Ontogenesis of rat immune system: Proteasome expression in different cell populations of the developing thymus

• Published in: Cellular immunology 2010, Vol.266 (1), p.83-89
• Main Authors: Melnikova, Victoria I., Sharova, Natalia P., Maslova, Elena V., Voronova, Svetlana N., Zakharova, Liudmila A.
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Antigen presenting cells; Antigen processing; Antigen-Presenting Cells - cytology; Antigen-Presenting Cells - metabolism; Antigens, CD - metabolism; Antigens, Differentiation - metabolism; Antigens, Differentiation, Myelomonocytic - metabolism; Cysteine Endopeptidases - metabolism; Dendritic Cells - cytology; Dendritic Cells - metabolism; Epithelial Cells - cytology; Epithelial Cells - metabolism; Immune proteasome; Immune System - embryology; Immune System - growth & development; Keratin-18 - metabolism; Keratin-19 - metabolism; Prenatal and postnatal ontogenesis; Proteasome Endopeptidase Complex - immunology; Proteasome Endopeptidase Complex - metabolism; Protein Subunits - metabolism; Proteins - metabolism; Rat; Rats; Rats, Wistar; T-Lymphocytes - cytology; T-Lymphocytes - metabolism; Thy-1 Antigens - metabolism; Thymocytes; Thymus; Thymus Gland - cytology; Thymus Gland - embryology; Thymus Gland - enzymology; Thymus Gland - growth & development
• ISSN: 0008-8749; 1090-2163
• DOI: 10.1016/j.cellimm.2010.09.001

Immune proteasomes in thymus are involved in processing of self-antigens, which are presented by MHC class I molecules for rejection of autoreactive thymocytes in adults and probably in perinatal rats. The distribution of immune proteasome subunits LMP7 and LMP2 in thymic cells have been investigated during rat perinatal ontogenesis. Double immunofluorescent labeling revealed LMP7 and LMP2 in thymic epithelial and dendritic cells, as well as in CD68 positive cells – macrophages, monocytes – at all developmental stages. LMP2 and LMP7 were also detected by flow cytometry in almost all thymic CD90 lymphocytes through pre- and postnatal ontogenesis. Our results demonstrate that the immune proteasomes are expressed in all types of thymic antigen presenting cells during perinatal ontogenesis, suggesting the establishment of the negative selection in the thymus at the end of fetal life. The observation of the immune proteasome expression in T lymphocytes suggests their role in thymocyte differentiation besides antigen processing in thymus.