Biomedical subjects

F Takei

Publications and source records attributed to F Takei.

117 records · Page 7Linked to original sources

PubMed1978

Characterization of a soluble factor that specifically suppresses the in vitro generation of cells cytotoxic for syngeneic tumor cells in mice.

A tumor-specific soluble factor found in extracts of thymocytes from mice bearing small P815 tumors has been demonstrated. This factor is capable of significantly suppressing the in vitro generation of syngeneic cells cytotoxic for P815 targets if it is added to culture vessels within the first 30 hr of culture. The suppressive factor eluted from Sephadex G-100 after hemoglobin and was estimated to have a m.w. in the range of 40 to 60,000. Preparative isoelectric focusing of thymic extracts established that the suppressive material has an isoelectric point in the range of pH 4.6 to 4.9. The suppressive activity of extracts could be removed by passage of the material through immunoadsorbent columns prepared from membrane proteins of P815 cells but not by analogous columns prepared by using L1210 membrane proteins. The suppressive material was not removed by its passage through immunoadsorbent columns containing anti-mouse immunoglobulin.

Animals↗

PubMed1977

Characterization of suppressor cells in mice bearing syngeneic mastocytoma.

Suppressor cells from syngeneic P815 mastocytoma-bearing DBA/2 mice that inhibit in vitro generation of specific anti-tumor cytotoxicity were characterized. Suppressive activity was almost completely eliminated by treating suppressive spleen cells with anti-theta serum and complement. Treatment with anti-mouse lg serum and complement or with carbonyl iron did not affect their suppressive activity. When suppressive thymocytes from P815 tumor-bearing DBA/2 mice were tested for their capacity to inhibit the generation of cytotoxicity against L1210 cells, a leukemia line in DBa/2 mice, they did not affect the activity, indicating that the supressor cells in the thymocytes of P815 tumor-bearing mice are specific to the tumor. When Ficoll-Hypaque density cell separation was carried out with cytotoxic spleen cells and suppressive spleen cells from 815 tumor-bearing mice, the dense fraction was enriched for kiler cells whereas the suppressive activitty was mainly recovered in the light fraction. Therefore, killer cells and suppressor cells in P815 tumor-bearing mice are thought to be distinct populations.

Animals↗

PubMed1976

In vitro induction of cytotoxicity against syngeneic mastocytoma and its suppression by spleen and thymus cells from tumor-bearing mice.

P815 times 2 mastocytoma cells, when injected subcutaneously into syngeneic DBA/2 mice, induced T lymphocytemediated cytotoxicity in the mice. During the course of tumor growth this cytotoxic activity decreased and ultimately the tumor killed the mice. When spleen cells from mice with tumors in the early stages of growth were incubated in vitro with mitomycin C-treated tumor cells, specific cytotoxicity mediated by T lymphocytes was developed. In contrast, spleen cells, taken from mice with tumors at a later stage in their growth, did not develop cytotoxic activity. The unresponsiveness of spleen cells from mice with tumors in the latter stages of growth seemed to be due to the presence of suppressor cells since in vitro development of cytotoxicity by spleen cells from early tumor-bearing mice were inhibited by the addition of spleen cells or thymocytes from mice with progressively growing tumors. Normal spleen cells or thymocytes did not affect the response.

Animals↗

PubMed1972