Biomedical Engineering Reference
In-Depth Information
Computer simulations of Eqs. [A1]-[A6] indeed show, not surprisingly, that
monitoring information on progress toward multiple goals can improve immune
performance, in the sense of decreasing average harm E. The system "automati-
cally" adjusts itself for efficient combat when faced by pathogens of varying
virulence. Moreover, even a given pathogen is better handled, compared with
the control "no information model," by secreting N only when it is needed and
turning secretion off when the pathogen threat is no longer serious (4).
I have described a simple model that shows how the deployment of a given
immune system arm (effectors working via noxious chemicals) can use sensed
information to improve performance. This material is summarized in Table 1.
See (4) for a model that illustrates how sensed information can bias an immune
system to choose appropriately among a variety of possible effector arms.
Table 1 . Possible immune system "goals" and how they might be achieved
SENSING GOALS
Goal To be sensed
Identify dangerous pathogen High harm H AND (low noxious N OR
high pathogen P )
Identify harm to self High harm H AND (high noxious N OR
low pathogen P )
PERFORMANCE GOALS
Goal Action
Kill dangerous pathogens Positive feedback to N secretion when
sensors reveal dangerous pathogen and
pathogen killing K
Avoid harm to self Negative feedback to N secretion when
sensors reveal dangerous pathogen and
pathogen killing K
Note . Actuator effect of sensor information is mediated by cytokines.
 
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