Serum IgE Antibodies to Cow's Milk Proteins in Children With Differing Degrees of IgE-Mediated Cow's Milk Allergy: Analysis by Immunoblotting

Abstract

ABSTRACT

SDS-polyacrylamide minigel electrophoresis was performed on cow's milk (CM), four purified bovine proteins (α-casein, α-lactalbumin, β-lactoglobulin, and bovine serum albumin), four CM protein hydrolysate infant formulas (Good Start, Ultra Good Start, Alfaré, and Nutramigen), and a soy formula (Isomil). Separated proteins were then electrotransferred to nitrocellulose paper, and immunoblotting for IgE antibodies was performed using the serum from 21 children with IgE-mediated cow's milk hypersensitivity. These children had previously been divided into three groups based on patterns of skin prick test positivity to CM and CM protein hydrolysate formulas: group 1A—positive to CM only, group 1B— positive to CM and whey hydrolysate (Good Start), group 1C—positive to CM, whey hydrolysate (Good Start), and casein hydrolysate (Nutramigen). By history, open challenge, and double-blind, placebo-controlled food challenge (DBPCFC), the children either had topical (group 1A) or systemic (group 1B and 1C) reactions. Immunoblots of sera from these groups of children were compared in terms of the number of different proteins per patient to which they reacted and in terms of the intensity of reactions as determined by a grading scale. There were differences between each group for both parameters, although intensity of reactions to casein most clearly distinguished them from one another. These data further support the subclassification of children with IgE-mediated CM allergy into three skin test groups (1A, 1B, 1C) and two clinical groups (topical immediate reactors and systemic immediate reactors). The data also add further support to previous research by one of the authors (RHS) suggesting that allergists refine their approach to evaluating the CM-allergic child to include skin testing to CM protein hydrolysates as well as to whole CM.