Hematopoietic dynamics in grey collies

Using Lomb periodogram analysis we have quantified variations in the periph eral neutrophil and platelet counts of the cyclical neutropenia animal mode l-the grey collie. We found that the amplitudes of the oscillations in thes e two cell lineages vary concomitantly, Further, the power spectrum and the shape of the oscillations in the absolute neutrophil counts vary together with the amplitude of the oscillations. As the amplitude of the oscillation s increases, the height of the second subharmonic increases, giving rise to a distorted oscillation with two peaks per cycle. The particular dynamics of the absolute neutrophil counts can be reproduced by a combination of a d elayed peripheral feedback, representing the peripheral control of granulop oiesis through granulocyte colony stimulating factor, together with a sinus oidal input representing an oscillatory input from the pluripotential stem cells to the granulocytic lineage. The same pluripotential stem cell input is probably responsible for the sinusoidal oscillations observed in the oth er cell lineages. (C) 1999 International Society for Experimental Hematolog y. Published by Elsevier Science Inc.