[Immunopathomorphology of the human placental barrier in the first trimester of pregnancy complicated by the inflammation of the birth-ways].

The effect of ascending infection of birth-ways on transport of maternal immunoglobulins (Igs) through the placental barrier in humans during the first trimester of pregnancy was studied. The transport of Igs is seen already in 3.5-to 5-week-old embryos, and different cellular and biochemical compounds participate at each stage of this process. Transport of Igs through the trophoblast is carried out due to the secretory component (SC) and, perhaps, to some other receptors. Monocytes together with Igs penetrate into capillaries between the endothelial cells and are transported with the blood all over the body. It seems that SC and other receptors help Igs to penetrate into capillaries through the endothelium. Further, Igs are transported with erythroblasts. In the development without infection the transport of IgG was seen in all cases studied. Inflammation of the birth-ways is accompanied by an increase in transport of all Igs, already in early embryogenesis. Three groups were distinguished: 1) abortions without inflammation; 2) cases with signs of moderate inflammation (endometritis, deciduitis); 3) cases with intensive inflammation with necrosis and leucocytic infiltration. Transport of Igs was seen in 77.8% cases of the first group and in all cases of groups 2 and 3. Transport of IgM was not found in the first group, but was seen in 50% cases of group 2 and 66.7% of group 3.

Response of the immune system of mammary tumor-bearing rats to cyclophosphamide and soluble low-molecular mass tumor-associated antigens: the spleen and lymph nodes.

In a previous study, we showed that soluble low-molecular-mass tumor-associated antigens (sTAA) promote the anti-tumor effect of the anticancer drug cyclophosphamide (CPA) on rat mammary carcinogenesis. In this report, we analyzed the underlaying mechanisms. Studies were performed on the spleen and lymph nodes from the following groups of mammary tumor-bearing rats: i) control rats, ii) rats treated with sTAA, iii) rats treated with CPA, i.v.) rats treated with CPA and sTAA. Different zones of the spleen and lymph nodes were measured and their T cell content (CD4(+) and CD8(+) cells) was analyzed immunohistochemically. CPA decreased the size and cell content of follicles, splenic areas related to the production of B cells, of the marginal zone and to a lesser extent of the periarterial lymph sheath, and decreased the number of CD4(+) and, at a lower rate, of CD8(+ )T cells in the spleen. Addition of sTAA restored activity in the splenic zones producing these cells. Similar effects of CPA and sTAA were found in lymph nodes with accumulation of B lymphocytes in the primary and secondary follicles and of T lymphocytes, including both CD4(+) and CD8(+) cells, in the paracortical zone. We suggest that inhibition of the functional activity of the immune system is one of the main reasons for the toxic effects of chemotherapeutic drugs such as CPA and that the tumor-suppressive antitoxic effects of sTAA result from their activation of B- and T-lymphocyte production in this system, particularly in the spleen and lymph nodes.

Soluble low-molecular-mass tumor-associated antigens promote the suppression of rat mammary tumors by tamoxifen and prevent its toxic effect.

This study examined whether the soluble tumor-associated antigens (sTAA) of 66 kDa and 51 kDa could promote suppression of chemically-induced rat mammary tumorigenesis by the hormone-related anticancer drug tamoxifen and prevent the drug's toxic side-effects. Dimethylbenzanthracene (DMBA, 10 mg/rat, 3 administrations) was used to induce mammary tumors in 8-week-old Wistar rats. Then, for 13-17 more weeks, preparations of sTAA (50 microg/rat) and tamoxifen (10 mg/rat) were administered, separately or in combination, on a weekly basis. The experiment was continued for 18 weeks and was terminated when the number of dead rats reached 50% in each group. Treatment with tamoxifen inhibited tumor growth and their malignance: the number of rats without malignant tumors significantly increased compared to controls, 27.3% and 5.6%, respectively. Treatment with sTAA resulted in a significant increase in the number of regressed tumors to 10.1% compared to 0% and 1.4% in control and tamoxifen-treated rats, respectively. Moreover, the period of 50% survival increased from 13 weeks in tamoxifen-treated rats to 17 weeks, and as a result, rats treated with sTAA were involved in the experiment for an average 14.3 weeks compared to 10 and 10.4 weeks in control and tamoxifen-treated groups. In rats treated simultaneously with tamoxifen and sTAA, the time of appearance of each new tumor increased from 4.5 weeks to 6.6 weeks with a significant increase to 14.3% in the number of regressed tumors. The period to 50% survival increased to 18 weeks, and these rats were involved in the experiment for up to 16.4 weeks. The number of rats without malignant tumors increased to 22.2% and the time of appearance of malignancy increased to 9.6 weeks, as compared to 7.3 weeks in controls. The results demonstrated that sTAA have tumor-suppressive properties, and also enhance the anticancer effects of tamoxifen and prevent its toxic side-effects.

Mammary tumors in splenectomized rats.

The objective of this study was to examine how splenectomy affects the immune response, particularly T cells, in chemically-induced mammary tumors. Female rats were splenectomized and then exposed to 9,10-dimethyl-1,2-benz(a)anthracene (DMBA) to induce mammary tumors. Splenectomy significantly decreased the rate of tumor appearance and their malignant transformation. The tumor latency period in splenectomized rats was 12.0+/-0.9 weeks compared to 9.7+/-0.5 wk in intact controls, and malignancy appeared in 45% of splenectomized rats, compared to 70% in controls. By the end of the experiment, the total number of tumors and their size were similar in both groups. Blood CD4+ and CD8+ T cell concentrations were similar in tumor-bearing and tumor-free splenectomized animals, but in both groups CD4- and CD8- lymphocytes decreased sharply compared to control animals. In tumor-bearing rats, splenectomy also resulted in significantly more circulating natural killer cells. The spleens of tumor-bearing control rats had significantly fewer CD4+ and CD8+ lymphocytes and more CD4- and CD8- lymphocytes and natural killer cells than did their blood. In conclusion, splenectomy inhibits the early stages of tumorigenesis and reduces the rate of malignant transformation of benign tumors, but does not prevent the progress of carcinogenesis. Differences between splenectomized (operated) and intact rats to the effect of DMBA can be explained by an increase in non-specific resistance of splenectomized rats as a result of operation.

Stability-variability conflict as a reason for cancer: physical and social aspects.

We present an analysis of cancer based on the synthesis of physical and social models of life as the stability-variability conflict (SVC). We showed that the intensity of the SVC increases with an increase in the rate of evolution or progress of species and populations. The probability of oncogenesis depends on this intensity and on the gray zone in the host's homeostasis. An organism and its cells are two interdependent systems which in extreme situations become antagonistic and competitive. The hierarchy of the biosystems (cell, organism, population) does not resolve the SVC and does not decrease the gray zone of this conflict. Cancer develops mainly due to external effects and results in some internal, including genomic, alterations which result in cell death (apoptosis), or cause cells to begin a new stage in their lives, possibly leading to tumors. In this respect, cancer is a rescuer of the cells, although it brings about the death of the host. An increase in the production of tumor-associated proteins in cancer patients is an example of such changes. Cancer can also be analysed in terms of entropy and information. In the context of the SVC, cancer is irreversible deviations from the "golden mean" solution. The golden mean and cancer deviation are considered universal categories of physical and social reflections of the SVC as the quintessence of life.

An immunohistochemical study of the secretory immune system in human fetal endocrine glands and their precursors.

We examined the presence and distribution of components of the secretory immune system (SIS) in fetal endocrine organs and their embryonic precursors. Specimens from 16 embryos (4 to 8 weeks of development) and 32 fetuses (9 to 38 weeks) were divided into those that had not been exposed to massive foreign antigenic effects (Group I, n=28) and those that had suffered from chorioamnionitis (Group II, n=20). An immunohistochemical study was performed using antibodies against the secretory component (SC), joining (J) chain, IgA, IgM, IgG, subsets of T and B lymphocytes, and macrophages. Positive immunostaining for SIS components in the precursors of endocrine organs was seen from 4 to 6 weeks of development, and was present thereafter in the pituitary body, thyroid, pancreatic islets and adrenals. J chain and immunoglobulins were found in all endocrine cells throughout intrauterine development, but the massive antigenic influence caused by chorioamnionitis decreased the latters immunoreactivity. The presence of SC in the precursors of adenohypophysis and pancreatic islet cells decreased significantly after their transformation into definitive endocrine organs. In the thyroidal follicular epithelium and the pars intermedia of the pituitary body cells, SC was present during the entire period of pregnancy. In adrenals, SC was not found. Maternal immunoglobulins, together with SC and J chain, are accumulated in endocrine gland cells from the early stages of intrauterine life. They are the major mechanism of endocrine cell defense during the early prenatal period when the common immune system is still structurally and functionally incompetent.

The secretory immune system as part of the placental barrier in the second trimester of pregnancy in humans.

The objective of this study was to describe the development of the secretory immune system (SIS) in the placenta of 32 human fetuses who had died from different causes during the second trimester of pregnancy. The distribution of SIS protein elements, including the secretory component (SC), J-chain, IgA, IgM, IgG, as well subsets of lymphocytes and macrophages, were studied by immunohistochemical methods. Both the fetal and maternal parts of the placenta were found to contain these elements. In the fetal part, the immunoglobulins, SC and J chain were located in the syncytio- and cytotrophoblast of the chorion and in the epithelium of the amnion. The villous stroma contained a small amount of different subsets of lymphocytes. Macrophages accounted for up to 45% of the stromal cells of the villi and contained IgG and J-chain. In the maternal part of the placenta, the SIS proteins were in the decidual cells. Relatively few lymphocytes and macrophages were observed in the decidual stroma. Our data suggest that the placenta has two different SIS, one in the fetal part and the other in the maternal part. They differ in their structure and orientation: the maternal SIS protects the mother against paternal antigens from the fetus, while the fetal SIS protects the fetus against macromolecules and infectious agents penetrating from the mother. The placenta represents the largest extracorporal immune system that is functionally active during the whole second trimester of gestation. We suggest that the concept of placental barrier should be expanded to include both fetal and maternal parts of the SIS, fetal membranes and the decidual tissue.

Glass fibers covered with sol-gel glass as a new support for affinity chromatography columns: a review.

The search for mechanical supports for biochemically active compounds serving as immunochemical sensors has been the goal of many studies. A new compound in the form of gel fiberglass (GFG) membranes was recently developed as an example of such supports. In this review, these membranes were analyzed with respect to their use for cancer detection. The membranes are prepared from glass fibers covered with oxysilane to provide a sol-gel glass matrix. Derivatization of the support eliminates nonspecific adsorption. A thin layer of protein trapped in the gel glass during its preparation is deposited on the surface of a lattice of glass fibers. The major innovation of the membrane is its large area. External agents percolating through such a membrane contact a maximal number of molecules of the compounds trapped in the sol-gel glass. As a result, this membrane is highly effective. Each GFG column is built from a series of 20 to 30 membranes. The preparation of such columns is relatively simple, requiring only several hours. The capacity of GFG columns is high: the total amount of tumor-associated antigens (TAA) isolated by these columns from the blood of colon cancer patients reached 50% of the total protein and amounted to up to 9-12 mg/ml of serum. The main components of the isolated TAA were the soluble p66 and p51 proteins. A determination of their concentration by HPLC can be used for early cancer detection. Thus, the described method allows the easy and highly effective isolation of TAA and can be used for different goals, including cancer diagnosis. GFG supports have great potential for the isolation of various macromolecules utilizing specific ligands.

Effects of a 15% orange-pulp diet on tumorigenesis and immune response in rats with colon tumors.

This study evaluated whether the feeding of rats with a 15% orange-pulp diet affects the lymphatic system and the tumorigenic response in rats exposed to a high dose of carcinogen. Five-week-old Sprague Dawley rats were divided into 2 groups fed a control chow diet or the same diet with 15% orange pulp. All rats were injected with 1,2-dimethylhydrazine (DMH) (20 mg/kg) weekly for 6 weeks. At 8 months, tumors, spleens and descending colon were taken from each group for analyses. Feeding rats the 15% orange-pulp diet did not reduce the tumor number but modified the number of adenocarcinomas found in the orange-pulp group compared to controls: 66.7% vs. 93.7%. The number of endophytic tumors was also significantly lower in the experimental group: 6.3% vs. 32.3% in controls. DMH affected the size of the splenic structures. The size of follicles and germinal centers decreased significantly in tumor-bearing rats compared to tumor-free rats. This effect was changed in rats fed the orange-pulp diet. In tumor-bearing rats from this group, only the area of the marginal zone decreased and the red pulp increased compared to tumor-free rats. The size of germinal centers significantly increased compared to tumor-bearing rats in controls. The total number of lymphoid cells decreased in germinal centers of spleens obtained from control tumor-bearing rats compared to tumor-free rats. DMH alone significantly increased the total number of cells in the colon mucosa of the rats fed the control diet. In tumor-bearing rats exposed to the carcinogen and fed the 15% orange-pulp diet, the total number of cells and the number of Ki-67+ cells increased in the depth of tumors whereas the number of CD8+ T cells increased in the colon mucosa, at the border of tumors and its depth. The caspase-3 protein a cysteine protease was elevated in tumors from rats fed the orange-pulp diet. Although the 15% orange-pulp diet did not change the number of tumors in the tumor-bearing rats, feeding rats orange pulp significantly decreased the number of endophytic tumors and increased the number of exophytic tumors. Increased activity of T cell killers in tumors and higher level of proteins involved with apoptosis following consumption of the orange pulp indicate a clear tumor suppressor effect of these dietary fibers.

Transplacental effect of a 15% olive-oil diet on functional activity of immune components in the spleen and colon tumors of rat offspring.

We studied whether feeding pregnant female rats a 15% olive-oil diet affects the activity of lymph cells in the spleen and tumors in offspring with chemically-induced colon tumors. Rat mothers were fed either a 7% corn-oil or a 15% olive-oil diet. Five-week-old male offspring were divided into 3 groups. A control group was fed the 7% corn-oil diet similar to their mothers. The experimental group I was fed the 7% corn-oil diet whereas their mothers were fed the 15% olive-oil diet. The experimental group II was fed the same 15% olive-oil diet as their mothers. Experimental rats were injected weekly for 8 weeks with the carcinogen, 1,2-dimethylhydrazine (DMH), 20 mg/kg b.w. Results of experiments were studied 6 months later. The area of zones in the spleen responsible for producing B and T lymphocytes were measured and the number of cells counted. The activity of lymphoid elements of the spleen and of tumors were studied using immunohistochemical methods for evaluating the synthesis of CD8(+) lymphocytes and proliferative activity of lymphocytes in spleens and tumors. Feeding pregnant or lactating mothers with the 15% olive-oil diet had no marked tumor-protective effect on chemically-induced colon cancer in offspring. Diet-dependent changes were found at the cellular level. In the spleen of control offspring, the presence of a tumor was accompanied by an increase in the number of Ki-67(+) cells and CD8(+) lymphocytes in the red pulp. In experimental group I, DMH significantly increased the total cell number and the number of CD8(+) lymphocytes in the red pulp of the spleen in both tumor-bearing and tumor-free rats. In experimental group II, the total number of lymph cells and the number of CD8(+) lymphocytes increased compared to offspring fed a control diet. Tumor formation activated the proliferative activity of lymph elements. The total number of cells in infiltrates of the colon mucosa decreased in tumor-bearing rats compared to tumor-free counterparts, and this was seen in all three dietary groups of rats. In tumors from offspring of experimental group II, only the number of CD8(+) lymphocytes increased compared to those in offspring of experimental group I. The findings indicate that feeding mothers the 15% olive-oil diet had a cancer-inhibiting role in offspring, predominantly changes at the cellular level.

Soluble low-molecular-mass tumor-associated proteins promote the suppression of mammary tumors by cyclophosphamide.

This study examined whether the soluble tumor-associated-antigens (TAA), of 66 kDa and 51 kDa, could promote suppression by anticancer drugs of chemically-induced mammary tumorigenesis. Dimethylbenzanthracene (DMBA, 10 mg/rat, twice) was used to induce mammary tumors. Then, for nine more weeks, the preparation of TAA and cyclophosphamide (CPA), alone or in combination with TAA, were administered in weekly doses. Twenty weeks after DMBA exposure, the mammary tumor yield was 2.4, 2.8 and 2.9 in the experimental groups compared to 3.5 in the controls. Seventy-five percent of the rats in the control group, but only 37% of TAA, 50% of the CPA, and 30% of the CPA and TAA treated animals had malignant tumors. In the experimental groups, 6.5%, 25% and 38%, respectively, of the tumors regressed, compared to 3% in controls. In the groups receiving CPA or TAA, regression was observed in the fifth week of treatment, and in the group receiving combined treatment, already in the first week. The size of the tumors in control rats increased during the last 10 weeks 3.6 times, in the CPA treated rats 1.15 times, but in those receiving CPA plus TAA it decreased by 0.7 times. The results of our experiment demonstrated that TAA have distinct tumor-suppressive properties, and can enhance the anticancer effects of CPA.

Lymphoid elements and apoptosis-related proteins (Fas, Fas ligand, p53 and bcl-2) in lichen sclerosus and carcinoma of the vulva.

We studied some of the morphological and immunohistochemical parameters of lichen sclerosus (LS) and carcinomas of the vulva in order to verify some characteristics in LS related to neoplasm transformation. Parameters such as proliferating index, rate of proliferation of lymphoid elements into a tumor and types of such elements were studied. In parallel, the number of cells positive to apoptosis-related proteins such as Fas, Fas ligand, p53 and bcl-2 were evaluated. Biopsy material from patients with different vulvar disorders--22 samples with LS and 23 samples with vulvar squamous cell carcinoma (VSCC)--was studied by the methods of morphometry and immunohistochemistry. In LS, the number of T cells is a few times higher than those of B cells. Among the T cells, the number of killers is significantly higher than the number of helpers. Carcinomas, especially those with lymphoid depletion, are characterized by a further significant increase in some parameters such as the rate of lymphoid proliferation and the number of T helpers and killers. The progression in to tumorigenesis was accompanied with a significant increase in the number of Fas+ and FasL+ lymphocytes. In tumor epithelial cells the proliferative index increased in carcinomas with lymphoid depletion. The number of p53+ epithelial cells increased whereas the number of bcl-2+ cells showed a distinct tendency to decrease with progression in to tumorigenesis. Development of a tumor is manifested in deep changes in relationships between different lymphoid components. Only two lymphoid markers are significantly different in VSCC compared to LS: the number of T killers and macrophages. The other parameters studied (rate of proliferative activity, the total number of T cells and T helpers, B cells, IL-2-connective cells) already showed high expression in LS as the first signs of transformation of this inflammation into neoplasia.

Expression of apoptosis and apoptosis-related proteins in microvessels of human ovarian epithelial tumors.

We performed an immunohistochemical analysis of apoptosis and the expression of apoptosis-related proteins (ARP) such as Fas and Fas ligand (FasL), bcl-2 and p53 in human ovarian epithelial tumors. Fas and FasL were abundant in endothelial cells of microvessels, and were observed, at times, in the myocytes of small arteries and veins, in parietal or in obstructive thrombi and fibroblasts. Apoptosis was also noticed in the endothelial cells of capillaries and sinuses. The expression of bcl-2 or p53 was rare. We found that the progression of tumor development was accompanied by considerable changes in the microvessels of ovarian tumors. These changes are probably related to the effect of ARP that are expressed by tumor epithelial cells, lymphocytes and macrophages. We suggest that the ARP are released as a result of necrosis of these cells and are taken up by cells of microvessels and by the cellular remnants of blood clots. The effect of tumors on the microvasculature can be regarded as an angiopathy that results in necrosis and hemorrhage within the tumoral tissue and enhances the progression of the malignancy.

Effect of giant hepatomas on lymphocyte production and secretion of apoptosis-related proteins in the rat spleen.

The effect of extremely large hepatomas on splenic lymphoid elements and apoptosis-related proteins in rats were studied. Hepatoma cells were inoculated subcutaneously into 6-week-old rats, and 4 months later the quantities of T and B cells, macrophages, and cells positive for Fas, Fas ligand (FasL) and interleukin-2 (IL-2) were immunohistochemically evaluated in spleens. Grafting of hepatoma cells caused hyperplasia of the spleen and development of giant tumors that could reach one-third of the rat's body weight. A 7-fold increase in the weight of the spleen was mainly due to proliferation of B lymphocytes and macrophages in the red pulp, while the relative quantity of CD4+ and CD8+ T cells decreased. Extremely small amount of Fas+ and FasL+ lymphocytes were present in the marginal zone, the follicles, red pulp, and occasionally in the PALS. All the splenic zones were abundant with IL-2+ cells, while macrophages and siderophages were present mainly in the red pulp and in the marginal zone of the white pulp. We suggest that all these changes are compensatory processes of the host's lymphatic system.

The interspecies sensitivity to transplacental effects of carcinogens.

Childhood cancer is a serious problem in oncology. Because the period of high sensitivity to environmental effects has been suggested to be early in life, it is thought that a variety of influences on pregnant mothers might result in the development of neoplasia in offspring. Environmental and genetic factors have been shown to play a significant role in modifying transplacental tumorigenesis. To better understand the possible mechanisms governing this phenomenon, an analysis of interspecies sensitivity to the transplacental effect of carcinogens, reviewed herein, should be of interest to many specialists in medicine and biology.

The immune system, apoptosis and apoptosis-related proteins in human ovarian tumors (a review).

Our studies on the relationships among the lymphoid system, apoptosis and apoptosis-related proteins (ARP) in human ovarian benign cysts, borderline tumors, and carcinomas are reviewed and analyzed. Fas and Fas ligand are expressed in 50% to 80% of the epithelial cells in all studied tumors. Many bcl-2-positive tumor epithelial cells are seen in benign cysts and they disappear as tumorigenesis progresses, whereas p53 protein is found only in borderline tumors and in carcinomas. Many exceptions to the opinion that bcl-2 inhibits apoptosis and p53 promotes it are encountered. Bcl-2 is lacking in epithelial cells of mucoid tumors of all grades, and its absence does not stimulate their apoptosis. P53 protein is absent from most lymphocytes, macrophages and epithelial tumor cells, nevertheless, they undergo apoptosis. Indeed, in many tumors apoptosis is regulated without the participation of bcl-2 and p53. Different components of the immune system become active during different stages of tumor development. The weak reaction of T-cell killers and macrophages is typical in benign cysts. In borderline tumors, the activity of T-cell killers increases in the parenchyma, and that of T helpers and macrophages in the stroma. In carcinomas with high lymphoid infiltration, a strong reaction of macrophages and T cell killers in the tumoral parenchyma as well high reaction of T helpers and B lymphocytes in the stroma are typical. Apoptosis that should protect against tumor also stimulates apoptotic death of lymphocytes and macrophages, and this has catastrophic consequences, as seen in weakly infiltrated carcinomas. In conclusion, our studies indicate that during malignancy the major task of the immune system is curtailment and control of tumorigenesis.

Serological markers for detection of cancer (Review).

We reviewed the effectiveness of commercial serological markers for the early detection of cancer and monitoring cancer patients. Parameters, such as specificity and variability of tumor markers were compared with a new approach for cancer detection which was recently developed in our laboratory. We demonstrate that the absence of tumor specificity and the extremely high variability of tumor markers are the reason that none of them can be used for early cancer diagnosis. We developed a method for the isolation of tumor-associated antigens (TAA) and found that two soluble low-molecular mass 66 and 51 kDa proteins could be isolated from the blood of cancer patients. The first protein, albumin, belongs to a group of heat-shock proteins (HSP), while the second is connected with TAA. The progress in cancer is characterized by a relative decrease in the concentration of HSP and a high increase in blood levels of TAA. Our method was shown to be highly sensitive and specific for the early detection of different types of cancer, such as of the colon, uterus, ovary, and breast, as well as melanoma.

Comparative effects of dimethylbenz(a)anthacene and a 15% olive-oil diet on cellular components and expression of apoptosis-related proteins in the spleen and mammary gland tumors of rats.

We compared effects of a high fat diet and a carcinogen on cellular elements of the spleen and mammary gland tumors in rats. Animals were fed a 15% olive-oil diet and a group of them were exposed to a carcinogen, dimethylbenz(a)anthacene (DMBA), in two doses of 10 mg/rat. Results of the experiments were evaluated after 4 months. We studied changes in the areas of different zones of the spleen related to production of B and T lymphocytes and also the number of cells in the spleen and tumors with positive reaction to receptors related to manifestation of apoptosis (FasL and p53) and receptors related to inhibition of apoptosis (bcl-2). In the spleen, dietary fats as well as DMBA alone decreased the zones related to production of B lymphocytes and increased the number of T lymphocytes. The combined effect of a carcinogen and a high fat diet manifested in an increase in the number of lymphoid cells and macrophages. In tumors from rats fed a low-fat diet, an extremely high number of lymphoid cells was seen in the border of tumors with T cell killers as a main component of these infiltrates. In tumors from rats fed a 15% olive-oil diet, the main component of the infiltrates were macrophages. High levels of p53+ and bcl-2+ cells were found in the spleen of rats exposed to a carcinogen. The combined effect of a carcinogen and the 15% olive-oil diet inhibited production of FasL and p53 receptors and stimulated synthesis of bcl-2 protein. In tumors, a carcinogen alone stimulated the high expression of FasL and p53 proteins, but in combination with the 15% olive-oil diet synthesis of these receptors decreased while production of bcl-2 protein increased sharply. This observation may serve as an additional proof of tumor-promoter effects of a high fat diet.

Tumor-induced insufficiency in T cell activity and hyperproduction of interleukin-2 in rat giant hepatomas.

The roles of lymphoid elements and apoptosis-related proteins in the development of extremely large hepatomas were studied in rats. Hepatoma cells were inoculated subcutaneously into 6-week-old rats, and 4 months later the quantities of T and B cells, macrophages, and cells positive for Fas, Fas ligand (FasL) and interleukin-2 (IL-2) were immunochemically evaluated in tumors. Grafting of hepatoma cells caused the development of giant tumors that could reach one-third of the rat's body weight. Within the hepatomas, almost all CD8(+) T cells were destroyed as they passed from the tumoral stroma into the parenchyma and came in contact with tumor epithelial cells. This could be the consequence of IL-2 production, since about 90% of tumor cells were CD25(+). The tumoral mass increased despite the significant increase in tumor necrosis. Cells with Ki67 or in mitosis, and cells positive for Fas and FasL were found only among tumor epithelial cells that were necrotic and never among viable cells. We suggest that progress in tumorigenesis is facilitated by inhibition of T helper cells, and the extensive death of T killer cells is caused by the high levels of the tumor produced IL-2.

Effects of the soluble low-molecular-mass proteins on spleen activity and cellular composition of infiltrates in rat mammary gland tumors.

We showed previously that soluble low-molecular-mass tumor-associated antigens (TAA) could suppress chemically-induced tumorigenesis. In this study, we analyzed the mechanism of those findings. Studies were performed on the spleen and mammary gland tumors obtained from the following groups of rats: i) control rats treated with dimethyl-benz(alpha)antracene (DMBA), ii) vaccinated and carcinogen-treated rats with non regressed tumors, iii) vaccinated and carcinogen-treated rats with regressed tumors. Different zones of the spleen and tumors and their cellular content (Ki67+ and CD8+ cells, and macrophages) were analyzed morphometrically and immunohistochemically. Reaction of the spleen to vaccination was manifested in a significant increase in all areas of the white pulp and in a decrease in the size of the red pulp. The total number of cells in the white pulp (germinal center and PALS) and in the marginal zone was significantly higher in the spleen of rats with regressed tumors. The number of Ki67+ cells decreased significantly in both groups of vaccinated rats, but most prominently in the marginal zone and the red pulp in rats with regressed tumors. An increased number of CD8+ lymphocytes and macrophages was also seen in the red pulp. Different areas of the tumors (peripheral vs. inside at depth) showed different responses to vaccination and this difference was related to conditions of carcinogenesis, i.e. non-regressed vs. regressed tumors. In regressed tumors, all parameters studied were easily distinguishable in both areas of the tumors, while in non-regressed tumors, a marked distinction was seen only at their periphery. In regressed tumors, a negative correlation was seen at depth tumors between the number of Ki67+ cells and the number of CD8+ lymphocytes (r=-0.48). The findings indicated a strict antitumor effect of vaccination with the soluble low-molecular-mass TAA, which prevents the development of insufficiency of the immune system when an intensive immune reaction takes place.