Search PubMed⌕ Search

Biomedical subjects

E Payer

Publications and source records attributed to E Payer.

10 recordsLinked to original sources
PubMed1995

Pathogenesis of post-thymectomy autoimmunity. Role of syngeneic MLR-reactive T cells.

Thymectomy of 3-day-old mice results in the development of multi-organ-specific autoimmune diseases. The disease process is mediated by CD4+ T cells and is characterized by an inflammatory infiltrate in the affected organ(s) and the presence of autoantibodies. Our analysis of the phenotype of the CD4+ T cells that remain in the 3-day thymectomized animal revealed that the majority (approximately 80%) of the CD4+ lymph node cells express an activated (MEL-14low) phenotype and a smaller percentage expressed the T cell activation Ag CD69 and IL-2R alpha-chain. Thymectomized animals also had an increase in the frequency of mitogen-induced CD4+ IL-4 producers and significantly higher levels of total serum IgG. Functional studies demonstrated that lymph node T cells from 3-day thymectomized mice had an enhanced response in the syngeneic MLR and appeared to preferentially respond to syngeneic dendritic cells. To determine whether the syngeneic MLR-reactive T cells were involved in the pathogenesis of the organ-specific disease, we developed a model that mimicked the 3dTx model by grafting neonatal thymi to adult nu/nu recipients followed by removal of the thymus graft on day 3 or 4. When compared with mice transplanted with an untreated thymus, nu/nu mice transplanted with adult APC-containing thymi demonstrated a decrease in the incidence and severity of gastritis, a marked decrease in the titer of anti-parietal cell Ab, and a decrease in total serum IgG. Thus, intrathymic tolerization to complexes of self-peptides and MHC class II on adult APC prevents organ-specific autoimmune disease.

Animals↗
PubMed1995

Phenotypic changes that TCR V gamma 3+ fetal thymocytes undergo during their maturation into dendritic epidermal T cells.

Murine Thy-1+, TCR V gamma 3/V delta 1+ dendritic epidermal T cells (DETC) express CD2 antigens, but differ from most other T-cell subsets in their absence of CD4, CD5, and CD8 antigens. To determine whether negativity for those antigens is an intrinsic feature of a given T-cell population or whether such triple-negative T cells go through a maturational stage during which they express these antigens, we determined the phenotype of TCR V gamma 3+ fetal thymocytes, which are the precursor cells of DETC. We found that TCR V gamma 3+ fetal thymocytes at day 17 of gestation are CD2+, CD5+, mostly CD8+, and partly CD4+. The expression of CD5 is highest on early TCR V gamma 3+ thymocytes; these cells express intermediate levels of CD5 when they leave the thymus and lose CD5 expression until or shortly after arrival in the epidermis. A similar loss of CD5 expression by TCR V gamma 3+ cells was observed in vitro under various culture conditions. To determine whether expression of CD5 is important for the maturation of DETC, we searched for these cells in the epidermis of CD5-deficient mice. There was no alteration in the number of Thy-1+/TCR V gamma 3+ dendritic cells in the epidermis of CD5-/- mice. Even though the latter finding speaks against a pivotal role of CD5 during the maturation of DETC, the described cell system may serve as a useful tool in further experiments aimed to clarify the function of the CD5 glycoprotein as well as the mechanism(s) regulating its expression.

Animals↗
PubMed1994

CD5- dendritic epidermal T cells are derived from CD5+ precursor cells.

Murine Thy-1+, TcR V gamma 3/V delta 1+ dendritic epidermal T cells (DETC) differ from most other T cell subsets by the absence of CD4 and CD8 antigens as well as the lack of CD5 expression. To see whether negativity for those antigens is an intrinsic feature of a given T cell population or if such triple-negative T cells go through a maturational stage where they express these antigens, we determined the phenotype of TcR V gamma 3+ fetal thymocytes which are the precursor cells of DETC. We found that TcR V gamma 3+ fetal thymocytes phenotypically differ from mature DETC in that they are CD5+, mostly CD8+ and partly CD4+. The injection of fetal thymic suspensions containing TcR V gamma 3+/CD5+ (but not TCR V gamma 3+/CD5-) thymocytes into Thy-1-disparate athymic nude mice resulted in the appearance of donor-type TcR V gamma 3+/CD5- dendritic cells in the recipients' epidermis, indicating that TcR V gamma 3+ thymocytes are indeed the precursors of CD5- DETC. Tracing CD5 expression on DETC precursors during their intrathymic maturation and their migration to the fetal skin, we found that (i) the earliest DETC precursor cells as defined by TcR V gamma 3 expression express high levels of CD5 antigen (day 15 of gestation), (ii) after day 16 of gestation 70% of TcR V gamma 3+ thymocytes express high and 30% express intermediate levels of CD5, (iii) TcR V gamma 3+ cells in the fetal blood express low levels of CD5, (iv) the first TcR V gamma 3+ cells entering the epidermis express very low levels of this antigen and (v) TcR V gamma 3+ epidermal cells later than day 19 of gestation are CD5-. A similar down-regulation of CD5 expression on DETC precursors was also noted when TcR V gamma 3+ cells were cultured in vitro. Even the addition of PMA and ionomycin, which up-regulates CD5 expression on TcR alpha/beta-bearing thymocytes and lymph node T cells, could not prevent CD5 down-regulation on DETC precursors. The described cell system may serve as a useful tool in further experiments aimed to clarify the function of the CD5 glycoprotein as well as the mechanism(s) regulating its expression.

Animals↗
PubMed1994

Expression of monoclonal antibody HECA-452-defined E-selectin ligands on Langerhans cells in normal and diseased skin.

The cutaneous lymphocyte-associated antigen recognized by the monoclonal antibody HECA-452 has been thought to play a major role in the homing of memory T-cell subsets to the skin by virtue of its ability to bind to E-selectin of dermal microvascular endothelial cells. Considering that the homing of different leukocyte populations to the skin may involve similar mechanisms, we studied the expression of HECA-452-reactive molecules on CD1a+ epidermal Langerhans cells. Immunofluorescence double-labeling of cryostat sections and epidermal sheets of normal skin revealed HECA-452 immunoreactivity on a subpopulation of dermal and epidermal CD1a+ cells, whereas upon flow-cytometric analysis of epidermal single cell suspensions virtually all CD1a+ cells bound HECA-452 antibodies. We observed a marked upregulation of HECA-452-antigen expression on CD1a+ epidermal cells and a pronounced increase in the number of HECA-452+/CD1a+ dermal cells in lesional skin from inflammatory and neoplastic lymphocytic skin diseases, compared to normal skin. The molecule detected by the HECA-452 antibody on Langerhans cells is neuraminidase sensitive and contains a CD15 (LewisX) carbohydrate backbone. Because Langerhans cells react with the sialyl-LewisX-specific antibody CSLEX1, it is very likely that the HECA-452-reactive structure is or contains sialyl-LewisX. Our data are compatible with the view that i) resident epidermal Langerhans cells upregulate HECA-452-antigen expression due to the cytokine profile generated in the disease process or ii) that Langerhans cell precursors express HECA-452-antigens and show an enhanced immigration into lesional skin. The characterization of HECA-452+ cells in peripheral blood may not only clarify this issue but may also help to identify the still elusive Langerhans cell-precursor.

Antibodies, Monoclonal↗
PubMed1993

In vivo cytokine expression in normal and perturbed murine skin--analysis by competitive quantitative polymerase chain reaction.

Although cells from both epidermis and dermis have been shown to produce a variety of soluble mediators in vitro, it is not clear whether this reflects the in vivo situation. To study in vivo cytokine expression, whole skin as well as dispase-separated epidermis and dermis from normal adult mice were prepared and snap-frozen immediately. RNA was then extracted and analyzed both by conventional and by competitive quantitative polymerase chain reaction. Molecular analysis showed that murine skin in vivo constitutively expresses several cytokine genes at moderate (e.g., interleukin-1 alpha) or low (e.g., interleukin-6 and granulocyte-macrophage colony-stimulating factor) abundance. A striking, rapid upregulation was observed for some of these cytokines in the process of tissue separation. Of interest, the epidermal and dermal compartments exhibited different induction patterns: interleukin-1 alpha, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor-alpha expression were detected preferentially in the epidermis, whereas upregulation of interleukin-6 was found to be most prominent in the dermis. This pattern of cytokine expression was also reflected in supernatants generated from the respective single-cell suspensions. Thus, this study determines the baseline in vivo cytokine expression in the skin and the occurrence of immediate, compartment-specific alterations on perturbation. These data should contribute to our understanding of both skin homeostasis and the host-defense mechanisms initiated following injury to this organ.

Amino Acid Sequence↗
PubMed1992

Cytokine pattern of Langerhans cells isolated from murine epidermal cell cultures.

In the present study we demonstrate that supernatants of highly enriched cultured Langerhans cells (cLC) display IL-1, IL-6, granulocyte/macrophage (GM)-CSF, and TNF-alpha, but no IL-2, IL-3, IL-4, and IFN-gamma activities. We further show that IL-6, GM-CSF, and TNF-alpha bioactivities can be specifically blocked in the presence of the respective neutralizing mAb. Concerning the IL-1 bioactivity, the combined use of anti-IL-1 alpha and anti-IL-1 beta mAb was needed to completely inhibit the proliferative response of the indicator cell line D10. One of the difficulties in studying the secretory potential of LC is that even highly enriched cLC are contaminated with keratinocytes (KC), which are known to be a rich source of cytokines. To overcome this problem we compared cytokine bioactivities in supernatants of cell cultures consisting of selected cLC:cKC ratios. These cell mixing experiments revealed that cLC are the major source of the IL-6 bioactivity, whereas IL-1, GM-CSF, and TNF-alpha are predominantly generated by cKC. In order to determine whether the cytokine bioactivities measured in supernatants of epidermal cell cultures are simply caused by an increased release or by de novo synthesis, we performed molecular biologic studies. Polymerase chain reaction analysis of cLC and cKC revealed that IL-1 beta and IL-6 transcripts are virtually limited to cLC, whereas IL-1 alpha, GM-CSF, and TNF-alpha messages are preferentially exhibited by cKC. mRNA coding for IL-2, IL-3, IL-4, and IFN-gamma could neither be amplified from cLC nor from cKC. Furthermore, the quantitative comparison of cytokine transcripts in cLC vs cKC using Northern blot analysis and mRNA detection on the single cell level using in situ hybridization confirmed that cLC generate IL-6, whereas cKC synthesize IL-1 alpha and GM-CSF. Taken together our results demonstrate that cultured murine LC synthesize and secrete IL-1 beta and IL-6, cytokines known to be important accessory molecules in T cell activation.

Animals↗
PubMed1992

Fetal skin: a site of dendritic epidermal T cell development.

Thy-1 Ag and CD3-associated TCR-gamma (V gamma 3)/delta (V delta 1) are coexpressed on virtually all dendritic epidermal T cells (DETC) in the adult mouse. In contrast, day 16 fetal mouse skin contains small numbers of CD45+/Thy-1+/CD3- but no CD3+ cells. To see whether the CD45+/Thy-1+/CD3- fetal skin cells can qualify as DETC precursors, we transplanted day 16 fetal skin of C57BL/6 (Thy-1.2) mice onto adult B6Pl-Thy-1a (Thy-1.1) animals. At certain time points after transplantation, grafts were analyzed for the presence of Thy-1 and CD3/TCR Ag. Examination of the grafts, 4 days after transplantation, revealed the presence of few donor-type Thy-1.2+/CD3- and some Thy-1.2+/CD3+ epidermal cells of either round or dendritic configuration. At 10 weeks after transplantation, essentially all CD45+/Thy-1.2+ epidermal cells were anti-TCR V gamma 3 and anti-CD3-reactive, displayed a uniformly dendritic configuration, and, thus, represent DETC. Our assumption that CD45+/Thy-1+/CD3- cells are the only lymphocytes within day 16 fetal skin gained additional support by the observations: 1) that unfractionated as well as anti-CD45 gated single cell suspensions prepared from day 16 fetal skin were consistently devoid of anti-CD3 epsilon and anti-TCR V gamma 3-reactive cells; and 2) that stimulation of these cell suspensions with either Con A plus IL-2 or IL-2 alone regularly resulted in the outgrowth of CD45+/Thy-1+/CD3-/TCR V gamma 3- cells, but never in the appearance of CD45+/Thy-1+/CD3+/TCR V gamma 3+ cells. Our additional finding that Con A plus IL-2- or IL-2-stimulated day 16 fetal skin cells and cell lines derived therefrom contain transcripts of some (CD3 gamma, TCR C beta, TCR C gamma 1, TCR C gamma 4) but not of other (CD3 delta, CD3 epsilon, TCR C alpha, TCR C delta) genes encoding the CD3/TCR complex suggests that Thy-1+/CD3- fetal murine skin cells are of T cell lineage. We therefore propose that the fetal skin microenvironment can provide the stimuli promoting growth and maturation of CD3/TCR V gamma 3/V delta 1-expressing DETC from their CD3- precursors.

Animals↗
PubMed1992

Demonstration of a CD3+ lymphocyte subset in the epidermis of athymic nude mice. Evidence for T cell receptor diversity.

The existence of CD3/TCR-bearing lymphocytes in athymic and thymectomized chimeric mice implies that T cell maturation can occur in the absence of a thymus. Considering the possibility that the epidermis may be one of the organs providing T cell educating stimuli, we attempted to characterize the Thy-1+ epidermal lymphocyte population of athymic mice. Immunohistologic studies of epidermal sheets revealed (1) that Thy-1+ epidermal cells of C57BL/6 nu/nu mice are CD5-, CD4-, and predominantly CD8-, and (2) that a minor subset of these cells displays anti-CD3 epsilon reactivity. Although these CD3+ epidermal cells could hardly be detected at 6 wk of age, they comprised approximately 2% of all Thy-1+ epidermal cells in 12-mo-old athymic mice. Most of these CD3+ cells expressed TCR-gamma/delta, but TCR-alpha/beta+ cells were also present. TCR-gamma/delta+ epidermal T cells of athymic mice preferentially expressed TCR V gamma 2, V gamma 4, and V gamma 5 specificities rather than TCR V gamma 3 as found on DETC of euthymic mice. Using mitogenic stimuli, we have succeeded in establishing cell lines and clones from BALB/c nu/nu and C57BL/6 nu/nu epidermis. Their marker profile corresponds to that seen on resident CD3+ epidermal cells, as well as on a very small subset of CD3+ splenic and lymph node lymphocytes of athymic mice. The ontogenetic relationship, if any, between the epidermal and lymphoid CD3+, CD5-, CD4-, CD8- cells, has yet to be clarified. Cell lines/clones representative of resident CD3+ epidermal cells of nu/nu mice should provide a useful tool in the elucidation of homing patterns and functional properties of extrathymically matured T cells.

Age Factors↗
PubMed1991

Circulating CD3+/T cell receptor V gamma 3+ fetal murine thymocytes home to the skin and give rise to proliferating dendritic epidermal T cells.

The presence of CD3/TCR V gamma 3 moieties on both dendritic epidermal T cells (DETC) and fetal murine thymocytes has led to the concept that fetal thymocytes expressing this particular TCR phenotype are the actual DETC precursors. To test this assumption, we injected i.v. thymocyte suspensions prepared from day 16 and day 19 fetal mice as well as from adult animals, into syngeneic and Thy-1-disparate nude mice, the epidermis of which contains only Thy-1+/CD3- lymphocytes. Phenotypic analysis of the recipient epidermis by in situ immunolabeling revealed that injection of day 16 and day 19 fetal, but not of adult, thymocytes resulted in the appearance of distinct clusters of DETC as judged by their dendritic morphology and uniform expression of CD3/TCR V gamma 3 receptors. The presence of CD3+/TCR V gamma 3+ cells in the fetal, but not in the adult, thymocyte population(s) together with the failure to detect DETC after transfer of Thy-1+/CD3- fetal thymocytes strongly suggest that CD3+/TCR V gamma 3+ thymocytes are the DETC precursors. Kinetic studies of the DETC population from 2 to 12 wk after cell transfer revealed a substantial increase in the cell density within the DETC clusters that was not accompanied by an increase in the number of clusters. Thus, it appears that newly arriving DETC undergo proliferative activity in situ. Collectively, our results show that, under the experimental conditions chosen, CD3+/TCR V gamma 3+ fetal thymocytes are actual DETC precursors. Although it is not clear whether these experimental conditions are representative of the in vivo situation, they may serve as a useful model for studying the mechanisms underlying the homing properties of different lymphocyte subsets.

Aging↗