular cytotoxicity, to a large extent caused by the patients' own antibodies.

Multimodal immunotherapy of primary gastrointestinal tumors in rats. 1. Histologic correlation

The effect of multimodal immunotherapy was studied in rats bearing primary gastrointestinal tumors induced by 1,2-dimethylhydrazine dihydrochloride. Multimodal immune manipulation consisted of combinations of splenectomy, C. parvum, unblocking serum, unblocked lymphoid cells, and levamisole. Such immunologic intervention resulted in significant inhibition of tumor growth, and their metastasis. Ten of 10 untreated rats, 8 of 8 rats treated with splenectomy alone and 10 of 10 rats treated with normal rabbit serum died of progressive tumor growth. None of the rats treated with combinations of splenectomy, unblocking serum, unblocked lymphoid cells, C. parvum and levamisole succumbed to progressive tumor growth during the observation period. The histologic evidence of tumor destruction was obtained in 18 of 22 tumors in rats of groups receiving multimodal immunotherapy.

An immunoregulatory factor associated with spleen cells from tumor-bearing animals. I. Effect on tumor growth and antibody production

An immunopotentiating factor associated with spleen cells of C57BL/6J mice bearing the 3LL tumor is described. Supernatants of cultured spleen cells from tumor-bearing mice (TBM) augmented the generation of both 19S and 7S antibody-producing cells, when injected with sheep erythrocytes into syngeneic C57BL/6J mice. The enhancing supernatant acted both as a polyclonal activator, when injected in the absence of antigen, and as a potentiator of specific antigen-dependent humoral immune responses, when injected in the presence of antigen. It was found to augment induction of specific memory, but not memory expression. Concomitantly with their influence on humoral immune responses, TBM spleen cell supernatants enhanced tumor growth when injected, mixed with 3LL tumor cells, into syngeneic recipients. The secretion of a factor which augments antibody production was not confined to the 3LL tumor system. Spleen supernatants of C47BL mice carrying the B16 melanoma and those of C3H mice carrying the KHT sarcoma had a similar effect on antibody production. These findings suggest that an immunoregulatory factor(s) appears in spleen cells of TBM as a result of their interaction with the neoplastic tissue. This factor can potentiate production of antibodies, possibly also against tumor-associated antigens. The relevance of the immunopotentiating effects of such factor(s) to tumor growth is discussed.

Blocking factors against melanoma leucocyte-dependent antibody: relationship to disease activity in melanoma patients

Previous studies have shown that many melanoma patients have cytotoxic leucocyte-dependent antibody (LDA) which is inhibited by factors in their sera. These factors were shown to be small molecular weight glycoproteins which could also be identified in the supernatants of melanoma cultures, and which were therefore most likely to be melanoma cell surface antigens. The present studies have shown that these blocking factors against melanoma LDA can be detected in patients with primary melanoma, and that the levels of this activity show an inverse correlation with the levels of LDA in the sera of melanoma patients. The appearance of melanoma LDA after surgery for localized melanoma was shown in approximately a third of the patients, and this pattern was shown to result from the disappearance of the LDA blocking activity after surgical removal of the melanoma. Assays were designed specifically to measure the melanoma LDA blocking factors by plasmapheresis. It is not yet known whether the melanoma LDA blocking activity has correlation with tumour growth in melanoma patients. The potential value of measuring this activity to assess response to therapy was shown by studies designed to remove the blocking factors by plasmapheresis. It is not yet known whether the melanoma LDA blocking activity has biological significance in regard to tumour growth, but these studies appear to indicate that measurement of these factors in the sera of melanoma patients may provide a useful in vitro monitor of tumour growth in melanoma patients.

Circulating immune complexes in patients with breast cancer

In a retrospective study in women with breast cancer circulating immune complex levels were measured by radioimmunoprecipitation with 125I-Clq. Before operation all the patients showed plasma immune complex levels significantly higher than those in controls. Twelve months after mastectomy patients identified clinicopathologically as having a good prognosis had almost normal levels of immune complexes. By contrast, patients with detectable dissemination on diagnosis or those who died within 22 months after mastectomy had significantly raised plasma levels. The tumour-specific nature of the immune complexes detected remains to be shown and suggestions about the applicability of this test not only for prognosis but also for monitoring the course of malignant diseases need to be confirmed by further investigations.

Distribution of maternal immunoglobulins in the mouse uterus and embryo in the days after implantation

The distribution of maternal immunoglobulins in the mouse uterus and embryo in the days after implantation has been studied on sections incubated with sheep Fab anti-mouse immunoglobulins labeled with peroxidase. At the time of implantation the blastocyst is already surrounded by immunoglobulins that are also present in the blastocoel and early endoderm; uterine glands contain large amounts of immunoglobulins. Later, immunoglobulins are concentrated in the vacuolated endoderm, then the visceral yolk sac and the embryonic gut. They are also present in the various cavities of the embryo. Trophoblast cells progressively contain increasing amounts of immunoglobulins. In the decidua, immunoglobulins coat the cells and also occasionally appear as cytoplasmic granules. The early presence of maternal immunoglobulins may represent the transfer of serum proteins as a means of nutrition for the embryo. It is also very likely to have an immunological significance in the protection of the embryo.