Biomedical Engineering Reference
In-Depth Information
4.3
THE COMPLEXITY OF THE IMMUNE
SYSTEM: SCALING LAWS
Alan S. Perelson
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico
Jason G. Bragg
Department of Biology, University of New Mexico, Albuquerque
Frederik W. Wiegel
Institute of Theoretical Physics, University of Amsterdam, The Netherlands
We provide a brief overview of scaling principles for the immune system. Larger animals
tend to live longer than smaller animals and thus their immune systems need to do a bet-
ter job of protecting them. We then ask how the features of the immune system scale with
body mass. A larger animal has more lymphocytes than a smaller one. This implies either
more lymphocyte clones or more cells per clone, or both. The immune system also has
anatomical features such as lymph nodes. Thus, as animals get larger, do lymph nodes
simply get larger or are they more numerous? If appropriate scaling relations can be de-
veloped, they could help us understand the relationship between the human immune sys-
tem and that of other species. A more informed approach to the scaling relationships
among immune systems of different organisms would be nothing but helpful.
1.
INTRODUCTION
The immune system is a complex system responsible for protection against
pathogenic agents. Pathogens can reside in any tissue of the body and the im-
mune system needs to find and respond to them. By necessity the immune sys-
tem is distributed and the cells and molecules that make up the system move or
Address correspondence to: Alan S. Perelson, Theoretical Division, Los Alamos National Labora-
tory, MS-K710, Los Alamos, NM 87545 (asp@lanl.gov).
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