Adjuvants, Immunologic/pharmacology; Celiac Disease/immunology; Glutens/immunology; Interleukin-15/immunology; Tretinoin/pharmacology; Administration, Oral; Adolescent; Adult; Animals; Celiac Disease/chemically induced; Celiac Disease/etiology; Cells, Cultured; Child; Child, Preschool; Coculture Techniques; Dendritic Cells/drug effects; Dendritic Cells/enzymology; Dendritic Cells/immunology; Dendritic Cells/metabolism; Diet; Forkhead Transcription Factors/metabolism; Gliadin/administration & dosage; Gliadin/immunology; Glutens/administration & dosage; HLA-DQ Antigens/genetics; HLA-DQ Antigens/immunology; Humans; Immune Tolerance/drug effects; Inflammation/immunology; Interleukin-12/biosynthesis; Interleukin-12/immunology; Interleukin-12/metabolism; Interleukin-15/genetics; Interleukin-23/immunology; Interleukin-23/metabolism; Intestinal Mucosa/cytology; Intestinal Mucosa/immunology; Mice; Mice, Inbred C57BL; Mice, Transgenic; Middle Aged; Mitogen-Activated Protein Kinase 8/metabolism; Phosphorylation/drug effects; Receptors, Interleukin-12/deficiency; T-Lymphocytes, Regulatory/cytology; T-Lymphocytes, Regulatory/drug effects; T-Lymphocytes, Regulatory/immunology; T-Lymphocytes, Regulatory/metabolism; Tretinoin/immunology; Young Adult