Granulocyte Chalone Assayed <i>in vivo </i>in the Mouse

Abstract

An in vivo system has been developed for estimating the inhibitory activities of granulocyte chalone which overcomes the objection to the use of mixed proliferating target cells. It depends on the identification of labelled mature granulocytes in the peripheral blood of mice that received a radioactive precursor of DNA synthesis, with and without granulocyte extracts, several days previously. Two extracts of bovine granulocytes were tested. The first demonstrated that maximum inhibition was achieved when it was given 2 h before the isotope, suggesting that its activity was short lived. It also failed to depress the labelling index of peripheral lymphocytes, thereby demonstrating tissue specificity. The second was used to show that the dose-response relationship was exponential.

Methods for the Preparation of Purified Granulopoiesis-Inhibiting Factor (Chalone)

“…The factor suppresses myelopoiesis in vitro and in addition has complex effects on hemopoiesis in vivo, mainly expressed as a reduction in the numbers of stem cells committed for myelopoiesis (the authors, in preparation). Analogous biological effects of similar preparations of varying degrees of purity have been described by several other laboratories [8][9][10][11][12][13][14] In this paper emphasis is laid on purification methodology and not so much on assay methods and the examples given merely serve as illustrations. We hope that the chemical methods described here will provide those with a mainly biological interest in chalone-like ganulopoietic inhibitors with preparations whose quality correlates with their intended biological experi-…”