Detection of serum and salivary IgE and IgG₁ immunoglobulins specific for diagnosis of food allergy

Given the growing incidence and prevalence of life-threatening food allergies, health concerns have raised new perspectives for in vivo and in vitro diagnostic methodologies, pointing to saliva as a promising material, already used to diagnose other pathologies. Based on the above considerations, this study aimed to verify the possible use of saliva for the detection of IgE and IgG1 in the diagnosis of food allergy. This was a randomized, cross-sectional clinical study with a quantitative approach, developed at a hospital referral center in allergy in the state of Ceará, from January to July 2015. The sample consisted of 36 children of both sexes, aged between 1 and 60 months, with a diagnosis of cow's milk protein allergy (CMPA) by the RAST test. Children hospitalized or under immunosuppressive drugs were excluded from the study. Serum and saliva samples of the participants were collected and subsequently subjected to the indirect immunoenzymatic assay (ELISA) for the detection of specific serum and salivary immunoglobulins for food: corn, papaya, cow's milk, egg white, wheat, soybeans, peanuts, nuts, kiwi, cacao, fish, shrimp, bananas and tomatoes. For comparison of serum and saliva results, the T-test of independent samples and Mann-Whitney were adopted, for samples with normal and non-normal distribution respectively. A confidence interval of 95% was adopted for significant results. It was observed that 100% (n = 36) of the participants presented cow's milk allergy through the indirect ELISA, detecting IgE or IgG1 in serum and saliva. When serum IgE and IgG1 concentrations were compared, there was no statistical difference (p > 0.05) in 12 of the 14 foods evaluated. The same amount (n = 12) of non-significant differences (p > 0.05) was observed in the comparison of the 14 foods under IgE and IgG1 contractions in saliva. In the verification of the average values of IgE present in the serum and saliva of the foods, only cow's milk, fish and papaya showed statistically significant differences (p < 0.05). Of the total food evaluated, only the average levels of IgG1 present in serum and saliva showed a significant value (p < 0.05) in banana and tomato. These findings indicate that the detection of IgE and IgG1 in saliva proves to be as efficient as in the serum. The use of the salivary technique for use in the diagnosis of food allergy is suggested.鉴于威胁生命的食物过敏发病率与患病率持续攀升，卫生领域的相关关切为体内（in vivo）与体外（in vitro）诊断方法带来了全新视角，其中唾液作为一种已被用于其他疾病诊断的样本材料，展现出良好的应用前景。基于上述背景，本研究旨在探讨唾液在食物过敏诊断中用于检测免疫球蛋白E（IgE）与免疫球蛋白G1（IgG1）的可行性。 本研究为一项采用定量研究方法的随机横断面临床研究，于2015年1月至7月在巴西塞阿拉州的一家过敏专科转诊医院开展。研究纳入36名年龄介于1至60个月的男女儿童，所有受试者均通过放射变应原吸附试验（RAST）确诊为牛奶蛋白过敏（CMPA）。住院治疗或接受免疫抑制药物治疗的儿童被排除出本研究。 研究人员收集了所有受试者的血清与唾液样本，随后采用间接酶联免疫吸附试验（ELISA）检测针对以下食物的血清及唾液特异性免疫球蛋白：玉米、木瓜、牛奶、蛋清、小麦、大豆、花生、坚果、猕猴桃、可可、鱼类、虾类、香蕉与番茄。为比较血清与唾液的检测结果，本研究分别针对符合正态分布与不符合正态分布的样本，采用独立样本t检验与曼-惠特尼U检验进行统计分析，显著性检验采用95%置信区间。 结果显示，所有受试者（n = 36）的血清与唾液样本中均可通过间接ELISA检测出IgE或IgG1，确诊为牛奶蛋白过敏。对14种受试食物的血清IgE与IgG1浓度进行比较后发现，其中12种食物的检测结果无统计学差异（p > 0.05）。在对14种受试食物的唾液中IgE与IgG1浓度进行比较时，同样观察到12种食物的检测结果无统计学差异（p > 0.05）。在比较各食物的血清与唾液中IgE平均水平时，仅牛奶、鱼类与木瓜的检测结果存在统计学差异（p < 0.05）。在所有受试食物中，仅香蕉与番茄的血清与唾液中IgG1平均水平存在统计学差异（p < 0.05）。 上述结果表明，唾液中IgE与IgG1的检测效率与血清检测相当，因此提示唾液检测技术可应用于食物过敏的临床诊断。