Changes in passively-sensitized basophil activation to ?S1-casein after oral immunotherapy.
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ABSTRACT: INTRODUCTION:Immune response to cow's milk allergen (CMA) has been analyzed mostly using crude milk antigen or a mixture of various caseins. This study aimed to assess the changes in the immunological response against ?S1-casein during oral immunotherapy (OIT) and to investigate the mechanism of tolerance. METHODS:We have performed rush OIT to 39 patients with CMA and obtained the serum samples up to 3 years after OIT. Immunoglobulin E (IgE) and IgG4 antibodies specific to highly purified ?S1-casein as well as passively-sensitized basophil activation were evaluated using the serial samples. Furthermore, we examined whether basophil activation led by the pre-OIT serum was suppressed by the post-OIT serum, or by the tolerant serum obtained from naturally outgrown patients. RESULTS:Specific IgE to ?S1-casein was significantly reduced after OIT. Specific IgG4 (sIgG4) to ?S1-casein was also detected in most of the pre-OIT sera, which was not significantly increased after OIT. Activation of passively-sensitized basophils to ?S1-casein was significantly reduced after 2 years (14%?±?19%) and 3 years (19%?±?18%) post-OIT compared with pre-OIT (%CD63high basophils; 51%?±?27%). Furthermore, the addition of post-OIT or tolerant serum to pre-OIT serum significantly suppressed the basophil activation. This suppression was abrogated by washing the supernatant after passive sensitization, but not by depleting IgG antibodies from post-OIT or tolerant sera, nor by blocking Fc?RIIb using an anti-Fc?R antibody. CONCLUSIONS:?S1-casein-sIgG4 plays a minor role in tolerance mechanisms in cases of CMA; humoral factors other than antigen-sIgG4 may be involved.
SUBMITTER: Matsui T
PROVIDER: S-EPMC7212200 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
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