ADCC-MEDIATING CAPACITY IN CHILDREN WITH COWS MILK PROTEIN INTOLERANCE IN RELATION TO IGG SUBCLASS PROFILE OF SERUM ANTIBODIES TO BETA-LACTOGLOBULIN

In a previous study sera from children with cow's milk protein intoler ance (CMPI) exhibiting gastrointestinal symptoms were found to efficie ntly induce antibody-dependent cell-mediated cytotoxicity (ADCC) to be ta-lactoglobulin-coated cells. In contrast, sera from children with co eliac disease showed a low ADCC-mediating capacity, despite high level s of IgG anti-beta-lactoglobulin antibodies. The study described here was undertaken to evaluate whether differences in IgG subclass profile of anti-beta-lactoglobulin antibodies could explain the observed vari ations in the ADCC-mediating capacity. Forty-eight sera from the follo wing groups of children were investigated: CMPI with predominantly gas trointestinal symptoms, CMPI with skin symptoms of immediate-onset, ch ildren with untreated coeliac disease and healthy references. Absorpti on experiments indicated that primarily IgG1 antibodies were responsib le for the ADCC-mediating capacity of the sera. Accordingly, the ADCC reactivity of individual sera correlated with their IgG1 antibody leve ls. Sera from CMPI children with gastrointestinal symptoms, most of wh ich had a high ADCC reactivity, also demonstrated a distinctive subcla ss pattern of their anti-beta-lactoglobulin antibodies with higher rel ative proportions of IgG1 (ratios: IgG1/IgG, IgG1/IgG3 and IgG1/IgG4) than those from the other diagnostic groups. Using logistic regression analysis, the diagnostic potential of ADCC as well as of different Ig G subclass variables for the recognition of gastrointestinal symptoms caused by CMPI was evaluated. The ADCC reactivity of sera was found to be the best predictor in this model.