6.5.1 Regression in the lymphoid system (LAD).
The allergic response is a primitive, pre-immune defence reaction in higher vertebrates. On a lower level than the more differentiated immune responses, it shares several chemical processes with inflammation and wound-repair, including activation of the complement-system: i.e. rather direct and elementary rescue-responses meant for emergencies, to stop bleeding and to seal off tissue-damage. Parts of the rather explosive complement-system are touched off in an allergic emergency response, in contrast to the more differentiated and subtle responses that immunity supplies (Map 5.2). When over-stimulation by an unmanageable quantity of an antigen prevents proper immunity to develop, the system may regress to an allergic response. The (genetically) vulnerable 15% of humanity is very likely to suffer the consequences of such regression. These people are genetically predisposed to manifest so-called atopic reactions. They will suffer from either allergy (regression in the lymphoid system) or neuroticism (regression in the neuronal system, see next paragraph) or of both. Patients who alternate bouts of eczema and asthma and episodes of tension/anxiety syndrome are not at all rare. People with a more robust genetic constitution can also be affected in this way. Although the probability is much less a regressive reaction may be provoked if the excessive stimulation continues long enough, or if it happens during a temporary lowering of the defence system. Even in the absence of hereditary traits for allergy, a baker for example will sooner or later develop baker's eczema, if the exposure to the allergen is intense enough.