Human thymus contains 2 distinct dendritic cell populations.
In this study, 2 distinct populations of mature dendritic cells (DCs) were identified in the human thymus. The major population is CD11b-, CD11c+, and CD45RO(low) and does not express myeloid-related markers. It displays all the characteristics of mature DCs with a typical dendritic morphology, high surface levels of HLA-DR, CD40, CD83, and CD86, and expression of DC-lysosome-associated membrane glycoprotein messenger RNA (mRNA). In addition, CD11b- thymic DCs do not express macrophage inflammatory protein-1alpha (MIP-1alpha) mRNA, but express thymus-expressed chemokine (TECK) mRNA and are able to secrete bioactive interleukin 12 (IL-12) upon stimulation. In contrast, the minor and variable thymic DC population is CD11b+, CD11c(high), and CD45RO(high) and comprises CD83+CD14- mature and CD83- CD14+ immature DCs. It expresses macrophage-colony stimulating factor receptor, MIP-1alpha mRNA and high amounts of decysin mRNA after CD40 activation, but does not express TECK and is a weak bioactive IL-12 producer. Also identified were the IL-3Ralpha(high) plasmacytoid cells, which are present in the thymic cortex and medulla. Upon culture with IL-3, granulocyte/macrophage-colony stimulating factor, and CD40 ligand, the plasmacytoid cells can adopt a phenotype resembling that of freshly isolated CD11b- thymic DCs. However, these plasmacytoid-derived DCs fail to secrete bioactive IL-12; therefore, conclusions cannot be made about a direct relation between thymic plasmacytoid cells and CD11b- DCs. Whereas CD11b+ thymic DCs appear to be related to tonsillar germinal-center DCs, the major CD11b- IL-12-secreting human thymus DC population has similarities to mouse CD11b- CD8+ DCs.
The Walter and Eliza Hall Institute of Medical Research, P.O. Royal Melbourne Hospital, 3050 Melbourne, Victoria, Australia. vandenabeele@wehi.edu.au
S
S
Vandenabeele
H
H
Hochrein
N
N
Mavaddat
K
K
Winkel
K
K
Shortman
D000818:Animals; D023201:CD40 Ligand / Q000494:pharmacology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D018929:Cell Culture Techniques; D002469:Cell Separation; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007118:Immunoassay; D016130:Immunophenotyping; D018664:Interleukin-12 / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000235:genetics / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology*
D016177:Macrophage-1 Antigen; D012333:RNA, Messenger; D023201:CD40 Ligand; D018664:Interleukin-12