The Epidemiology And Mechanism Studies Of Food Hypersensitivity In Children

Food hypersensitivity(FH) is one of the most important health problems in the field of child's nutrition because it often occurs in infants. Although FH has been studied for many years, the mechanisms of it are still unknown. So FH is one of the potential risk factors of child health. In this study, we got the prevalence of FH in 0~24months young children through epidemiology study. To determine the intestinal barrier function in the children with FH, we investigated the intestinal permeability by high performance liquid chromatography(HPLC). With two studies on animals, this paper also obtained the critical period of prophylaxis and studied the mechanisms of FH by histopathology and immunology. The results and conclusions are as follows.1. The prevalence of FH in 0~24months children is about 5.2% and the infants aged 0~12months are more susceptible to have FH.This is the first study on the epidemiology of FH in our country.2. The only effective treatment for FH is to avoid the offending food; The incidence of FH may be decreased by prolonging breast feeding for infants.3. A significant rise in 5-hour urinary L/M excretion ratios was found in FH children(0.18±0.06) compared to that of normal children(0.05±0.03)(P<0.001).The intestinal barrier function was changed in children with FH.This is the first study on the intestinal barrier function of children with FH in China.4. The determination of the urinary lactulose/mannitol(L/M) excretion ratio by HPLC may be a reliable method to evaluate intestinal barrier function in clinical practice.And we are the first to report that 2-hour urine collection may be better for evaluating the intestinal permeability.5. Our study is the first to show that a higher OVA-specific lymphocyte proliferation(stimulation index is 4.40±2.86 vs 1.29±0.22)and a lower capacity to product IFN-γ(66.38±31.12 vs 1293.25±1166.29pg/ml) in the newborn mice were induced by OVA intraperitoneal injection to female mice during the late period of gestation.Therefore, transplacental priming of the fetal lymphocyte(especially T-cell) can be occurred. There was an opportunity for fetus to expose to food antigens during the intrauterine period,and the sensitization period or "window" is postulated as the late of the intrauterine life.6. Transplacental priming favors the development of the allergic phenotype when the mice were exposed to OVA during early life of their birth.7. BALB/c mice may be a suitable animal for studying the onset of FH to OVA upon exposure via enteral route without the use of adjuvants. The level of OVA-specific IgE (0.689±0.439 OD Unit)was increased after 4 weeks sensitization compared to that of the controls(0.235±0.062 OD Unit). The delayed type hypersensitivity responses can be elicited when the mice were sensitized for 6 weeks.This is the first animal model to mimic human FH in China.