Identification of a novel population of CD8 alpha+ beta- bone marrow-derived dendritic epidermal cells. This unique population is subsequently outnumbered by thymus-independent expansion of the CD8 alpha+ beta+ dendritic epidermal cells.
Maturation of some T cell populations has been suggested to occur in epithelial tissues. The CD8 molecule, which is expressed as heterodimers made of alpha/beta-chains on virtually all peripheral T cells, is preferentially expressed as homodimers made only of alpha-chains on a subset of CD8+ mouse gut intraepithelial lymphocytes, which arise from bone marrow (BM) precursors in a thymus-independent mechanism. This unique population of CD8 alpha+ beta- T cells, however, has not been identified in other lymphoid tissues in normal adult mice. Because our previous study demonstrated that reconstitution of thymectomized irradiated mice with T cell-depleted BM cells resulted in the appearance of CD8+, TCR-alpha beta+ dendritic epidermal cells (DEC) and suggested that a proportion of the BM-derived DEC may mature within the epidermis, we asked whether the unique phenotype of CD8 alpha+ beta- could be detected among the CD8+ BM-derived DEC. In this report for the first time we identified this unique population of CD8 alpha+ beta- cells among the DEC. Although this population comprised the predominant fraction of the BM-derived DEC in the early post-transfer period (2 to 3 mo), gradual shift from the CD8 alpha+ beta+ phenotypes occurred during the late post-transfer period (4 to 6 mo) independently of the presence of the thymus. Kinetic studies on the BM-derived DEC revealed that this phenotypic shift could be caused by the subsequent expansion of the CD8 alpha+ beta+ DEC. In contrast, the CD8 alpha+ beta- population was the major subset of the BM-derived intraepithelial lymphocytes throughout the entire observation period and the phenotypic shift with age was never observed. These results indicate that CD8 alpha+ beta- cells are preferentially detected on T cells that home to the epithelial tissues and that in the epidermis, but not in the gut epithelia, the subsequent expansion of the CD8 alpha+ beta+ DEC would dilute the high number of the CD8 alpha+ beta- cells.
Hayakawa
J
J
Department of Dermatology, Kyorin University School of Medicine, Tokyo, Japan.
Shiohara
T
T
Moriya
N
N
Arahari
K
K
Nagashima
M
M
Yagita
H
H
Ishikawa
H
H
D000818:Animals; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D016827:CD8 Antigens / Q000032:analysis*; D003713:Dendritic Cells / Q000276:immunology*; D000078404:Epidermal Cells; D004817:Epidermis / Q000276:immunology; D005260:Female; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*
D016827:CD8 Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta