Suppression of graft-versus-host reaction by preincubation of the graft with an antitumor protein, neocarzinostatin

The immunosuppressive activity of neocarzinostatin, an antitumor antibiotic with a high molecular weight, was demonstrated, as measured by the local and systemic graft-versus-host reaction in rats. The preincubation of parental strain lymphocytes with doses more than 1 micrograms/ml of neocarzinostatin for at least 10 min at 37 degrees C resulted in the marked suppression of the popliteal lymph node enlargement, when injected subcutaneously into the hind footpads of F1 hybrid rats. The suppressive effect was temperature-dependent and irreversible, because the neocarzinostatin (1 microgram/ml) pretreatment of parental lymphocytes at 4 degrees C was not effective in the suppressive activity, and the reincubation of cells after the removal of the drug from the culture did not result in demonstrable changes in the degree of suppression. The neocarzinostatin pretreatment does not result in visible changes in the oxygen consumption rate and viability of cells in vitro or in the distribution pattern within a regional lymph node, indicating that treated cells may retain the same viability and migration capacity in vivo as do untreated cells. Furthermore, the drug pretreatment resulted in the complete prevention of runting syndrome, when treated parental lymphocytes were injected intravenously into F1 hybrid rats.

Lymphocytopoietic factor in lymph

The evidences which suggest the presence of a lymphocytopietic factor in rat thoracic duct lymph are summarized briefly. The intravenous injections of the extracted materials from lymph plamsa into syngeneic recipient rats resulted in the massive proliferation of lymphoid cells predominantly in the thymus dependent areas and thymic cortex, suggesting that the target cells for the factor are not marrow-derived (B) cells, but thymus derived (T) cells. The existence of a thymus is not necessarily required for the production or secretion of the factor. The augmenting effect of the factor on T cell functions, eg. local graft-versus-host rection and helper activity of plaque forming response to sheep erythrocytes, is mentioned. The physicochemical characteristics of the factor are nondialysable and heat-stable glyco-protein molecules. The roles of lymph humoral factor in T cell-differentiation or proliferation are discussed.

Studies on lymph humoral factor. Biological characteristics of a lymphocytopoietic factor in rat thoracic duct lymph

The biological characteristics of a lymphocytopoietic factor obtained from rat thoracic duct lymph (Yamashita, Fukumoto & Miyamoto, 1976) were further investigated. The lymph extract from normal rats failed to stimulate both large pyroninophilic cell-proliferation and mitotic response in the spleen and lymph node of the thymectomized, irradiated and marrow reconstituted rat (B rat). This suggests that target or responsive cells for the factor are not marrow-derived (B) cells, but thymus-derived (T) cells. On the other hand, the lymph extract from the lymphopenic lymph-drained B rats showed similar high lymphopoietic activity to those of normal rats, indicating that the existence of a thymus is not essential for the production or secretion of the factor. The fact that lymphocytotic rats produced by syngeneic lymphocyte transfusion are most sensitive to the lymph extract suggests that liver endogenous level of this factor and the responsiveness of target cells are regulated by the number of circulating T lymphocytes.

Nucleosides. 1. 9-(3'-Alkyl-3'-deoxy-beta-D-ribofuranosyl)adenines as lipophilic analogues of cordycepin. Synthesis and preliminary biological studies

A series of lipophilic 9-(3'-alkyl-3'-deoxy-beta-D-ribofuranosyl)adenines of increasing chain length was synthesized from the corresponding branched sugars via titanium chloride catalyzed ribosylation of chloromercuri-6-benzamidopurine. Enhanced growth inhibitory activity was observed against (CCRF-CEM human lymphoblastic leukemia cells in culture as the length of the alkyl side chain in the sugar and the resultant lipophilic character of the nucleoside were increased. Experiments involving incorporation of radiolabeled uridine, thymidine, and leucine revealed that in contrast to cordycepin (1) the 3'-n-butyl and 3'-n-hexyl analogues 5 and 6 markedly inhibit not only RNA synthesis but DNA and protein synthesis as well.

Studies on lymph humoral factor. Evidence for a lymphocytopoietic factor in rat thoracic duct lymph

Normal rats were injected with the partially purified material extracted from the thoracic duct lymph which was collected from normal syngeneic rats. The cellular changes in the peripheral lymphoid tissues and thymus were examined cytologically and histologically. The intravenous injection of the lymph extract into normal syngeneic rats resulted in increase in weight of lymphoid tissues. Histologically, a massive proliferation of large pyroninophilic lymphoid cells and an increase in mitotic index was detected predominantly in the thymus-dependent areas and thymic cortex. In spleens from rats injected with lymph extract, the marginal zone bridging channel was shown as one route for the translocation or mobilization of newly borne lymphoid cells to the venous circulation. Similar lymphocytopoietic activity, but to a lesser extent than lymph extract, was also detected in lymph plasma, serum and serum extract. The lymph extract was shown to be non-immunogenic in syngeneic rats. It is suggested that the effects of the lymph extract on lymphoid cell proliferation are due to the presence of a lymphocytopoietic factor in body fluid, particularly in the lymph.

Subcellular fate of protein antibiotic neocarzinostatin in culture of a lymphoid cell line from Burkitt's lymphoma

14C-LABELED PROTEIN ANTIBIOTIC NEOCARZINOSTATIN (NCS) was prepared efficiently by chemical modification. With the use of lymphoma-derived cell line P3HR-1, the subcellular behavior of this antitumor antibiotic was studied by the uptake a. nd autoradiography of isolated nuclei of radioactive NCS. The antibiotic was taken up by the cells, reaching the maximum value at 1.5 hr and decreasing in value at 4.0 hr to the level at 0.5 hr. The silver grains in the autoradiograms were also found in the isolated nuclei. The grain count in the nuclei showed a tendency similar to the uptake of NCS by the whole cells, i.e., a gradual increase at 0.5 hr, reaching the maximum value at 1.5 hr, and then decreasing after 4.0 hr to the level at 0.5 hr. These facts indicated that NCS reached not only to cytosol but also into the nucleus, and/or at least to the nuclear membrane of the lymphoid cell. The number of NCS molecules incorporated into the cells at 1.5 hr was calculated to be about 1 x 10-6/cells at a concentration of 3 mug NCS per ml of medium, which can be extrapolated to 1 x 10-4 molecules per cell at the minimum inhibitory concentration. The number of molecules should be even less within the nucleus. In cell-free systems, the interaction of DNA and NCS, which is an inhibitor of DNA synthesis, was investigated with use of a Sephadex G-100 column, with negative results. In the cell culture system, NCS molecules were degraded into smaller polypeptides of certain sizes by proteolysis either by serum component(s) or by cells themselves. An inactive isomer, pre-NCS, which is an antagonist of NCS and a partially denatured homologous molecule, behaved similarly to NCS in all of these experiments. Because the chemically modified NCS used in this study retained biological activity essentially similar to that of parental NCS, the results obtained here could be interpreted as similar to those of parental NCS in vitro.

The generation of large pyroninophilic cells in the lymphoid tissues of rats infused with cell-free lymph

The thoracic duct of Wistar strain rats was cannulated during 5 days for studying the effect of selective lymphocyte depletion on the lymphoid tissue. A technique for the continuous infusion of cell-free lymph, whole lymph of Eagle's medium to the rat with the thoracic duct fistula is described in detail. The prolonged drainage of lymph from rats was followed by lymphopenia, sever atrophy of lymphoid tissues and the depletion of small lymphocytes in the thymus-dependent areas of spleen and lymph nodes. The infusion of cell-free lymph into the drained rat resulted in the recovery of the weight of lymphoid tissues and in the massive proliferation and accumulation of large cells with prominent nucleoli and intensely pyroninophilic cytoplasm in the lymphocyte depleted areas of the peripheral lymphoid tissues and thymic cortex. There was histological evidence that the large pyroninophilic cells developed well in the spleen and tended to localize preferentially around the periarteriolar region through the marginal zone bridging channels to the red pulp. The infusion of Eagle's medium was found ineffective in restoring the weight of the lymphoid tissues and in bringing about the proliferation of lymphoid cells. The rats infused with whole lymph showed almost similar findings biologically and histologically to those of sham-operated rats.