Evaluation of a short term in vitro test for granulocyte chalone activity

Effect of granulocytic chalone on the growth rate of continuous cell lines propagated in vitro: a new assay system

The progress of research on granulocytic chalone has been hampered by a lack of reliable assay systems. This paper reports the use of continuous cell lines growing in liquid suspension culture as a new method for assessing the effect of granulocytic chalone on cell proliferation. Partially purified granulocytic chalone (PPGC) was added to cultures of a rat myeloid cell line (W25), a human myeloid cell line (HL60), a human B lymphocytic cell line (8392), and a human T lymphocytic cell line (8402). The growth rate of the target cell populations was directly assessed by serial cell counts. PPGC pretreatment resulted in a significant inhibition of cell proliferation of the 2 myeloid permanent cell lines, while the growth rate of the lymphocytic cell lines was not affected. Moreover, inhibition of cell proliferation was spontaneously reversed when PPGC treatment was discontinued. Since PPGC from ox leucocytes displayed an inhibitory effect on cell proliferation which was specific to the myeloid cells, spontaneously reversible and not species-specific, it appears to have all the essential properties of a granulocytic chalone.

A flow cytometric in vivo chalone assay using retransplanted old murine JB-1 ascites tumour cells

A flow cytometric in vivo chalone assay is described. Transplantation of old JB-1 ascites tumour cells to new hosts induced an influx of tumour cells, with G1 DNA content, to the S phase. This induction could be reversibly and specifically blocked by injections of an ultrafiltrate of old JB-1 ascites fluid. The method described is superior to a previously published in vivo chalone assay using regenerating ascites tumours. Owing to a reduced variability in time of onset of DNA synthesis, a smaller scatter of observations is achieved and thus the number of mice per group may be reduced using the new method. In contrast to the older technique, the present one does not necessitate killing of mice during the observation period.

Potential pitfalls of [3H]thymidine techniques to measure cell proliferation

Pitfalls and artifacts in the use of [3H]thymidine in the measurement of cell proliferation kinetics in vitro and in vivo are reviewed. These pitfalls are of particular significance for the study of inhibitors of cell proliferation including chalones.

Control of CFUc proliferation by selective endogenous inhibitors

The susceptibility of mouse bone marrow colony forming cells (CFUc) to three different types of proliferation inhibitors in capillary semisolid agar gel was studied. GI-3, a target specific peptide containing granulocyte fraction, T4-1, an oligospecific thymic factor of proteid nature, and the alkylating cytostatics dianhydrogalactitol (DAD) inhibit myeloid colony formation as a function of concentration. The respective MED values amount to 8, 10, and 0.002 microgram/ml. When compared with this same parameter 3H-TdR incorporation into DNA of liquid bone marrow cultures showed a single fold charge for the endogenous inhibitors (GI-3, T4-1) for the cytostatic (DAD) a 3 to 4 fold lower difference. It was demonstrated, that in competitive antagonism of GI-3 and colony stimulating factor the inhibitor prevails over CSF.

Chalone inhibition of granulocyte colony growth in agar: kinetic quantitation by capillary tube scanning

Mouse bone marrow cells were seeded into capillary tubes containing agar with colony stimulating factor. The development of myelomonocytic clusters and colonies was followed by daily tube scanning using their light scattering properties. Three kinetic scanning parameters were determined and the significance of different threshold settings was evaluated; viz. the number of signals, the mean signal height and the signal integrals. The inhibitory effect of two extracts with known granulocyte chalone activity which had been prepared from human peripheral leukocytes and rat bone marrow cells, was followed with the scanning method. A continuous reduction of clusters and colony formation and their growth throughout the incubation period was observed which suggested a sustained retardation of proliferation of both the stem cells committed for myelomonopoiesis and their progeny.