Dietary antigens, epitope recognition, and immune complex formation in recent onset psychosis and long-term schizophrenia.

Peptides derived from dietary antigens such as bovine milk caseins are opioid receptor ligands and contribute to schizophrenia-associated hyperpeptidemia and hyperpeptiduria. The IgG antibody response to bovine caseins is increased in schizophrenia and recent onset psychosis. To identify specific casein peptide sequences that are antigenic in patients vs controls, we measured serum IgG binding to 10-26 amino acid long linear epitopes of casein with immunoassays for the entire group (n=95 recent onset psychosis; n=103 long-term schizophrenia; n=65 control), and with peptide microarray libraries in a casein-sensitive subset (n=14 recent onset; n=10 control).

Subunit and whole molecule specificity of the anti-bovine casein immune response in recent onset psychosis and schizophrenia.

Previous studies show increased antibody levels to bovine casein in some individuals with schizophrenia. The immunogenicity of specific domains of bovine casein varies among people with milk sensitivities and thus could vary among different neuropsychiatric disorders. Using ELISAs and immunoblotting, we characterized IgG class antibody specificity to whole bovine casein and to the alpha(s), beta, and kappa subunits in individuals with recent onset psychosis (n=95), long-term schizophrenia (n=103), and non-psychiatric controls (n=65).