Identification of an equivalent to murine Thy-1+ dendritic epidermal cells in the rat epidermis

Phenotypic diversity of antigen-presenting cells in ovine-afferent intestinal lymph

The phenotypic and functional repertoire of antigen-presenting cells (APCs) remains incompletely characterized, particularly during the migratory phase of their life history, when these cells leave peripheral tissues and travel via afferent lymphatic vessels to regional lymph nodes. Lymphatic cannulation procedures were used to collect ovine APCs as they migrated from the mucosa of the small intestine to regional lymph nodes. A panel of 19 new monoclonal antibodies (mAbs) was produced to characterize surface molecules expressed on APCs by means of two-color flow cytometry and microscopy. Two broad patterns of mAb reactivity were evident. Twelve mAbs reacted almost exclusively with cells in the APC-gated region, because all these mAbs stained < 3% of cells in the lymphocyte-gated region. Within this group, some mAbs identified distinct subsets of dendritic cells (DCs). The second group of seven mAbs displayed high-intensity staining on cells in the APC-gated region but also reacted with variable numbers (4-26%) of cells in the lymphocyte-gated region. This indicates that molecules recognized by these mAbs are highly expressed on APCs but also occur on other lineages. When new mAbs were analyzed by two-color flow cytometry of cells in afferent intestinal lymph, a wide range of differences in reactivity were observed, especially on CD11b(+), CD11c(+), CD4(+), MHCII(+), and gammasigmaTCR(+) cells. Although molecular specificities of mAbs reported here remain undefined, marked heterogeneity of staining patterns indicates considerable phenotypic, and probably functional, diversity within APC population in afferent intestinal lymph. MAbs reported here will provide useful tools to explore these features further.

The role of dendritic cells in cutaneous immunity

This article reviews the role of dendritic cells in cutaneous immunity. Langerhans cells (LC) found in the epidermis are the best-characterized dendritic cell population. They have the ability to process antigen in the periphery, transport it to the draining lymph nodes (DLN) where they are able to cluster with, and activate, antigen-specific naive T cells. During migration LC undergo phenotypic and functional changes which enable them to perform this function. There are other less well-characterized dendritic cells including dendritic epidermal T cells, dermal dendrocytes and dermal "LC-like' cells. Although there is no evidence that dendritic epidermal T cells (DETC) can present antigen or migrate to lymph nodes, they do influence the intensity of cutaneous immune responses to chemical haptens. Antigen-presenting cells (APC) in the dermis may provide alternative routes of antigen presentation which could be important in the regulation of skin immune responses. Therefore, dendritic cells are vital for the induction of immune responses to antigens encountered via the skin. LC are particularly important in primary immune responses due to their ability to activate naive T cells. The faster kinetics of secondary responses, and the ability of nonprofessional APC to induce effector function in previously activated cells, suggest that antigen presentation in the DLN may be less important in responses to previously encountered antigens. In these secondary responses, dendritic and nondendritic APC in the skin may directly induce effector functions from antigen-specific recirculating cells.

T cell receptor expression by dendritic epidermal T cells

Dendritic epidermal T cells (DETC) in murine epidermis express the gamma delta T cell receptor (TCR). The major population of DETC utilize V gamma 5 and V delta 1 without any junctional diversity, corresponding to the earliest fetal thymocytes which express TCR gamma delta. Using PCR, we recently found another population of DETC which express V gamma 1-V delta 6 with junctional diversity in addition to V gamma 5-V delta 1, although they exist in small numbers in normal mice. In athymic nude mice, V gamma 1+ cells also exist. Therefore, this subset of gamma delta T cells is the product of an extrathymic pathway. These V gamma 1+ cells may recognize mycobacterium antigen or heat shock protein (HSP), thus playing an important role in the first defense of the skin. In contrast to normal mice, in nude mice, we could not detect any DETC using anti CD3 epsilon antibody (2C11). In order to solve this puzzle, we examined the components of TCR complex utilizing immunoprecipitation and northern blot analysis. TCR is composed of either alpha beta or gamma delta chains associated with CD3 gamma, delta, epsilon and zeta-zeta chains. By immunoprecipitation of 125I labelled DETC cell lines using anti-CD3 epsilon antibody, we detected gamma delta chains and CD3 gamma and CD3 epsilon chains, but not CD3 delta or CD3 zeta chains. Northern blot analysis showed that these cells express CD3 gamma, epsilon, and zeta chains, but not the CD3 delta chain.(ABSTRACT TRUNCATED AT 250 WORDS)

T-cell receptor diversity in dendritic epidermal T cells in the rat

The rat epidermis contains a population of dendritic CD3+ cells. For a better characterization of these cells and to investigate their relationship to epidermal lymphocytes of other species, we stained rat epidermal sheets using a variety of monoclonal antibodies against rat leukocyte differentiation antigens in an indirect immunofluorescence procedure. Additionally, we attempted to define their T-cell receptor (TCR) isotype at both the nucleic acid and protein level. Results obtained showed that the majority of the CD3+ dendritic epidermal cells are CD45+, CD2+, TCR alpha beta-, major histocompatibility complex class II-, Thy-1-, asialo GM1-, CD4-, CD5-, and CD8- lymphocytes. We further observed that, in contrast to the mouse system, the rat epidermis additionally harbors a small but distinctive portion of dendritic CD3+ cells that exhibit reactivity with an anti-pan TCR alpha beta monoclonal antibody. Our further finding that rat epidermal cells enriched for CD3+ lymphocytes express full-length C delta mRNA suggests that the vast majority of rat epidermal T cells carry surface-bound TCR gamma delta moieties. On the basis of these findings, one may speculate that the indigenous T-cell population of the epidermis is not necessarily programmed to uniformly express monomorphic TCR gamma delta molecules but, to effectively fulfill its role in host defense, is capable of adaptation to the specific challenges encountered by a given species.