T and B lymphocyte migration into syngeneic tumors.

The migration of splenic T and B lymphocytes into syngeneic tumors undergoing immunologic rejection was investigates. Spleen cells were obtained from normal BALC/c mice or BALB/c mice bearing tumors induced by murine sarcoma virus (MSV). Either whole spleen cells or immunoabsorbent purified T and B cells were radiolabeled with sodium chromate-51 and injected i.v. into normal or MSV inducted-tumor bearing syngeneic recipients. Twenty-four hours later the recipient mice were sacrificed and radioactivity was assessed for tumor, contralateral normal muscle, the lymph nodes draining the tumor and contralateral draining lymph nodes, peripheral lymph nodes, spleen, and liver. Both T and B lymphocytes from either normal or MSV tumor-bearing animals show greatly increased migration into the tumor when compared with normal muscle. Migration of T cells from both normal and MSV tumor bearers was 30 times that of migration to normal muscle. B cells from tumor-bearing mice, on the other hand, localized in the tumor itself only 50% as frequently as did B cells from normal animals. In addition, T cells from MSV tumor bearers were found in the highest proportion in the lymph node draining the tumor site. We conclude that T and B lymphocytes from either normal or tumor-bearing mice migrate to a syngeneic tumor undergoing immunologic rejection. In contrast, the migration of both T and B cells from tumor-bearing animals was decreased to the peripheral lymph nodes at the time of maximum tumor growth.     

Cell-mediated immune response to syngeneic ultraviolet-induced tumors. II. The properties and antigenic specificities of cytotoxic T lymphocytes generated in vitro following removal from syngeneic tumor-immunized mice.

The immune responses of C3Hf mice to syngeneic fibrosarcomas induced with either ultraviolet light or methychlolanthrene (MCA) were measured in vitro by the ability of cytotoxic lymphocytes (CTL) from immunized animals to kill ⁵¹Cr-labeled tumor targets in a 6-hr assay. The CTL were generated by the in vitro culturing of draining popliteal lymph node (DLN) cells derived from animals that were footpad immunized 8 days previously. It was determined that CTL activity could be generated using DLN from both normal (uv tumorresistant) and uv-exposed (uv tumor-susceptible) C3H mice. The kinetics of CTL generation between these two groups, however, was different in that the lymphocytes from normal animals appeared to differentiate into CTL faster than the lymphocytes from the uv-irradiated mice. The in vitro generation of CTL activity was found to be extremely radiosensitive and was also inhibited by the presence of viable tumor cells within the cell culture. Once generated, it was observed that the CTL were extremely insensitive to the effects of gamma irradiation. It was also established that the CTL is a T lymphocyte that appears to be Ia^?. The CTL derived from mice immunized to syngeneic uv- or MCA-induced tumors were capable of expressing cross-reactive non-MHC-restricted killing of multiple tumor targets. Cold cell inhibition experiments confirmed the presence of cross-reactive determinants on various tumors and also established the presence within a single CTL preparation of effector cells with specificity for both the unique tumor specific transplantation antigens as well as the common (cross-reactive) tumor-associated antigens.     

Enteric migration of radiolabeled lymphocytes.

The migratory patterns of circulating radioisotopically labeled lymphocytes were studied by means of serial transfer into syngeneic recipients. A sub-population of ⁵¹Cr-labeled lymphocytes, defined by their property of additionally labeling with IUDR, was found to possess migrational specificity for the lamina propria of stomach, jejeunum, ileum, and large bowel. This gut-seeking population was found within peripheral nodes, mesenteric nodes, Peyer's patches, thymus, and spleen and consisted of both B and T cells. Labeled lymphocytes homed to intestine during all phases of the cell cycle, suggesting that specificity for the gut is not linked to specific events in the lymphocyte cell cycle.     

Destructive and nondestructive patterns of immune rejection of syngeneic intraocular tumors

Two immunogenic, syngeneic murine tumors were used to analyze the immunopathological processes associated with the immune rejection of primary intraocular tumors. Intracameral inoculation of P91 mastocytoma, an immunogenic variant of P815 mastocytoma, into DBA/2 mice resulted in progressive tumor growth for several weeks before immune rejection eradicated the intraocular neoplasm. The histopathologic characteristics of the tumor rejection included: a) destruction of the vascular endothelium of the microvasculature feeding the tumor; b) ischemic bulk necrosis; c) extensive innocent bystander damage to normal ocular structures; and d) absence of direct inflammatory cell-to-tumor cell contact. Thus, the immunopathological features resembled a delayed-type hypersensitivity (DTH) lesion. A second intraocular tumor model was similarly studied. UV5C25 fibrosarcoma grew slowly in the eyes of syngeneic BALB/c hosts. In sharp contrast to P91 tumors, a mononuclear cellular infiltrate was prominent within the tumor. After 5 wk, the intraocular tumors were completely rejected without detectable damage to normal ocular structures. The rejection of UV5C25 tumors did not produce scar tissue, damage to vascular endothelium, bulk necrosis, or atrophy of the globe. Although tumor-specific cytotoxic T lymphocytes (CTL) and DTH responses were readily detected, there was no histological evidence for DTH-mediated tumor rejection. Moreover, in situ immunoperoxidase staining indicated that the majority of the infiltrating lymphocytes were CTL, based on their characteristic phenotype: Thy-1+, Lyt-2+. Furthermore, the growth of UV5C25 fibrosarcoma in athymic, natural killer (NK) cell competent BALB/c nude mice demonstrated progressive tumor growth without infiltrating host cells. Collectively, the results indicate that immunogenic intraocular tumors can undergo strikingly different patterns of immune rejection with profoundly different pathological consequences. In one case (P91), tumor rejection occurs by a process that strongly resembles DTH and produces extensive nonspecific damage to normal tissues, resulting in irrevocable loss of vision. In contrast, the second intraocular tumor undergoes an immune rejection that is characterized by precision and a notable absence of damage to normal ocular tissues. The weight of evidence presented here strongly supports the hypothesis that the latter form of tumor rejection is mediated by CTL. Thus, the immunologic pathway invoked for tumor rejection in the eye has a profound effect on the fate of this delicate organ and the preservation of vision.     

Selective localization of radioiodinated alkylphosphocholine derivatives in tumors

We have designed and synthesized two radioiodinated analogs of hexadecylphosphocholine in order to evaluate their tumor imaging potential. 12-(m[¹²⁵I]iodophenyl)dodecyl phosphocholine (NM-324) and hexadecyl-2-[N,N-dimethyl-N-(m[¹²⁵I]iodobenzyl-ammonium]ethyl phosphate (NM-326) demonstrated the ability of such compounds to localize in and thereby visualize the Walker 256 tumor in rats. However, the tumor avidity of NM-324 was far superior to NM-326. In addition, NM-324 showed excellent tumor localization in athymic mice bearing subcutaneous human tumors.     

In vitro reactivity of splenic lymphocytes from normal and UV-irradiated mice against syngeneic UV-induced tumors.

Skin tumors induced in mice by chronic ultraviolet (UV) irradiation are highly antigenic and are frequently immunologically rejected upon transplantation to normal syngeneic recipients. In this study we characterized this immune response with an in vitro microcytotoxicity test. Cytotoxic activity was present in the spleen cells of mice given a single injection of syngeneic UV-induced fibrosarcoma cells. After removal of adherent spleen cells, the remaining splenic lymphocytes were specifically cytotoxic for the immunizing tumor and showed no cross-reactivity with other syngeneic UV-induced or methylcholanthrene-induced tumors of similar histologic type. The level of cell-mediated reactivity against UV-induced tumors was quite high compared to that obtained with syngeneic tumors induced by methylcholanthrene, and the cytotoxicity was attributable to a population of theta antigen-bearing lymphocytes. With this in vitro test, we compared the response of normal mice, which reject a syngeneic tumor challenge, with that of UV-irradiated mice, in which the syngeneic UV-induced tumors grow progressively. After tumor cell inoculation, lymphocytes form the unirradiated (regressor) mice showed a high degree of cytotoxicity that reached a maximum level 8 days after injection. In contrast, no reactivity could be detected in the spleens of tumor-challenged UV-irradiated (progressor) mice.     

Somatostatin receptor imaging in vivo localization of tumors with a radiolabeled somatostatin analog

This paper presents the results of the visualization of somatostatin (SS) receptor positive tumors in man after the i.v. administration of the SS analog Tyr³-octreotide coupled to ¹²³I. It is an easy, quick and harmless procedure which allows imaging of primary and (often unexpected) secondary deposits and/or multiple localizations of the majority of endocrine pancreatic tumors, metastatic carcinoids and pituitary tumors, as well as of a multitude of humors with neuroendocrine characteristics and well-differentiated brain tumors and meningiomas. In the case of hormone-secreting tumors a positive scan in most instances also predicts the subsequent successful therapy with octreotide.     

Somatostatin receptor imaging in vivo localization of tumors with a radiolabeled somatostatin analog

This paper presents the results of the visualization of somatostatin (SS) receptor positive tumors in man after the i.v. administration of the SS analog Tyr³-octreotide coupled to ¹²³I. It is an easy, quick and harmless procedure which allows imaging of primary and (often unexpected) secondary deposits and/or multiple localizations of the majority of endocrine pancreatic tumors, metastatic carcinoids and pituitary tumors, as well as of a multitude of humors with neuroendocrine characteristics and well-differentiated brain tumors and meningiomas. In the case of hormone-secreting tumors a positive scan in most instances also predicts the subsequent successful therapy with octreotide.     

Effector phenotypes and mechanisms of antitumor immune reactivity of tumor-immunized and tumor-bearing mice in two syngeneic tumors.

By using two different syngeneic tumors, Meth A sarcoma and RL male 1 lymphoma of BALB/c origin, the present study was designed to investigate the subset(s) of T cells mediating in vivo antitumor immune responses and some of the effector mechanisms of in vivo protective immunity in BALB/c mice immunized against tumor or bearing tumor. Spleen cells from the mice immunized against Meth A tumor or bearing Meth A tumor inhibited the growth of Meth A tumor in the Winn assay. In the Meth A-immunized mice, L3T4+ (CD4+) cells played a major role in mediating the inhibitory activity against Meth A tumor growth, whereas in the Meth A-bearing mice, the antitumor protective immunity was mediated by both L3T4+ and Lyt-2+ (CD8+) cells. Spleen cells from the Meth A-immunized or Meth A-bearing mice were not able to generate cytotoxic T lymphocytes (CTL) directed against Meth A tumor after the in vitro restimulation of spleen cells with mitomycin C (MMC)-treated Meth A cells, while fresh spleen cells from the Meth A-immunized or Meth A-bearing mice were able to induce the strong delayed-type hypersensitivity (DTH) responses to Meth A tumor. The DTH response to Meth A tumor was mediated by L3T4+ cells in the Meth A-immunized mice and by both L3T4+ and Lyt-2+ cells in the Meth A-bearing mice. In the similar experiments performed in the RL male 1 lymphoma, the antitumor activity in spleen cells from the RL male 1-immunized or RL male 1-bearing mice depended on Lyt-2+ but not L3T4+ cells in the Winn assay. When spleen cells from the RL male 1-immunized or RL male 1-bearing mice were cultured with MMC-treated RL male 1 cells for 5 days, an appreciable CTL response to RL male 1 tumor was induced. These results suggest that the nature of tumor and/or tumor antigens determines which T cell subset is required to exhibit the protective immunity against tumor and thus the different effector mechanisms could be induced in the different tumor models. Furthermore, these data support the conclusion that antitumor T cell responses are affected by the immune state of host to tumor.     

Fate of H2-activated T lymphocytes in syngeneic hosts. III. Differentiation into long-lived recirculating memory cells.

Memory to H2 determinants was studied with an adoptive transfer system using a population of H2-activated blast T cells (T.TDL) obtained from thoracic duct lymph of irradiated F₁ hybrid mice injected with parental strain T cells. CBA T.TDL activated either to DBA/2 or C57BL determinants were transferred to syngeneic “B” mice. Thoracic duct lymphocytes (TDL) were obtained from the recipients 4–6 weeks later and tested for their capacity to produce (a) a graft-versus-host (GVH) reaction, (b) a mixed lymphocyte reaction (MLR) (measured by an in vivo technique) and (c) allograft rejection (suppression of the growth of allogeneic tumour cells in vivo). Control experiments involved testing the function of TDL obtained from “B” mice preinjected with TDL or no cells.TDL from “B” mice injected with TDL (passaged TDL) gave strong MLR and GVH reactions to both DBA/2 and C57BL determinants. Passaged T.TDL activated to C57BL antigens gave intermediate MLR and GVH reactions to the specific (C57BL) determinants but only very low responses to third-party (DBA/2) determinants; reciprocal results were obtained with passaged T.TDL activated to DBA/2 determinants. TDL from “B” mice given no cells failed to respond to either set of determinants.Since the responses by the passaged T.TDL did not exceed those by passaged TDL there was no evidence that adoptive transfer of T.TDL had conferred to the recipients a state of memory to either MLR or GVH determinants. Adoptive transfer did, however, lead to qualitative changes in the properties of T.TDL since, before transfer, they were unable to evoke GVH reactions or produce an MLR of normal kinetics.Passaged T.TDL were far superior to passaged TDL at suppressing the growth of allogeneic tumour cells. The protection was specific since protection against DBA/2 tumour cells was, cell for cell, 5–10 fold more effective with passaged T.TDL activated to DBA/2 determinants than with cells activated to C57BL determinants. No protection was observed with cells treated with anti-θ serum. The protective cells appeared to be precursors of effector cells rather than effector cells per se since they failed to lyse the tumour cells in vitro. These data suggest therefore that the descendants of T.TDL which survived after transfer to “B” mice were highly enriched in long-lived recirculating T lymphocytes reactive to determinants expressed by specific tumour allografts.     

Stimulation of lymphoid cells from normal and immune mice by syngeneic BALB/c plasma cell tumors.

Lymphoid cells from normal and immunized BALB/c mice could be stimulated in vitro by syngeneic PCT contrasted with an absence of response to a number of other tumors. Maximal responses of normal cells to PCT were found to occur 5 days after the initiation of the cultures at an optimal responding:stimulation cell ratio of 1:2. MLTI activity of normal cells could not be blocked or enhanced by PCT myeloma protein products indicating that MLTI reactivity was directed against non-idiotypec cell surface determinants. Lymphoid cells from immunized mice demonstrated increased MLTI responses to cells of the immunizing tumor but not to other PCT, indicating that the post-immunization MLTI responses were primarily to individual rather than shared tumor cell surface antigens. Activity of both normal and immunized spleen cells was found to involve thymus-derived lymphocytes. The persistence of residual MLTI activity after treatment with anti-theta serum and complement, however, implicated participation of non-theta antigen-bearing cells in MLTI reactivity. From these data, we conclude that lymphoid cells from un-immunized mice are capable of T cell-dependent reactivity to syngeneic PCT-associated antigens and that elevations in these reactivities after immunization may reflect specific cellular immune responses.     

Autoimmune reactions against liver cells by syngeneic neuraminidase-treated lymphocytes.

We have found that the entrapment of neuraminidase-treated lymphocytes in the liver leads to the induction of autoimmune cellular cytotoxic reactions. Lymphocytes from mouse spleen and thymus were incubated with neuraminidase in vitro and injected i.v. into syngeneic recipients. Lymphocytic infiltrations into the liver were seen 7 days later with both types of cells. After repeated weekly injections of asialo-lymphocytes, destruction of liver tissue became apparent. Electron-microscopic studies showed that hepatocytes, fat storage cells, and endothelial cells were affected, mainly at the hepatic periphery. It is concluded that the adhesion of asialo-lymphocytes to liver cells induces their cytotoxic activity. Similar reactions may occur after paramyxovirus infection due to the action of viral neuraminidase.     

Cell-mediated immune response to syngeneic UV induced tumors: I. The presence of tumor associated macrophages and their possible role in the in Vitro generation of cytotoxic lymphocytes

A primary in vitro sensitization system employing a chromium release assay was utilized to investigate reactivity of murine spleen cells toward syngeneic ultraviolet (uv) light induced fibrosarcomas. These tumors are immunologically rejected in vivo when implanted into normal syngeneic mice but grow progressivly when implanted into syngeneic mice that had previously been irradiated with subcarcinogenic levels of uv light. Following appropriate sensitization, spleen cells from both normal and uv irradiated mice are capable of developing cytotoxic lymphocytes in vitro against the uv induced tumors. It was subsequently discovered that in situ uv induced tumors all contained macrophages of host origin that became demonstrable only after enzymatic dissociation of the tumor tissue. These macrophages were immunologically active in vitro as their presence in the stimulator cell population was necessary to achieve an optimum anti-tumor cytotoxic response following in vitro sensitization. Anti-tumor reactivity generated by mixing spleen cells and tumor cells in the absence of tumor derived macrophages could be greatly enhanced by the addition of normal syngeneic peritoneal macrophages. When in vitro anti-tumor reactivity of spleen cells from normal and uv treated mice was compared under these conditions we again found no significant difference in the magnitude of the responses. In addition, the cytotoxic cells generated in response to uv induced tumors appeared to be highly cross reactive with respect to their killing potential. Cross reactive killing was observed between all uv induced tumors tested as well as with a syngeneic benz[a]pyrene (BP) induced fibrosarcoma. No cytotoxicity was observed against normal syngeneic PEC's even through these cells were shown to be susceptible to lysis by anti-H-2^k effector cells. It was concluded that: (a) A significant number of host-derived macrophages are present in uv tumor tissue. (b) These macrophages are important for the in vitro generation of tumor specific cytotoxicity. (c) Spleen cells from uv treated mice are capable of recognizing and responding against uv tumor associated antigens in vitro. Cytotoxic effector cells generated in response to uv induced tumors appear to have specificity for tumor associated antigens (TAA) present on all uv tumors tested as well as a syngeneic BP induced tumor. The relationship between in vivo and in vitro reactivity against uv tumors is discussed.     

The induction of cytolytic T lymphocytes with syngeneic trinitrophenyl-coupled membranes.

Evidence is presented that trinitrophenyl-coupled tumor membranes are able to induce cytolytic T lymphocytes (CTL) when co-cultured with syngeneic spleen cells. These haptenated membranes stimulate spleen cells from naive and immune mice. The specificity of these CTL is determined by the H-2 antigens of the membranes used for stimulation.     

Nonspecific activation of murine lymphocytes. II. Parameters of the interaction between splenic lymphocytes and radiolabeled 2-mercaptoethanol in vitro.

Recent evidence has indicated that addition of 2-mercaptoethanol (2-ME) to culture medium is able to activate murine lymphocytes to undergo blastogenesis, to synthesize polyclonal antibody, and to develop cytotoxicity to both autologous and heterologous target cells. In order to explore the basis for these phenomena, a study of the physical interaction between the cell and 2-ME was undertaken by using a radiolabeled preparation of 2-ME. Uptake of labeled 2-ME increased over the initial 24 hr of culture, after which a steady state was achieved. Cells were found to have maximal susceptibility to activation by 2-ME after incubation for 24 hr in the absence of the thiol compound. This observation was not explicable in terms of any alteration in the kinetics of 2-ME uptake. The amount of labeled 2-ME taken up was a function of the 2-ME concentration with which the cell was incubated, with the exception of the concentration range that is optimal for mitogenesis. At this range, the curve was suggestive of a saturation effect. Uptake by B cell cultures was found to exceed that by T cell cultures. Uptake was shown to result from interaction with protein, to be independent of metabolic energy, to be governed by temperature-dependent kinetics, and to be highly specific.     

Intracellular localization of anti-tumor immune RNA.

Syngeneic spleen cells from normal, non-immune Fischer 344/N rats and allogeneic spleen cells from normal Wistar-Furth rats became cytotoxic, in vitro, to chemically induced Fischer rat sarcoma (MC3-R) target cells following incubation with xenogeneic Immune RNA (I-RNA) extracted from spleens of guinea pigs immunized with MC3-R tumor cells. I-RNA extracted from intact spleen cells or from the cytoplasmic fraction of spleen cells were equally active. RNA extracted from isolated spleen cell nuclei was inactive, as were all RNA fractions from spleen cells of nonspecifically immunized guinea pigs. Syngeneic I-RNA extracted from intact spleen cells or the cytoplasmic fraction of cells from spleens of Fischer rats bearing growing MC3-R transplants mediated cytotoxic reactions against MC3-R target cells when incubated with normal Fischer rat spleen cells. RNA from the nuclei of spleen cells of rats bearing MC3-R tumors was considerably less active. All RNA fractions from spleen cells of normal non-immune Fischer rats were inactive. The immunologically active component of xenogeneic and Syngeneic I-RNA, therefore, were found to be localized in the cytoplasm of specifically sensitized lymphoid cells.