title: Comparison of peptides bound to spleen and thymus class II.
abstract: In the past we and others have suggested that positive selection of developing thymocytes may depend upon interaction between the alpha beta receptors on these cells and major histocompatibility complex (MHC) proteins bound to peptides found uniquely in the selecting tissue, thymus cortical epithelium. To test this hypothesis, peptides were isolated from MHC class II proteins of spleen, thymus cortical plus medullary epithelium, or thymus cortical epithelium alone. The results showed that the major peptides bound to class II on thymus cortical epithelium were also associated with spleen class II. Some peptides could only be detected in isolates from spleen, probably because of differences in the distribution or uptake of the donor proteins between spleen and thymus. Thus, although we found some tissue-specific distribution of self-peptides, our data suggest that there are no fundamental differences among these tissues in the occupancy of class II MHC by self-peptides. These results limit hypotheses which depend on a specialized mechanism of peptide generation and/or MHC class II loading to account for the positive selection of T cells on thymic cortical epithelium.
authors.affiliation: Howard Hughes Medical Institute, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
authors.forename: P
authors.initials: P
authors.lastname: Marrack
authors.forename: L
authors.initials: L
authors.lastname: Ignatowicz
authors.forename: J W
authors.initials: JW
authors.lastname: Kappler
authors.forename: J
authors.initials: J
authors.lastname: Boymel
authors.forename: J H
authors.initials: JH
authors.lastname: Freed
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004848:Epithelium / Q000276:immunology; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000276:immunology* / Q000378:metabolism; D007108:Immune Tolerance; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D008285:Major Histocompatibility Complex; D051379:Mice; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D013154:Spleen / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology; D014018:Tissue Distribution; D014168:Transferrin / Q000737:chemistry / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II; D010455:Peptides; D014168:Transferrin