IgE response specific to those molecular regions of casein that contain a major phosphorylation site was analyzed using native and modified caseins and derived peptides. This study included (i) the naturally occurring common variants A1 and A from β- and αs2-caseins, respectively, which were purified in the native form and then dephosphorylated, (ii) a purified rare variant D of αs2-casein which lacks one major phosphorylation site, and (iii) the native and dephosphorylated tryptic fragment f(1–25) from β-casein. Direct and indirect ELISA using sera from patients allergic to milk showed that the IgE response to caseins is affected by modifying or eliminating the major phosphorylation site.
