The Journal of Immunology, Vol 150, Issue 10 4323-4330, Copyright © 1993 by American Association of Immunologists

ARTICLES

Bone marrow-derived dendritic epidermal T cells express T cell receptor- alpha beta/CD3 and CD8. Evidence for their extrathymic maturation

T Shiohara, N Moriya, J Hayakawa, K Arahari, H Yagita, M Nagashima and H Ishikawa
Department of Dermatology, Kyorin University School of Medicine, Tokyo, Japan.

The majority of murine Thy-1+ dendritic epidermal T cells (DETC) express virtually identical TCR encoded by V gamma 5 and V delta 1 genes and are derived from early fetal thymic precursors. However, not consistent with this notion is an early finding that DETC arise continuously from bone marrow (BM) precursors by a thymus-independent mechanism. To address this issue, donor-type DETC were characterized in lethally irradiated mice that were reconstituted by Thy-1-disparate BM cells with or without a thymus. The BM-derived DETC, unlike their normal TCR-gamma delta counterparts, were found to express the TCR- alpha beta/CD3 complex and CD8, and their migration to the epidermis dermis occurred independently of the thymus. The numbers of the BM- derived DETC increased with time and reached a plateau 6 mo after BM transfer, at which time the TCR-alpha beta/CD3 complex was expressed on a small fraction of the DETC in athymic BM chimeras. Although no further increase in the number was observed at later times, at 1 yr after transfer most of the BM-derived DETC came to express the TCR- alpha beta/CD3 complex in the absence of thymic influence. By contrast, most of BM-derived T cells in other lymphoid organs from athymic BM chimeras still failed to express the TCR-alpha beta/CD3 complex even at 1 yr after transfer. These results suggest that extrathymic differentiation of BM-derived DETC could occur with the epidermal microenvironment.