Atopic Dermatitis
Atopic dermatitis is a chronic inflammatory disease of the skin with a genetic predisposition, of unknown origin, the prevalence of which is growing in industrialized countries.
Although in most cases the symptomatology is relatively moderate, atopic dermatitis can be severe and extensive, significantly affecting the quality of patients’ lives (Oranje and de Waard-van der Spek, 2002). Children with atopic dermatitis often have a family history of atopy and show changing symptoms of food hypersensitivity over time.
Children exhibit an increased incidence of food intolerance and allergic manifestations such as rhinitis or asthma (Iacono et al., 1998). Children with atopic dermatitis experience IgG anti-food reactions more frequently that non-atopic children (Eysink et al., 1999). Anti-antigen food-specific IgG are also an early prognostic marker for the development of atopy in children. Subjects with elevated IgG titers to food antigens, most specifically to egg white, orange, mixtures of wheat and rice, run an increased risk of IgG responses to cats, dogs, dust mites, eggs and milk proteins (Eysink et al., 1999; Eysink et al., 2002). Atopic dermatitis is mostly associated with elevated concentrations of anti-beta-lactoglobulin IgG4 (food hypersensitivity) and antibodies to birch (Jenmalm et al., 1999), which implies a deviation of the immune system to a TH2-type reaction in atopic children. The first 6 months of life probably represent a critical period for the initiation of immunological changes, which result in triggering atopy. An exaggerated TH2-type response in high-risk children who will develop atopy is probably due to a reduced production of IFNg and an increased production of IL-4 and IL-10 in the presence of allergens during the neonatal period (Lester et al., 1995; Reinhold et al., 1988; van der Velden et al., 2001). The strong IL-10 response observed in atopic children at age 12 months would result in lack of control of the inflammatory process. Deregulation of genes controlling the expression of TH2 cytokines, excluding cases with a genetic predisposition, would be due to environmental factors before or after birth, given the increasing occurrence of allergies in industrialized countries. Reduction of infectious diseases after vaccination at an early age, antibiotic therapy, and a change in lifestyle and diet, are probably the most important factors that influence an individual’s immune response to antigens or environmental allergens (Parronchi et al., 2000). The balance between the production of TH1 and TH2 cytokines is also influenced by various factors that are present in the microenvironment of CD4 +(TH) cells during their activation (Kapsenberg et al., 1996 ; 1999). Of particular interest is the production level of IL-12 and E2(PEG2) prostaglandin by APC cells, which induces either a TH1 (elevated IL-12) or TH2 (elevated PEG2) response. This level is influenced by the APC cell type, the nature of the stimulus and the presence of certain cytokines (IFNg; TH1; IL-4; TH2).
Guidelines for measuring anti-food IgG antibodies
Since dietary etiology is often implicated in atopic children with a genetic predisposition, the measurement of food-related IgG is useful as a preventive measure in children with a family history. As therapy, a diet based on a profile of intolerances would complement symptomatic treatment of atopic dermatitis.
