Modelling the Macrophage Invasion
of Tumours:
Effects on growth and composition
AUTHORS:
Markus R. Owen & Jonathan A. Sherratt
Nonlinear Systems Laboratory, Mathematics Institute,
University of Warwick, Coventry CV4 7AL, UK.
ABSTRACT:
Even in the early stages of their development, tumours are not simply a
homogeneous grouping of mutant cells, they develop in tandem with normal
tissue cells, and also recruit other cell types including lymphatic cells
and the endothelial cells
required for the development of a blood supply. It has been repeatedly seen
that macrophages form a significant
proportion of the tumour mass, and that they can have a variety
of effects upon the tumour, leading to a delicate balance between growth
promotion and inhibition. In this paper the authors develop a model for the
early, avascular growth of a tumour, concentrating on
the inhibitory effect of macrophages due to their cytolytic activity.
It is shown that such an immune response is not sufficient to prevent growth,
due to it being a second order process with respect to the density of tumour
cells present. However, the presence of macrophages does have important
effects on tumour composition, and the authors perform a detailed
bifurcation analysis of their model to clarify this. The authors also
consider an extended model which incorporates addition of exogenous chemical
regulators. In this case, the model admits the possibility of tumour
regression and the therapeutic implications of this are discussed.
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