In other words, this time the rapid influx of a small amount of foreign antigen either triggers an immediate Bilobalide allergic reaction, or else will lead to enough of an immune response that the immune system is primed and develops memory cells against the antigen, causing an allergic reaction upon any subsequent encounters with that same stimulus. Although GDP can be generated by a wide range of different parameter values, certain parameter relationships are required for successful immune defense and, if these parameter relationships are varied, the immune system can become more or less sensitive to different antigen stimulation scenarios. Broadly speaking, for example, decreasing relative to m17 relative to br and b17 will tend to reduce the risk of allergic reaction. While reducing the risk of allergic reaction might seem optimal for successful immune operation, further MK 886 analysis shows that the same changes which decrease allergic tendencies will also lower the sensitivity of the immune system to slow-growing pathogens, leading to a higher risk of chronic infection. This apparent trade-off between the risk of allergic reaction and the risk of chronic infection is one of the less intuitive results of our model and bears an intriguing resemblance to the ��hygiene hypothesis��. According to the ��hygiene hypothesis�� the prevalence of allergies in the westernized world is a result of limited exposure to infectious diseases during early development. Unfortunately, this theory has remained somewhat controversial in part because a mechanistic link between allergies and chronic infection has remained elusive. The GDP paradigm, however, offers a potential explanation for this relationship by highlighting the trade-off associated with defense against slow-growing pathogens and protection against allergic overreaction. In addition to suggesting a mechanism for the hygiene hypothesis, the sensitivity/robustness trade-off that we observe during GDP operation means that there is no perfect set of parameters that can allow for optimal immune system behavior under all antigen stimulation scenarios.