4) The Danger Theory
This is an emerging AIS technique based on the notion of Matzinger’s danger model which is growing as an
alternative [9] to negative selection. The vital tenet of classical immunology is the distinction between “self” and
“non-self” cells but still there is no comprehensive distinction between “self” and “non-self” cells. An immune
response is triggered when the body encounters something “non-self”. From Matzinger’s point of view [13] there must
be some bias in differentiating “self” from “non-self” because, for example, there is no immune response for
useful foreign bacteria which are in the food or air.
The central theme of Danger theory is that the immune system responds to danger but not to “non-self”. The motive
for this is that there is no need to attack everything that is foreign. This concept is very practical in WMN environment
and one of the motives for the choice among other AIS models discussed in the literature. In WMN environment,
the danger can be measured in terms of distress signal sent out by un naturally dying nodes/devices in the network.
Figure 2 below illustrates an immune response according to the danger theory. A cell that is in distress sends out a
danger signal, whereupon antigens in the neighborhood are captured by Antigen-presenting cells and then they travel to
the local lymph node and present the antigens to the lymphocytes. Basically a danger zone is established around
itself. Thus B-cells, which are within the danger zone, get stimulated to produce antibodies that match the antigens and