Biomedical subjects

D Ayer

Publications and source records attributed to D Ayer.

3 recordsLinked to original sources

PubMed1991

Growth regulation of the AML-193 leukemic cell line: evidence for autocrine production of granulocyte-macrophage colony-stimulating factor (GM-CSF), and inhibition of GM-CSF-dependent cell proliferation by interleukin-1 (IL-1) and tumor necrosis factor (TNF alpha).

The human leukemic cell line AML-193 was tested for its proliferative response to endogenously produced autocrine factors and to a variety of cytokines and colony-stimulating factors. Cells grown in the absence of GM-CSF incorporated tritiated thymidine, and this was partially reversed by adding neutralizing anti-GM-CSF antibodies to the culture medium, suggesting that it was due, at least in part, to autocrine GM-CSF production. This was confirmed by immunopurification of a GM-CSF-like activity from cell supernatant of AML-193 cells grown in serum free medium in the absence of exogenous GM-CSF. When AML-193 cells were cultured with GM-CSF in combination with other cytokines, Interleukin-1 alpha and beta (IL-1 alpha and beta), Interleukin-3 (IL-3), Interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF) and tumor necrosis factor alpha (TNF alpha), none of them affected the concentration of GM-CSF required to induce 50% of maximum proliferation (D50). However, the maximum proliferation induced by GM-CSF alone was drastically decreased by IL-1 alpha, IL-1 beta and TNF alpha. Inhibition caused by exposure of the AML-193 to IL-1 for up to 24 hr was reversible, ruling out a direct cytotoxic effect.

Cell Division↗

PubMed1986

The context effect does not require a fourth base pair.

The translational activity of a transfer RNA at a codon varies at different message sites, although the codon does not vary. The source of this effect, which may help to determine the level of gene expression, is generally agreed to be in nearby message sequences. By making every possible nucleotide combination between position 33 of the transfer RNA and the major context nucleotide of the message, it was shown that base-pairing between the two nucleotides is not the source of this context effect on translation in vivo.

Anticodon↗

PubMedDate not supplied

Granulocyte-macrophage colony stimulating factor and interleukin-3 regulate the production of an interleukin-1 inhibitor by the differentiated AML-193 leukemic cell line.

Treatment of the AML-193 leukemic cell line with phorbol myristate acetate (PMA) resulted in the loss of their ability to proliferate in response to GM-CSF or IL-3. This was not due to a change in number or affinity of GM-CSF receptors, but possibly resulted from an other cellular mechanism. The AML-193 differentiated cells acquired the ability to phagocytose glutaraldehyde-fixed E.coli in a similar fashion to mature macrophages. In addition the PMA-differentiated AML-193 cells now secreted a factor which specifically inhibited the binding of interleukin-1 (IL-1) to its receptor on the murine thymoma cell line EL-4.6.1C10. The synthesis of this inhibitor was further increased by the addition of GM-CSF or IL-3. Pulse labelling experiments showed that this activity was due to a 26 kDa protein that bound to the IL-1 receptor even in the presence of neutralizing antibodies against IL-1 alpha or IL-1 beta, and this binding was only antagonized by IL-1 alpha or IL-1 beta. In contrast, peripheral monocytes obtained from the blood of normal donors, when induced with either GM-CSF or IL-3, produced large quantities of inhibitor in the absence of PMA. This report clearly shows that a leukaemic cell line can respond to GM-CSF and IL-3 in different ways before and after in vitro differentiation.

Animals↗