The ability of cells to repair cellular radiation damage during the growth of TMT-3 ascites tumor and the effect of host reaction on the repair ability were examined by using an in vitro assay of cell clonogenicity after in situ irradiation of tumor cells. In single-dose experiments, the repair of potentially lethal radiation damage (PLD) was observed in stationary phase cells (12-day tumor) of the unirradiated host, but not in exponential phase cells (3-day tumor) of the unirradiated host animals. However, if previously irradiated host animals were used, even the exponentially growing tumor cells showed repair of PLD. In two-dose experiments, the ability to repair sublethal radiation damage (SLD) in exponential phase tumor cells was less than that of stationary phase cells in the unirradiated host. In the pre-irradiated host, the extent of the repair in exponential phase cells was somewhat enhanced. These results suggest that irradiation of host animals might suppress a factor that inhibits repair, resulting in enhancement of the repair capability of tumor cells.

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Immunofluorescent (IF) staining with monoclonal antibody to O-phosphotyrosine (PTYR) has shown that a variety of human carcinomas (liver, esophagus, stomach, lung, colon and breast) have increased amounts of PTYR-containing proteins (PTYR-proteins), which are localized in cytoplasmic regions and nucleolus-like structures of the carcinoma cells. PTYR-proteins were isolated from carcinomas of the liver, stomach and esophagus, and also from normal regions of these organs by immunoaffinity chromatography with polyclonal antibodies to PTYR. They were then labeled with ¹²⁵I and analyzed by gel electrophoresis. Twenty-eight species of PTYR-proteins in a molecular weight range from 310, 000 to 23, 000 were detected, of which the major 16 species were confirmed to contain ¹²⁵I-labeled diiodo-O-phosphotyrosine residues. All the PTYR-proteins found in carcinomas were also present, though at much lower levels, in normal regions of the respective organs.

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Mouse monocytic Mm-A cells are a highly leukemogenic variant line of the monocytic and non-leukemogenic cell line Mm-1, which developed spontaneously from mouse myeloid leukemia M1 cells. Studies were made on whether Mm-A cells could be induced to differentiate further by agents that were effective for inducing differentiation of the parent M1 cells and other leukemic cells. Of the agents tested, butyrate, conditioned medium from concanavalin A-stimulated spleen cells, lipopolysaccharide (LPS) and N⁶, O²-dibutyryl adenosine 3'5'-cyclic-monophosphate (dbcAMP) significantly stimulated the lysozyme activity of Mm-A cells, which is one of the most characteristic biochemical markers of monocytes and macrophages. Butyrate was the most effective agent for increasing lysozyme production by Mm-A cells; culture with 0.5mM butyrate for 3 days increased lysozyme production by Mm-A cells about 50-fold. Inducers of M1 cell differentiation such as dexamethasone, 1α, 25-dihydroxyvitamin D₃, arginase, and proteinous inducer did not increase the lysozyme activity. Butyrate also induced NBT reduction and stimulated other differentiation-associated functions, such as expressions of Fc receptors on the cell surface, immune phagocytosis and production of inducer for M1 cell differentiation. Its effect in stimulating differentiation of Mm-A cells was synergistic with that of dbcAMP or LPS. Incubation with butyrate inhibited the proliferation of Mm-A cells, about 0.3mM butyrate causing 50% inhibition. These results indicate that monocytic, leukemogenic Mm-A cells can be induced to differentiate further by butyrate and that the inducers of differentiation of Mm-A cells are markedly different from those of the parent myeloblastic M1 cells.

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A human gastric carcinoma cell line TMK-1 was established in vitro by the soft agar method from SC-6-JCK, a poorly differentiated adenocarcinoma xenotransplanted in nude mice. TMK-1 cells had a doubling time of approximately 35hr and showed carcinoembryonic antigen (CEA), α1-antitrypsin and secretory component immunoreactivity. Ultrastructurally, the tumor cells were characterized by numerous mitochondria, tubulovesicles and intracytoplasmic canaliculi filled with abundant microvilli. The growth of TMK-1 cells was promoted by 10nM human gastrin (G-17), 2μM tetragastrin or 2μM pentagastrin, among which human gastrin showed the most effective growth promotion. Moreover, incorporation of [³H]thymidine into TMK-1 cells was stimulated by gastrin in a dose-dependent manner. The content of cyclic adenosine 3', 5'-monophosphate (cAMP) in TMK-1 cells was increased by gastrin treatment but decreased to the control level within 10min. cAMP-dependent protein kinase was also activated by gastrin administration.

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DNA repair in human epidermal cells, a target of skin carcinogenesis, was examined by measuring unscheduled DNA synthesis on autoradiographs. Epidermal cells were obtained from normal subjects and all experiments were performed on primary cultures. UV-irradiation induced unscheduled DNA synthesis in human epidermal cells dose-dependently at doses of 5 to 20J/m². The range of induction varied 3-fold in 9 cultures derived from different donors. No correlation was found between the extent of unscheduled DNA synthesis and the age or sex of the donors. For comparison, human dermal fibroblasts and mouse epidermal and dermal cells were examined under the same conditions. In human dermal cells, the number of grains was about 3.3 times that in epidermal cells. Mouse epidermal cells isolated from newborn C3H/He and Sencar mice showed almost the same extent of unscheduled DNA synthesis as human cells, but the response of dermal fibroblasts of mice was about 2 to 3 times less than that of human fibroblasts. The relevance of these differences among individuals, cell types and species is discussed.

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A lectin reactivity specific to human bowel carcinoma is reported. Twenty-six cases of carcinoma of the large intestine were examined. Normal as well as transitional mucosa and carcinoma tissues were removed from surgical specimens, and paraffin sections were stained with a battery of histochemical methods to characterize glycoconjugates, including high iron diamine-Alcian blue pH 2.5, modified PAS reaction to detect various sialic acids, paradoxical concanavalin A (Con A) staining, and stainings with 10 species of lectins labeled with horseradish peroxidase (HRP). Among the techniques employed, only Griffonia simplicifolia agglutinin-II (GS-II, specific to glucosamine)-HRP staining revealed highly selective affinity to the carcinoma tissues; the apical surface of the carcinoma cells stained most intensely. GS-II reactivity of the cells persisted after prior periodate oxidation, but was significantly enhanced by neuraminidase digestion. Comparison with two other lectin stainings with the same sugar specificity, viz. paradoxical concanavalin A staining and wheat germ agglutinin (WGA)-HRP staining, showed that the GS-II reactive sites lacked class III Con A reactivity but were possibly included in WGA reactive sites. The GS-II-HRP staining should be helpful in the identification of carcinoma tissue and for analysis of carcinoma-associated antigens.

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In order to contribute to the etiological study of thyroid lymphomas, the development of lymphomas in pre-existing chronic thyroiditis was statistically investigated. A total of 5592 female patients (older than 25 years) with chronic thyroiditis diagnosed between 1965 and 1982 at Kuma Hospital in Hyogo Prefecture were followed up until December 31, 1984. From a total of 45623 person-years, 8 new cases of primary thyroid lymphoma were observed (O), all of which were judged to be B-cell type from their immunological or histopathological characteristics. Since the expected number of cases with malignant lymphomas (E1) and the expected number of cases with thyroid lymphomas (E2) were 2.45 and 0.10, respectively, the O/E1 and O/E2 ratios were 3.3 (P<0.01) and 80.0 (P<0.001), respectively. The average follow-up interval for the patients with thyroid lymphoma was 9.2 years. In the reference group, consisting of cases with Basedow's disease, an increased risk of thyroid lymphoma was not observed. The present results suggest that autoimmune reactions with a notable lymphocytic infiltrate may play an important role in the etiology of lymphomas in the thyroid gland.

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Peripheral blood lymphocyte subsets were determined in former workers of the Okunojima Poison Gas Factory (poison gas workers) having a high incidence of lung cancer, and the effect of administration of Nocardia rubra cell wall skeleton (N-CWS) was studied. In poison gas workers not receiving N-CWS, both the percentage and absolute number of Leu-2a⁺ cells were significantly increased as compared with normal controls, while both the percentage and absolute number of Leu-7⁺ cells as well as the Leu-3a/Leu-2a ratio were significantly decreased. In poison gas workers receiving N-CWS, the percentage of Leu-2a⁺ cells was significantly decreased when compared with poison gas workers not receiving N-CWS, while the percentage of Leu-1⁺ cells and both the percentage and absolute number of Leu-7⁺ cells as well as the Leu-3a/Leu-2a ratio were significantly increased. When N-CWS was administered to poison gas workers, the percentage of Leu-2a⁺ cells significantly decreased, with a minimum two weeks after administration, while the percentage of Leu-3a⁺ and the Leu-3a/Leu-2a ratio significantly increased and the percentages of Leu-1⁺ and Leu-7⁺ cells also increased. Furthermore, the absolute number of Leu-3a⁺ cells increased markedly with a peak two weeks after administration. The absolute numbers of both Leu-1⁺ cells and Leu-7⁺ cells as well as total lymphocytes also significantly increased, but that of Leu-2a⁺ cells showed hardly any change. It is considered that a single administration of N-CWS transiently corrects the abnormality of lymphocyte subsets, and that repeated administration of N-CWS once every three months may maintain the lymphocyte subsets of poison gas workers at normal levels.

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C3H/HeN mice were inoculated intravenously (iv) with 10⁶ 10000-R X-irradiated syngeneic MCH-1-A1 fibrosarcoma cells 3 times at 4-day intervals (pretreatment). Spleen cells from these pretreated or normal mice were sensitized in vitro to MCH-1-Al tumor cells and effector cells generated after 5 days of culture were assayed for delayed-type hypersensitivity (DTH) responses by an adoptive transfer into footpads of syngeneic recipient mice together with MCH-1-A1 cells. Normal spleen cells stimulated with MCH-1-A1 tumor cells generated appreciable anti-MCH-1-A1 DTH responses, whereas spleen cells from the above pretreated mice failed to induce anti-MCH-1-A1 DTH responses. These pretreated spleen cells did not inhibit the generation of DTH responses when co-cultured with normal spleen cells as responding cells. Since vaccinia virus-reactive helper T cells are capable of enhancing DTH responses against antigens co-expressed on vaccinia-infected cells, their ability to augment anti-MCH-1-A1 DTH responses from the pretreated spleen cells upon stimulation with vaccinia-infected MCH-1-A1 cells was investigated. The results demonstrate that under conditions in which enhanced anti-MCH-1-A1 DTH responses were obtained by supplementing vaccinia helper T cells, these vaccinia-helpers were not able to generate any significant DTH responses from the pretreated spleen cells. These results indicate that iv inoculation of tumor cells suppresses the generation of tumor-specific DTH responses not by inducing suppressor cell activity, but rather by inhibiting DTH effector clones themselves.

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Human peripheral blood monocytes from healthy donors were separated by discontinuous gradient centrifugation and adherence to yield highly purified adherent cell populations (>99% monocytes). Five different plant lectins were tested for ability to induce lectin-dependent monocyte-mediated cytotoxicity (LDMC). Only one lectin, wheat germ agglutinin (WGA), induced significant and reproducible LDMC activity. All the tumor target cells tested were sensitive to variable extents to cytotoxicity mediated by WGA-treated monocytes. Pretreatment of monocytes with WGA did not result in development of LDMC. N-Acetylglucosamine, which specifically binds WGA, inhibited WGA-dependent monocyte-mediated cytotoxicity. Treatment of adherent monocyte-rich monolayers with monoclonal anti-natural killer cell antibody (anti-Leu-11b) and complement did not affect the LDMC activity induced by WGA. These results indicate that the plant lectin WGA, which binds specifically to both human monocytes and tumor cells, renders human blood monocytes cytotoxic to human tumor cells.

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The antitumor activity of tumor necrosis factor (TNF) against various primarily cultured human cancer cells (32 cases) was investigated by the ⁵¹Cr cytotoxic release assay and the tumor stem cell assay. Over 50% sensitivity (the ratio to the cytotoxicity in L929 cells) was noted in 4 of 14 cases of gastric cancer (28.6%), 7 of 9 cases of leukemic cells (77.8%), and 1 case each of pancreatic carcinoma and ovarian cancer. Scarcely any sensitivity, however, was observed in 1 case of acute promyelocytic leukemia or in some of the gastric cancer cases. No correlation was observed between the histological type of the cancer and TNF sensitivity. The above results seem to confirm that TNF has significant antitumor activity against human cancer cells.

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The effects of two hormonal agents with different mechanisms of action, medroxyprogesterone acetate (MPA) and tamoxifen (TAM), on the tumor growth and hormone receptor status were evaluated in rat mammary tumors induced by 7, 12-dimethylbenz[a]anthracene (DMBA). All estrogen receptor-positive (ER(+)) tumors became ER-negative (ER(-)), and 3 out of 4 progesterone receptor-negative (PgR(-)) and ER(+) tumors became PgR-positive (PgR(+)) after daily, oral administration of TAM for 2 weeks. In contrast, ER and PgR remained unchanged after daily administration of MPA for 2 or 4 weeks. All the ER(+) and PgR(-) tumors were transformed into PgR(+) after daily treatment with MPA for 2 weeks and then with TAM for another 2 weeks, but tumor regression was modest and none disappeared completely. In contrast, complete remission was achieved in all ER(+) tumors in the group treated with TAM for 2 weeks and then with MPA for another 2 weeks. The results suggest that the antitumor activity of the latter treatment regimen was significantly higher than that of the former. The possible mechanisms of antitumor activity of two hormonal agents are discussed.

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