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Biomedical subjects

J Sawada

Publications and source records attributed to J Sawada.

At least 109 records · Page 6Linked to original sources
PubMed1980

Effect of puromycin on guinea pig lymphotoxin release and lectin-induced cellular cytotoxicity.

In order to confirm the role of guinea pig lymphotoxin (GLT) in lectin-induced cellular cytotoxicity (LICC), the effect of puromycin, a potent enhancer of GLT activity, on the LICC to target L . P3 cells induced by phytohemagglutinin (PHA) was investigated under serum-free conditions. LICC was completely inhibited by puromycin, when it was added at the initiation of LICC culture, because of the inhibition of the release of GLT from the effector lymph node cells. However, LICC was markedly enhanced when puromycin was added several hours after the initiation of LICC culture. The interpretation of these facts is that GLT release can be inhibited by puromycin, but that the GLT already released exerts an enhanced cytotoxic effect on the target cells in the presence of puromycin. Enhancement of the cytotoxicity by the addition of puromycin several hours after the initiation of LICC culture was observed even after the removal of the GLT present in the supernatant, suggesting that the morphologically intact target cells were already affected by GLT in the early stages of LICC culture.

Animals↗
PubMed1980

Characterization of lectin-induced cellular cytotoxicity mediated by mouse spleen cells and the role of lymphotoxin.

The cellular cytotoxicity mediated by mouse spleen cells in the presence of mitogenic or non-mitogenic lectins was established under serum-free conditions and characterized. Compared with the lectin-induced cellular cytotoxicity (LICC) in the guinea-pig, the activity of lymphotoxin (LT) released into the murine LICC assay cultures was very low. However, a positive correlation was found between the strength of LICC and the LT activity released into the supernatants. Moreover, the addition of puromycin, a potent enhancing reagent of guinea-pig LT activity, markedly promoted the LICC when added 4 h after the initiation of the LICC culture. These data, taken together, suggest that LT acts as an effector molecule in the murine LICC systems as well as in the guinea-pig LICC systems. Properties of the effector cell populations mediating LICC were investigated by depletion of plastic-adherent or nylon-wool adherent cells, by treatment of spleen cells with anti-T-cell sera and complement, and by use of nude mouse spleen cells. The results obtained suggest that both concanavalin A and phytohaemagglutinin-P can induce nylon-wool non-adherent T-cell mediated LICC, phytohaemagglutinin-W was found to be capable of inducing both the nylon-wool non-adherent T-cell mediated LICC and the nylon-wool adherent non-T-cell mediated LICC, the major effector of Bauhinia purpurea agglutinin-LICC was found to be the nylon-adherent non-T-cell population.

Animals↗
PubMed1979

Guinea-pig lymphotoxin resistant L-cell sublines.

Guinea-pig lymphotoxin (GLT)-resistant L-cell sublines were isolated, and the altered properties were characterized. Two of them (No. 1 and No. 2 cells) showed the lowest capacity to absorb GLT and substantially reduced ability to bind labelled Ricinus communis agglutinin (RcA). Both the cell-surface proteins and glycoproteins of No. 2 cells were found to be quite different from those of parental L cells. The glycoprotein of molecular weight 140,000, which specifically bound to RcA-Sepharose, was missing in the No. 2 cells extract. These results indicate that the glycoprotein of molecular weight 140,000 is the most probable candidate for the receptor molecule for GLT, and that No. 2 cells and probably No. 1 cells are GLT receptor-deficient cells.

Animals↗
PubMed1978

Lymphocyte-potentiating factor from human peripheral blood adherent cells.

Low-molecular-weight factor, which can restore the diminished concanavalin A (Con A) response of adherent-cell-depleted human peripheral blood lymphocytes, was partially purified from the culture supernatant of human peripheral blood adherent cells by ion-exchange column chromatography, gel filtration and preparative paper chromatography. This factor apparently has a mechanism of action distinct from that of 2-mercaptoethanol. It affects the cells just before the onset of DNA synthesis possibly as one of the second signals in the Con-A-induced activation of human peripheral blood lymphocytes. However, it was demonstrated that the effective activation of lymphoyctes also required the presentation of Con A by adherent cells to lymphocytes at the triggering stage of the activation, indicating that adherent cells have two distinct functions in the Con-A-induced activation of lymphocytes, i.e. the the presentation of Con A to lymphoyctes and the elaboration of soluble factors.

Animals↗
PubMed1977

Effect of various reagents on the susceptibility of target cells to the cytotoxicity of guinea pig lymphotoxin (GLT).

The cytotoxic activity of guinea pig lymphotoxin (GLT) was increased when the target cells were treated with the following metabolic inhibitors: puromycin, actinomycin D, NaN3, NaF, and 2,4-dinitrophenol, whereas calf serum, N-acetyl-D-galactosamine, colchicine, and vinblastin inhibited GLT-cytotoxicity. Puromycin, an inhibitor of protein synthesis, exhibited the most potent enhancing effect on GLT-cytotoxicity. It seems likely that there are certain cellular metabolic processes depending on cellular protein synthesis which antagonize GLT-cytotoxicity. Taking advantage of this effect of puromycin, a time-saving assay method for GLT-cytotoxicity was developed.

Animals↗