Wm Ross

The role of dextran sulfate in increasing the CFUc-concentration in dog blood.

Summary Intravenous administration of 10 mg or 15 mg dextran sulfate per kg body weight into dogs results in a marked increase of CFUc in the blood within 3 hr and, to a considerably lesser extent, of mononuclear leukocytes (MNC). The increase after the higher dose is more than tenfold, from less than 200 CFUc/ml blood to about 2000 CFUc/ml, within 3-5 hr; the CFUc gradually decrease thereafter to control levels several hours later. On the other hand, the MNC population experiences a two- to threefold increase which is maintained for several hours. The increase in CFUc after 10 mg/kg is less than after 15 mg/kg, indicating dose-dependence. There is also a cumulative increase observed in the CFUc concentration in blood after repeated injections of dextran sulfate; there is no significant alteration in PMN and MNC levels and there is a slight decrease in the hematocrit and in the thrombocyte level. The mechanism responsible for this phenomenon has not yet been clarified. Due to the probable action of polyanions on cell membranes affecting their adherence capabilities, one may consider both an increased rate of release of CFUc from a marginal or extravascular pool into the blood, as well as a prolongation of the CFUc blood transit time as being contributing factors to the observed blood CFUc increase.

Quantitative aspects of granulocytic progenitor cell (CFUc) mobilization from extravascular sites in dogs using dextran sulphate (DS)

Abstract. The relationship between the increase in the blood CFUc concentration after intravenous injection of dextran sulphate (DS) and the pre‐existing levels of spontaneously circulating CFUc was studied in dogs. After 15 mg DS/kg body weight the CFUc numbers per ml blood rose by a factor of 3.7 over the pre‐injection values, from 78 ± 11 (SEM) to 359 ± 50, in normal dogs, and increased by a factor of 3.9 in 0.84‐Gy‐r‐irradiated animals which had a reduced initial CFUc concentration per ml, from 35 ± 8 to 116 ± 43. The injection of 20 mg DS/kg body weight into unirradiated dogs caused an increase, by a factor of 11.5, of the pre‐injection CFUc concentration, from 101 ± 20 to 921 ± 106. On the basis of the mobilization curves for individual dogs, a significant correlation was found between the normal blood CFUc value and the number of CFUc mobilized by DS for both dose levels. From the descending part of the mobilization curves obtained after 15 mg DS/kg body weight, kinetic parameters of canine circulating CFUc were derived. The mean blood transit time (τ) was 1.4 ± 0.5 hr and the half time (T/2) was 1.0 ± 0.4 hr.

Stimulation of extramedullary hemopoiesis by dextran sulfate

SummaryThe spleen of normal dogs (beagles) shows only slight hemopoietic activity, characterized by the presence of megakaryocytes in mitosis and small groups of erythroblasts scattered throughout the red pulp of the organ. Repeated intravenous injection of dextran sulfate, at a dose of 15 mg per kg body weight, produced markedly enhanced erythropoietic and megakaryocytopoietic activity in the splenic red pulp, without concomitant increase in splenic granulopoiesis. The probable existence of a micro-environment adequate for erythro- and megakaryocytopoietic differentiation of stem cells is discussed.