Tumor cells cultured in vivo in diffusion chambers induce hematological alterations.

We have studied in BALB/c mice the hematological alterations of the host induced by the growth of tumor cells in diffusion chambers (DC) In this model, host-tumor interactions are only mediated by soluble factors. Tumor cells proliferate and grow in DC up to 15 days after implant. Our results show a reversal of the granulocyte-lymphocyte ratio in peripheral blood, with lymphopenia and a relative increase of myeloid progenitors in the bone marrow of mice bearing DC with M3 tumor cells (M3TC).

Immunomodulation by soluble factors from tumor cells cultured in vivo in diffusion chambers.

The delayed-type hypersensitivity (DTH) response and lymphocyte-mediated angiogenesis were determined in mice bearing in vivo cultures of mammary tumor cells in diffusion chambers (DCs). Soluble tumor products which diffuse from the DCs were able to stimulate the immune system for both the DTH reaction and angiogenic activity by spleen cells.

Mast cells in female mouse lymph nodes.

This study was designed to examine the possible role of sex steroid hormones on mast cells localized in uterus draining lymph nodes (UDLN) in mice. Young virgin estrous animals had more mast cells than diestrous animals in both the UDLN and popliteal lymph nodes (PLN). In retired breeders there were no differences in mast cell numbers of estrous and diestrous animals. There were no differences in mast cell numbers among weanling and older animals in diestrous in the UDLN but, in the PLN, mature animals in either diestrous or estrous had more mast cells than the PLN of weanlings. In mature animals, ovariectomy did not alter mast cell number in either node. However, ovariectomy of weanlings increased mast cell numbers in the PLN but not in the UDLN. These results suggest that the UDLN behaves as a nonclassical target organ for the endocrine system, with mast cell number variations related to gonadal steroid levels.

[Immunoregulation of tumor growth in a murine model]. / Inmunorregulación del crecimiento tumoral en un sistema murino.

Different spleen and tumor cell factors modifying tumoral and metastatic growth were studied. Spleen cell culture supernatants (SCS) from small and large tumor-bearing mice enhanced tumor growth. After tumor surgery, tumor enhancement was only mediated by supernatants from large tumor resected mice. Tumor facilitation and angiogenic response were mediated by the same supernatants; different fractions for these two activities were characterized. T and non-T cells, depending on tumor burden, were responsible for the enhancing activity; but angiogenesis depended only on T cells. While augmentation of metastatic spread was produced by tumor antigens (soluble tumor extracts, tumor-cell supernatants, formolized tumor cells), primary tumor development was not modified by tumor-cell supernatants. Increased incidence of metastases was also mediated by SCS from tumor resected mice which had previously been inoculated with tumor antigens. Immune status of tumor-resected mice was evaluated by delayed-type hypersensitivity reaction. Tumor cell membranes enriched with cholesterol-hemisuccinate were able to increase anti-tumor immune response.

Estrual cycle periodicity in hormone-independent tumor-bearing mice.

The periodicity of the estrual cycle in mice was studied by vaginal cytology during the growth of a hormone-independent mammary adenocarcinoma. A direct relationship between age progression and lengthening of estrual cycle was observed in control mice but not in tumor-bearing mice of the same age. These results suggest that hormone regulation of the estrual cycle may be affected in tumor-bearing hosts.

Inmunorregulación del crecimiento tumoral en un sistema murino. / [Immunoregulation of tumor growth in a murine model]

Different spleen and tumor cell factors modifying tumoral and metastatic growth were studied. Spleen cell culture supernatants (SCS) from small and large tumor-bearing mice enhanced tumor growth. After tumor surgery, tumor enhancement was only mediated by supernatants from large tumor resected mice. Tumor facilitation and angiogenic response were mediated by the same supernatants; different fractions for these two activities were characterized. T and non-T cells, depending on tumor burden, were responsible for the enhancing activity; but angiogenesis depended only on T cells. While augmentation of metastatic spread was produced by tumor antigens (soluble tumor extracts, tumor-cell supernatants, formolized tumor cells), primary tumor development was not modified by tumor-cell supernatants. Increased incidence of metastases was also mediated by SCS from tumor resected mice which had previously been inoculated with tumor antigens. Immune status of tumor-resected mice was evaluated by delayed-type hypersensitivity reaction. Tumor cell membranes enriched with cholesterol-hemisuccinate were able to increase anti-tumor immune response.

Graft-vs-host reaction induced by para-aortic lymph nodes during estrous and diestrous stages.

Mouse uterine draining lymph node (UDLN) cells, or soluble factors released by them in both phases of the estrous cycle were examined in the graft-vs-host (GVH) assay. The immune response during the estrous phase was significantly decreased as compared with diestrous phase; 24-hour culture supernatant of UDLN cells was also able to decrease GVH activity mounted in F1 hybrids. This difference in reactivity was not found when peripheral nodes (PN) or spleen cells were tested. These results show that in physiological conditions it is possible to detect an hormonal influence on T lymphocyte function and would suggest that a non-specific immunosuppression would appear even during the estrous phase.

Enhancement of the incidence of metastasis in tumor-resected mice. Influence of soluble tumor extract and splenectomy.

The M3 mammary tumor was transplantable in syngeneic BALB/c mice, and metastasized spontaneously into the lungs. When primary tumors were resected in early stages of evolution (10 days), the number of mice with lung metastasis decreased. When specific soluble tumor extracts, tumor cell culture supernatant or formalinized tumor cells were inoculated 2 and 4 days after surgery, an enhancement of lung metastasis was observed. When splenectomy was performed at the time of tumor resection, this enhancement was abrogated. These results suggest that tumor plasma cell membranes or the products released by them play an important role in dormant metastases growth, but only in the presence of the spleen, suggesting its involvement in the mechanism of the metastatic process.

Immune reactivity of spleen cells in advanced stages of tumor growth.

In a syngeneic tumor model by an indirect migration inhibition technique, using spleen cells from mice bearing large tumors (ATB-SC) no detectable amounts of migration inhibition factor (MIF) was found in response to either tumor cells or tumor extract. Although lymphokine production was suppressed, ATB-SC were able to respond to exogenous MIF and also to transfer a positive delayed foot-pad reaction (DFR) when co-inoculated with both forms of antigen into normal mice. These observations showed that in advanced stages of tumor development, when the ability of spleen cells to produce MIF toward tumor cells or tumor extract is lost, neither their capability to transfer a positive DFR not their responsiveness to MIF-rich culture supernatants were impaired.

Tumor delayed hypersensitivity reactions. "In vivo" functional differences between spleen and peripheral blood lymphocytes.

In a syngeneic BALB/c transplantable tumor model, specific delayed hypersensitvity reaction, detected by foot-pad swelling test appeared specifically suppressed or "eclipsed" in advanced tumor bearing mice. This "eclipsed" response could not be reversed after tumor resection. Unresponsiveness was analyzed by local adoptive transfer of lymphocytes from two different sources. When spleen cells (SC) from advanced tumor bearing and advanced tumor resected mice were locally transferred into normal recipients, a positive cutaneous delayed hypersensitivity (CDH) reaction was observed. While when peripheral blood lymphocytes (PBL) from the same anergic donors were transferred, no CDH reactivity was elicited. Functional differences between SC and PBL populations are suggested to explain these findings.

Delayed hypersensitivity in tumor-bearing mice. In vitro activation of "eclipsed" spleen cells.

At various stages during the progressive growth of a transplanted sarcoma in BALB/c mice, the delayed hypersensitivity response to tumor antigen was determined using the food-pad swelling test (FPS) and the leukocyte migration inhibition assay (LMI). A close correlation was observed between the in vivo and in vitro assays. "Early" recognition of tumor antigen was detected 24 h after tumor inoculation by both techniques and this positive response was maintained until day 15. As the tumor grew larger, the delayed hypersensitivity response in vivo vanished, while the delayed hypersensitivity response in vitro disappeared about 3 days later. This suppression or "eclipse" of the anti-tumor cellular immune response was specific for the type of tumor used, and could be reversed in vitro by means of a low pH treatment of lymphoid cells.