摘要：

In an effort to clarify the etiology of milk allergy from the standpoint of allergen-specific immune reactions, we investigated the determinants of IgE, IgG4, and T cells specific for bovine αs1-casein from the same individual patients by using its synthetic peptides and cyanogen bromide–digested fragments. αs1-Casein is a major allergen in cow's milk, and its unique conformation enabled us to investigate the determinants of antibodies without consideration about missing the reactivities because of conformational changes. Nine patients were selected as subjects from among 129 milk-sensitive infants screened by ELISA to assess the anti-αs1-casein IgE levels in their sera. By using ELISA for epitope mapping, a C-terminal region of αs1-casein was identified as a common binding site for IgE from all of these patients, whereas those for anti-αs1-casein IgG4 were located in multiple regions of αs1-casein. We determined the specificities of seven αs1-casein–specific T-cell lines established from peripheral blood mononuclear cells of two of the patients. These T cells have been shown to secrete IL-4. All of the T-cell lines had different specificities to αs1-casein. However, a common amino acid residue use was found among the determinants of various T-cell lines from each patient. The results suggest that patients allergic to cow's milk have characteristic B cells recognizing a limited region of αs1-casein and secreting αs1-casein–specific IgE. These B cells may interact particularly with T cells recognizing determinants with a common structure. (J Allergy Clin Immunol 1998;101:660-71)

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