Growth and differentiation of human keratinocytes on extracellular matrix

Extracellular matrices (ECM) have been reported to enhance epithelial cell attachment and proliferation as well as to induce differentiation in vitro. Since ECM components are physiological constituents of the dermoepidermal basement membrane, we studied the growth and differentiation of human keratinocytes on ECM in order to determine the benefits of culturing epidermal epithelial cells (keratinocytes) on reconstituted basement membranes. Disaggregated epidermal cells were grown in primary and subcultures in liquid medium; the attachment of the cells was greatly enhanced by ECM and noted within the first few hours after seeding; cells formed small islets that reached confluence within 2-12 days depending upon the plating density and the type of culture (primary or passages). Histological and ultrastructural cross-sections of the cultures clearly indicated that a multilayered epithelium can be obtained including a basal cell layer, several intermediate cell layers with cytoplasmic organelles, intermediate size filaments, desmosomes, and keratohyaline granules, and an upper layer of anucleated cells. Using immunofluorescence, both pemphigus and pemphigoid (basal membrane zone) antigens were expressed. The keratin pattern noted indicated that these epithelia differentiate and keratinize but do not express a complete program of keratinization, a finding usually noted when cells are grown submersed. These data show that ECM favor epidermal cell proliferation and differentiation and suggest that they may be used to obtain large amounts of epidermal equivalent suitable for grafting and/or in vitro studies.

Functional effects of epidermal cell culture supernatants (ECCS) on human B-cell activation

Epidermal cells (EC) were cultured without stimulation and the effect of these EC culture supernatants (ECCS) on human in vitro B-cell response was determined. Supernatants obtained between Days 5 and 7 were able to replace monocytes in the antibody response to the particulate antigen trinitrophenyl-polyacrylamide (TNP-PAA). These results were obtained when highly monocyte-depleted cultures (less than 0.5% peroxidase-positive cells) were used and were reproduced with supernatants from several different EC cultures. ECCS could not substitute for T cells in the T-dependent response to TNP-PAA. They contained an interleukin 1 (IL-1) activity but no interleukin 2 or B-cell growth factor (BCGF) activities. We tested the effect of ECCS on the proliferative response of highly monocyte-depleted B cells cultured at low cell density costimulated with anti-u antibody and BCGF. ECCS had no BCGF-like activity of its own but did potentiate the effect of BCGF. Thus EC cultures produce IL-1-like factor(s) which act directly on the early stages of B-cell activation.

Growth and differentiation of human epidermal cultures used as auto- and allografts in humans

Human keratinocytes from small skin specimens were grown on mouse 3T3 cell feeder layers into epidermal sheets free from Langerhans cells and MHC class II antigen. These were found to be suitable for the permanent coverage of wounds when used as autografts or allografts. We report here the ultrastructural differentiation of this cultured epidermis after grafting onto autologous or allogeneic recipients. The cultured epidermis was a thin but multilayered Malpighian epithelium composed of keratinocytes at different stages of differentiation. The dermo-epidermal basement membrane was newly synthesized during the first few days following transplantation onto de-epidermized wounds. The analysis of keratins and examination of various keratinocyte membrane antigens by immunofluorescence indicated that full terminal epithelial differentiation was only achieved after in vivo transplantation of the cultured epidermis. Langerhans cells, absent in cultures, progressively colonized the grafts, while melanocytes, not detectable in sections of the cultures, were identified among the keratinocytes 2 weeks after grafting.

Expression of class I-MHC antigens by cultured human epidermis and epidermal allografts

In vitro grown class II-MHC antigen free epidermal sheets were used as epidermal allografts (EAG) across a major histocompatibility barrier in 20 non-immunosuppressed recipients suffering from leg ulcers. Class I antigens were expressed on cell membranes of basal cell layer only on the epidermal sheets. After grafting, patchy areas of membrane fluorescence were observed among cells from the suprabasal layers on the epidermis from skin biopsies taken between days 5 and 28. All cells of the basal and the suprabasal layers expressed class I antigens on biopsies taken after day 28, as on normal human epidermis. This work demonstrates that class I antigens are expressed by epidermal cells in cultures used for grafting. The absence of rejection cannot be explained by the absence of class I-MHC antigens in EAG.

Epidermal cell-derived lymphocyte differentiating factor (ELDIF) inhibits in vitro lymphoproliferative responses and interleukin 2 production

We have examined the biologic characteristics and immunologic properties of epidermal cell-derived lymphocyte differentiating factor (ELDIF), a lymphocyte differentiating factor produced by cultured human keratinocytes. The ELDIF was semipurified by a gel filtration procedure. This factor, which is distinct from prostaglandins, epidermal cell-derived thymocyte activating factor (ETAF), and the well-known thymic hormones (thymulin, thymopoietin, and thymosin alpha 1) did not exhibit any interleukin (IL)-1, IL-2, or IL-3 activity. It strongly inhibited in vitro lymphoproliferative responses of normal mouse spleen cells to phytohemagglutinin, concanavalin A, and lipopolysaccharide. This dose-dependent phenomenon was associated with a suppression of IL-2 production rather than any toxic effect. It can be concluded that ELDIF, a product of human epidermal cells, which displays in vitro T-cell differentiation and regulatory activities, could be of major importance in vivo in the control of cutaneous inflammatory reactions.

Progressive replacement of human cultured epithelial allografts by recipient cells as evidenced by HLA class I antigens expression

Human keratinocytes may be grown in vitro into living epithelia devoid of Langerhans cells and MHC class II antigens. These epithelia have been shown to be usable as epidermal allografts in patients with dermal wounds, without any apparent sign of rejection in the 12-month follow-up study. To evidence a progressive replacement by recipient cells of the grafted keratinocytes, we employed anti-MHC class I antigen monoclonal antibodies directed against tissue specificities expressed by either donors or recipients. At 2 and 4 weeks after grafting, some small epithelial cell islets from the recipient phenotype were clearly identified among cells from a donor origin by indirect immunofluorescence. At 6 months, all keratinocytes present at the grafted areas were labelled by antibodies directed toward recipient specificities only. This replacement may be related to the fact that, when placed on such superficial dermal wounds, the allografts are likely colonized by epithelial cells proliferating from residual recipient dermal appendages.

Long-term survival and immunological tolerance of human epidermal allografts produced in culture

Human epidermal cells from a small skin specimen can be grown in culture into multilayered sheets suitable for the permanent coverage of large burn wounds when used as epidermal autografts. We report here on the long-term survival of such cultured epidermal sheets used as epidermal allografts (EAG) across a major histocompatibility barrier in three nonimmunosuppressed adult patients, suffering from large chronic grafted leg ulcers, where the EAG have been placed to cover the conventional split-thickness skin autograft donor site. The absence of rejection was based upon clinical, histological, and immunopathological observation of the allografted sites at various intervals after grafting of the EAG. The identity of the epidermal cells on the grafted area with cultured cells from allogeneic donor was then established after blood substance typing by indirect immunofluorescence. Furthermore, epidermal cells from cultured sheets, but not control human cells from freshly excised normal epidermis, failed to stimulate the recipient peripheral blood cells in the mixed epidermal cell lymphocyte culture reaction, a finding that is related to the complete absence of class-II-antigen-bearing cells in cultured epidermis. This absence of T cell stimulation was noted not only on the day of grafting but throughout the follow-up. Altogether, these findings show that Langerhans cell and other class-II-antigen-bearing cell-depleted cultured epidermal allografts, are tolerated in unrelated recipients. EAG may serve as a skin substitute in patients with large wounds or burns. Since EAG may be grown continuously, the coverage of burns may not then be limited by the availability of the donor site, or by the time necessary to produce epidermal tissue in cultures.

Effects of external potassium concentrations on the cell sodium and potassium contents of isolated rat kidney tubules

The effects of 20 mumol/l amiloride, 10 mumol/l furosemide and 1 mmol/l ouabain on cell Na and K concentrations were investigated by flame microphotometry in isolated rat medullary collecting tubules and medullary thick ascending limbs (MCT and MAL) as a function of the external potassium concentration [Ke]. The results are expressed as Na and K concentrations per liter cell volume ([Nac] and [Kc], mmol/l) and relative sodium content, [Nac]/([Nac] + [Kc]). From the experimental curves, [Ke]1/2 is defined as the [Ke] value corresponding to half maximal exchange of K against Na in cells. When [Ke] was 5 mmol/l, the relative Na content was less than 15% in control and amiloride-treated MCT as well as in control and furosemide-treated MAL, and about 24% in ouabain-treated MCT and MAL. In MCT, relative cell Na content increased up to 90% or more when [Ke] was reduced from 2.5 to 0.25 mmol/l. [Ke]1/2 was 0.55, 0.45 and 1.25 mmol/l for control, amiloride-treated and ouabain-treated MCT respectively. In MAL, similar increases in relative Na content were observed when [Ke] was reduced from 0.5 to 0.05 mmol/l. [Ke]1/2 was 0.25, 0.10 and 1.75 mmol/l for control, furosemide-treated and ouabain-treated MAL respectively. When [Ke] was reduced from 5 to 1 mmol/l, [Nac] dropped from 16.4 to 8.4 mmol/l (P less than 0.01) in control MAL. When [Ke] was 5 mmol/l, [Nac] was lower in furosemide-treated MAL (7.8 mmol/l) than control MAL (P less than 0.01). At 1 mmol/l [Ke], [Nac] was similar in both groups. These results are discussed in terms of the balance between the active and passive components of Na and K fluxes across apical and basolateral cell membranes. They indicate that a K-dependent passive Na entry process exists in the membranes of MAL cells but not of MCT cells. This process was proportionally more inhibited than the active Na pump when [Ke] was reduced from 5 to 1 mmol/l. In addition, it was found sensitive to furosemide.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of allogeneic T-cell activating ability and Langerhans cell markers in human epidermal cell cultures

Human Langerhans cells are the only epidermal cells that express the T6 and HLA-DR antigens and are responsible for the in vitro allogeneic T-cell proliferative responses in the mixed skin cell lymphocyte reaction (MSLR). To investigate the presence of Langerhans cells in normal human epidermal cell cultures, epidermal cell suspensions obtained from normal human skin specimens and from the subsequent epidermal cell cultures were analyzed by indirect immunofluorescence for the presence of T6 and HLA-DR determinants. In parallel, MSLRs were conducted with suspensions of cultured epidermal cells as stimulatory cells. These studies present evidence that when human epidermal cells are grown in culture, they loose both the ability to stimulate the proliferation of allogeneic T lymphocytes in vitro and their expression of HLA-DR and T6 antigens. The T6 antigens were lost during the first 2 weeks of culture, while HLA-DR determinants were still expressed by a small number of cells and were progressively lost through duration of cultures. The loss of HLA-DR antigens closely paralleled the progressive inability of human epidermal cells in culture to stimulate allogenic T cells in MSLR.

Effects of temperature, ouabain and diuretics on the cell sodium and potassium contents of isolated rat kidney tubules

Cell Na+ and K+ contents were measured by flame photometry in single pieces of rat medullary thick ascending limb (MAL) and medullary collecting tubules (MCT) after an overnight incubation at various temperatures. Below 8 degrees C, MCT samples were no more able to sustain high-K+, low-Na+ cell concentrations, and sodium progressively replaced cell potassium as the temperature decreased. The loss of potassium and the accompanying accumulation of sodium by MCT cells occurred at lower or higher temperature when amiloride (20 mumol/l) or ouabain (1 mmol/l) was present respectively in the incubation medium compared to that observed on control non-treated MCT. In contrast, MAL samples maintained normal cation gradients across their membrane at all temperatures, including 0 degree C, even in the presence of ouabain. However, MAL cells lost nearly all their potassium which was replaced by sodium when they were incubated in K+-free solution. These Na+-loaded, K+-depleted MAL cells restored high-K+ and low-Na+ contents similar to those of control samples when they were further incubated for 1 h at 0 degree C in presence of 5 mmol/l external potassium. Even in the presence of 1 mmol/l ouabain and at 0 degree C, a restoration of almost normal cation gradients occurred provided that Na+-loaded MAL were incubated for 24 h after potassium addition to the external medium. The results are discussed in relation to the respective effects of low temperatures on the passive and active components of the cation balance in the cells of the two nephron segments.

Ultrastructure of multilayered cultures of human gingival epithelial cells: attachment to enamel surfaces in vitro

Human gingival cells were collected using an enzymatic procedure and seeded on a feeder layer of irradiated mouse 3T3 fibroblasts. Epithelial cells generate stratified colonies ultimately forming an epithelium which was studied using electron microscopy. When this epithelium-like structure was dispased and transferred to enamel surfaces, the relationship between basal cells and enamel corresponded to half-desmosomes and a discontinuous extracellular matrix.

Recent advances of ultrastructural immunocytochemistry of epidermal Langerhans cells

Using electron microscopy, the immunological visualization of the membrane antigens of Langerhans cells (LC) can be performed by immunoperoxidase and immunogold techniques. The immunoperoxidase labelling permits the identification of only one antigen and the observation of qualitative variations of surface antigens. The immunogold method allows the identification of one antigen or simultaneously two or three surface antigens using gold particles of various sizes. This technique can be used to quantify the surface density of antigens on the cell membrane. The simultaneous identification of different surface antigens can be correlated with the ultrastructural characteristics of the cells. Using this technique we have recently demonstrated the existence of LC subsets in normal epidermis, and the presence of circulating T6-positive cells in normal subjects. In addition, a very low density of T4 antigenic sites on the LC membrane surface was observed. Several problems of a double-labelling immunogold technique related to steric hindrance and current artifacts are discussed.

Langerhans cell induced cytotoxic T-cell responses against normal human epidermal cell targets: in vitro studies

We investigated the role of class II MHC (HLA-DR Ia-like) antigen-bearing Langerhans cells in the in vitro generation of human alloreactive cytotoxic T lymphocytes (CTL) directed against epidermal cells (EC). Normal EC in suspensions (from reconstructive surgery specimens) and anti-DR monoclonal antibody plus complement (C')-treated EC were used to stimulate peripheral blood (PB) T cells (T cells allogeneic or autologous to EC) in a classical 6-day human mixed skin cell-lymphocyte culture reaction (MSLR). CTL responses were then tested in 51Cr release assays against cultured EC (EC grown on collagen-coated plates in parallel to MSLR). CTL responses to EC were observed only after allogeneic MSLR and when targets and EC used in MSLR were from the same donor. They were comparable in magnitude to those seen in parallel studies using PBL from the same donor as the stimulating EC as target cells. They were abolished when EC used in MSLR were depleted in class II MHC Langerhans cells (preincubation of EC suspensions with anti-DR + C'). These data show: (a) alloreactive CTL to human normal EC may be generated in MSLR, as previously shown in animals; (b) the MSLR is an in vitro model of primary immunization against EC; (c) Langerhans cells are necessary for the generation of cell-mediated cytotoxicity reactions occurring against epidermal cells.

[Pruritus vulvae]

Vulvogenital pruritus is due to infectious, dystrophic or dermatological causes. Diagnoses of "senile" or "psychogenic" pruritus do not obviate the need for regular surveillance. Treatment is easy if the cause is duly recognised. It is more difficult in essential forms and the authors describe the principles and methods of symptomatic treatment.

Immunogold technique applied to simultaneous identification of T6 and HLA-DR antigens on Langerhans cells by electron microscopy

A double-labeling immunogold technique in electron microscopy and specific monoclonal antibodies to surface antigens of Langerhans cells (OKT6 and BL2) were applied to assess directly the coexpression of two cell surface antigens (T6 and HLA-DR antigens) in a heterogeneous epidermal cell suspension. Electron microscopic examination of double-labeled cells revealed that all Birbeck granule-containing Langerhans cells bound OKT6 and BL2. The preparation of markers with colloidal gold particles and the procedure for double labeling are described. Several problems related to the steric hindrance and current artifacts are illustrated by micrographs and also discussed.

Human epidermal cell-induced generation of alloreactive cytotoxic T-lymphocyte responses against epidermal cells. Requirement for DR-positive Langerhans cells

Human epidermal cells act as stimulators in the mixed-skin cell lymphocyte culture reaction (MSLR). To analyse the generation in MSLR of alloreactive cytotoxic T lymphocytes (CTL) in cell-mediated cytolysis of human epidermal cells. a phenomenon suggested by various observations of skin inflammatory processes in vivo, 18-h 51Cr-release assays against epidermal cells cultivated on collagen-coated plates (epidermal cells autologous to the stimulator cells in MSLR) were conducted after allogenic human MSLR. To analyse the role of human Langerhans cells and related epidermal dendritic cells, which are the only cells expressing the DR-Ia-like (class II) antigens in normal epidermis and in suspensions of normal epidermal cells, MSLR and CTL assays were conducted with, as stimulator cells, suspensions of normal human epidermal cells as controls, and, in parallel, suspensions of epidermal cells after preincubation with anti-class II monoclonal antibody and complement. The generation of alloreactive CTL to epidermal cells occurred only after allogenic MSLR and when targets and stimulator cells were from the same donor; it was abolished when epidermal cell suspensions used in MSLR were depleted in HLA-DR-expressing cells. These findings demonstrate that an epidermal cell-induced generation of cell-mediated cytotoxicity to human epidermal cells may occur in vitro. Langerhans cells and other class II antigen-expressing epidermal cells (dendritic indeterminate cells) are necessary for an optimal in vitro sensitization in MSLR and the subsequent generation of alloreactive CTL towards epidermal cells in man.

Production of a lymphocyte differentiating factor (ELDIF) by cultured human epidermal cells

T lymphocyte maturation activity of supernatants from cultured human epidermal cells was investigated using a biological rosette assay based upon Thy 1 induction on T cell precursors. Between days 5 and 18 of keratinocyte cultures, supernatants exhibited Thy 1-inductive properties. Optimal activity was found between days 10 and 14 of culture, which correspond to the beginning of epidermal cell stratification. This activity was independent of the presence of prostaglandin E. Absorption experiments using monoclonal and polyclonal antibodies showed that ELDIF was different from other recognized thymic hormones (thymulin, thymopoietin, thymosin alpha 1), produced by thymic epithelial cells and known to induce T cell markers.

The semi-quantitative distribution of T4 and T6 surface antigens on human Langerhans cells

We have used indirect immunogold electron microscopy to compare the respective density of cell membrane determinants revealed by OKT6 and OKT4 monoclonal antibodies on normal human Langerhans cells (LC): 12.9 +/- 3.5 gold granules were noted per cell section on OKT4-positive LC whereas 236.8 +/- 23.5 granules were counted per cell section on OKT6-reactive cells. These results confirm that human LC react with OKT4 antibody and they demonstrate a marked quantitative difference on LC surface between the antigenic determinants recognized by OKT6 and OKT4 antibodies.

In vitro studies of epidermal antigen-presenting cells. The mixed skin lymphocyte reaction: an in vitro model for the generation of alloreactive cytotoxic T cells by human epidermal cells

Langerhans cells and indeterminate cells are the unique antigen-presenting epidermal cells participating in human lympho-epidermal interactions. They bear class II HLA-DR molecules, can substitute for macrophages in antigen presentation, induce a T-cell proliferative response to antigens and haptens in sensitized donors, and are necessary for alloantigen T-cell activation and generation of alloreactive cytotoxic T cells in vitro. Indirect immunofluorescence and immunogold electron microscopy on class II positive epidermal cell enriched suspensions (panning, FACS) indicated two populations of DR-positive epidermal cells: strongly DR-positive cells (25-30, 8% of positive epidermal cells) and faintly DR-positive cells, with a density of surface DR sites of respectively 5 X 10(5) and 1 X 10(5). Most Langerhans cells are among this second group while indeterminate cells are usually strongly DR-positive. OKT6-labelled cells were only typical Langerhans cells.

Quantitative evaluation of two distinct cell populations expressing HLA-DR antigens in normal human epidermis

HLA-DR antigens are expressed only by Langerhans cells (LC) and indeterminate cells (IC) in normal human epidermis. Indirect immunofluorescence and ultrastructural immunogold labelling were used to study the HLA-DR expression by means of two anti-DR monoclonal antibodies (MCA). Freshly dispersed DR-positive epidermal cells expressed different densities of DR antigens on their membrane surface. Approximately 25% of DR-positive cells were strongly labelled by anti-DR-MCA and 75% were weakly stained. After 18 h in complete culture medium before labelling no significant difference in these percentages was observed. The lymphoid-like LC-enriched cells obtained by Ficoll-Hypaque centrifugation also had two populations of DR-positive cells: strongly labelled cells (30.8%) and weakly labelled cells (69.2%). DR-positive cells may be divided into two types according to the density of DR sites on their cell membrane: (I) type DR+ shows weak surface labelling by gold particles (8.8 +/- 3.0 gold particles/micron) and has cytoplasmic Birbeck granules, identifying such cells as typical Langerhans cells; (2) type DR shows strong membrane immunogold labelling (38.9 +/- 4.6 gold particles/micron) and may or may not contain Birbeck granules. The gold particles bound to the cell membrane were used to quantify the number of HLA-DR sites expressed on each cell type: 1 X 10(5) sites on DR+ cells and 5 X 10(5) on DR cells.

[Generation of cytotoxic lymphocytes in lympho-epidermal mixed cultures in man]

The ability of human normal skin epidermal cells (EC) to induce the generation of alloreactive cytotoxic T lymphocytes (CTL) was investigated in vitro using the Mixed Skin Cell lymphocyte Reaction (MSLR) model. In human MSLR, EC stimulated the proliferation of allogeneic peripheral blood lymphocytes (L) as measured, after 6 days, by 3H-thymidine uptake. In parallel, the generation of alloreactive CTL was tested in 18 hr 51CR release assays against L targets (targets autologous to EC that stimulated in MSLR). Allogeneic, not autologous MSLR, lead to the generation of CTL; alloreactive CTL were not generated against targets allogeneic to stimulating EC; no CTL activity occurred without previous stimulation by EC. These data indicate that in vitro MSLR may provide an useful tool for the investigation of lympho-epidermal interactions in man and our understanding of lymphocytotoxicity mechanisms that occur in vivo in response and/or directed to epidermal constituents .

Role of HLA-DR bearing Langerhans and epidermal indeterminate cells in the in vitro generation of alloreactive cytotoxic T cells in man

Human epidermal cells (EC) act as stimulator cells in the mixed-skin cell lymphocyte culture reaction (MSLR). To analyze the role of human epidermal Langerhans cells (LC) and indeterminate cells (IC), which are the only cells expressing the DR-Ia-like antigens in normal epidermis, in the generation of alloreactive cytotoxic T lymphocytes (CTL) in cell-mediated cytolysis, 18-hr 51Cr-release assays against PBL targets (targets autologous to stimulator EC) were conducted after allogeneic human MSLR. MSLR and CTL assays were conducted with, as stimulator cells, suspensions of normal human EC as controls, and EC after: (1) preincubation with anti-HLA-DR or OKT6 (specific for LC in EC suspension) monoclonal antibodies; (2) panning, a monolayer technique used to deplete EC suspensions in OKT6 or DR-positive cells. The generation of alloreactive CTL was found to occur only after allogeneic MSLR and when targets and stimulator cells were from the same donor; it was reduced by EC incubation: cytotoxic activity 26.66 +/- 3.84 (controls); 8.8 +/- 3.6 and 7.7 +/- 3.7 (EC incubated with OKT6 or anti-DR, respectively); it was reduced or abolished when the EC used in MSLR were depleted in OKT6 or DR-positive cells by panning. These findings demonstrate that human LC and IC are necessary for an optimal in vitro sensitization in MSLR and the subsequent in vitro generation of alloreactive CTL in man.

Detection of OKT6-positive cells (without visible Birbeck granules) in normal peripheral blood

The specificity of a monoclonal antibody (OKT6) for peripheral blood mononuclear cells was examined by indirect immunofluorescence and ultrastructural immunogold labelling. Some rare peripheral blood mononuclear cells (approximately 1%) expressed T6 antigen on their membrane surface, as determined by light microscopy and cytofluorometry. Electron microscopic examination of immunogold-labelled cells revealed that OKT6-positive cells were dendritic, lacking the Birbeck granules and expressed variable density of the membrane T6 antigen. The relationship of such cells with Langerhans' cells is discussed.

Ultrastructural immunogold labelling of human Langerhans cells enriched epidermal cell suspension

Colloidal gold particles are well suited as markers in electron microscopy. Indirect immunogold staining was used to identify cell membrane antigens defined by monoclonal antibodies OKT6 and BL6 on human Langerhans cells (LC) in suspensions. Isolated epidermal cells were obtained by skin trypsinization and enriched or depleted in OKT6 positive on BL6 positive LC using the panning method: incubation of OKT6 or BL6 preincubated cells on immunoglobulin coated dishes. Indirect immunogold staining was then performed after prefixation in 2% paraformaldehyde. In LC enriched suspensions, only LC exhibited a specific membrane labelling with OKT6 or BL6 recognized by the presence of small evently distributed gold granules. Neither Birbeck granules, nor other cytoplasmic organelles, were labelled. No other epidermal cells were found positive. In LC depleted suspensions, no labelling was observed. Immunogold labelling on LC enriched suspensions after panning is now in progress for the qualitative evaluation and the quantitative analysis of cell surface constituents and antigens expressed by human dendritic epidermal cells.

Simultaneous detection of T6 and HLA-DR antigens distinguishes three cell subpopulations in dispersed normal human epidermal cells

Normal human dendritic epidermal cells (EC) show specific surface membrane markers (T6 and DR antigens). This study presents evidence that, in dispersed EC suspensions, these membrane antigens may distinguish three antigen-positive EC subsets by means of double immunofluorescence labelling: 97.3 +/- 1.2% of the labelled cells were DR(+)/T6(+) while 2.2 +/- 0.9% were DR(+)/T6(-) and 0.5 +/- 0.6% were DR(-)/T6(+). Immunoelectron microscopy with gold particles confirms the co-existence of T6-positive and T6-negative epidermal cells.

Langerhans cells in skin from patients with psoriasis: quantitative and qualitative study of T6 and HLA-DR antigen-expressing cells and changes with aromatic retinoid administration

Using a monoclonal antibody against human HLA-DR antigens and OKT6, we investigated by indirect immunofluorescence the distribution of Langerhans cells in normal human skin and involved and uninvolved skin from patients with psoriasis before, during, and after systemic aromatic retinoid administration. In parallel, enumeration of HLA-DR and of OKT6+ cells was also performed. In involved psoriatic epidermis the distribution of positive cells was disturbed; OKT6+ cells were reduced in number, as were HLA-DR+ cells which were seen in clusters. In control skin sections, a regular pattern of fluorescent dendritic epidermal cells was noted. In normal-appearing human skin, in nonlesional psoriatic skin, but not in diseased psoriatic skin, the number of OKT6+ cells per epidermal section surface unit was higher than that of HLA-DR expressing cells. Changes in the number and distribution of OKT6 and HLA-DR+ cells in psoriatic involved epidermis were corrected by oral retinoid treatment.

Therapeutic use of TP5 (thymopoietin 32-36) in sarcoidosis of the skin

TP5, a synthetic pentapeptide corresponding to thymopoietin 32-36, was administered alone to eight adult volunteer patients with sarcoidosis. A dose of 50 mg of TP5 was given iv, three times a week for 6 weeks, to three patients with erythema nodosum (EN) and bilateral hilar adenopathy, and to one patient with sarcoids of the skin; and for 12 weeks, to the other four patients with skin sarcoids. Before treatment and every 3 weeks thereafter clinical features; routine laboratory tests; tests for cellular immunity, humoral immunity, and auto immunity; IgE levels; and polymorphonuclear functions were recorded. EN disappeared in 3 weeks; hilar adenopathy improved or disappeared more slowly. Improvement of skin sarcoids was noted (lesions flattened or were cured). No side effects were observed. No evident changes in routine tests, humoral and auto immunity, IgE levels, and functions of polymorphonuclear leukocytes were observed. Cutaneous anergy to skin multi-tests was observed in seven patients before treatment, and was corrected with TP5 in six cases. In patients with low levels of peripheral blood T cells and suppressor T cells (as determined using specific monoclonal antibodies), a progressive normalization was obtained with TP5. These data support the efficacy of TP5 in sarcoidosis, although the action of the drug may be only temporary, as spontaneous remission may have occurred in this open trial of only eight cases.

Immunohistochemistry in cutaneous pathology

Since the first demonstration of skin antibodies in sera of pemphigus patients by IF (Beutner & Jordon 1964), the scope of skin diseases in which immunologic findings may be of interest has enormously enlarged and dermatology remains one of the leading clinical specialities applying IHC in both diagnosis and research. Immunohistological techniques and, to a lesser degree, immunocytological techniques, have been developed to include not only IF, but also immunoenzymatic methods. Even if not all immunological findings may be disease specific and diagnostic, immunohistological techniques have become a very useful tool for studying skin biopsies in connection with serological methods. Their importance could be increased with rapid development of a new field: the study of normal skin constituents; e.g. Ag, collagen, keratin, with the help of specific polyclonal and monoclonal antibodies.

Vasopressin and angiotensin II receptors in rat aortic smooth muscle cells in culture

Rat aortic smooth muscle cells were isolated and maintained in primary culture. After 2-3 days, cells recovered their contractile phenotype and could be induced to contract in response to vasopressin and angiotensin II. Vasopressin- and angiotensin-specific binding sites were detected on these cells, using tritiated Lys8-vasopressin, Asn1-Val5-angiotensin II, and Sarc1-Ile8-angiotensin II. Vasopressin binding sites had Kd values of 30 and 12 nM for Lys8-and Arg8-vasopressin, respectively, and a maximal binding capacity of 25,000 sites/cell. They displayed several of the expected characteristics of vasopressin receptors involved in the vasopressor response in vivo. A highly significant correlation was found between the relative agonistic or antagonistic vasopressor potencies of a series of vasopressin structural analogues and their relative abilities to inhibit [3H]vasopressin binding to aortic smooth muscle cells. Specific binding sites for Asn1-Val5-angiotensin II and Sarc1-Ile8-angiotensin II had the following characteristics: Kd = 2.3 and 1.3 nM, respectively; maximal capacity: 50,000 sites/cell. Vasopressin and angiotensin did not modify the intracellular cyclic AMP content of aortic smooth muscle cells.

In vitro mixed skin cell lymphocyte culture reaction (MSLR) in man: analysis of the epidermal cell and T cell subpopulations

The nature of normal human epidermal cells (EC) and peripheral blood (PB) cells that react in vitro in allogeneic mixed skin cell lymphocyte culture reaction (MSLR) was investigated using monoclonal antibodies (MCAB) specific for cell subpopulations. T cells and helper-inducer and suppressor-cytotoxic T cell subsets were defined by OKT3, OKT4, OKT8 MCAB, respectively, whereas, among EC, Langerhans cells were characterized by reactivity with OKT6 or anti-HLA-DR MCAB. MSLR were conducted with untreated cell suspensions as controls and cells suspensions depleted of various functionally active cell subset(s). Two approaches were used for cell depletion: (1) complement (C')-mediated lysis by MCAB of T cells, T cell subsets, HLA-DR or OKT6 positive cells; (2) panning of PB cells or EC after pre-incubation with the appropriate MCAB to deplete or enrich (OKT6) cell suspensions with the respective cell subset. Responses in MSLR were abolished after treatment of PB cells with OKT3 + C' or OKT4 + C', significantly reduced with OKT8 + C'; they were abolished after incubation of EC with anti-HLA-DR + C' and significantly reduced with OKT6 + C'. After panning, OKT3 and OKT4 depleted populations did not proliferate in MSLR while OKT8 depleted populations respond as controls. OKT6 depleted EC were not able to stimulate PB cells, yet proliferation rates were increased after stimulation by OKT6 enriched EC. Data show that helper-inducer T cells (OKT3+; OKT4+) play the major role in MSLR and that the presence of Langerhans cells is necessary for the stimulation of PB cells. They also suggest that co-operation between helper and suppressor cells is necessary for an optimal response. Differences in results using either OKT6 or anti-HLA-Dr-C'-mediated treatment of EC may be related to differences in the cellular expression of these markers by EC.

[Autologous and allogeneic mixed lymphocyte-epidermal cell cultures in man. In vitro approach to lymphoepidermal interactions]

The ability of human normal skin epidermal cells (EC) to induce the proliferation of allogeneic and autologous lymphocytes was investigated in vitro in mixed skin cell-lymphocyte culture reaction (MSLR) as an in vitro approach of the lympho-epidermal interactions that are suspected to be involved in the pathogenesis of cutaneous inflammatory skin diseases and T cell lymphomas in man. Normal human EC were able to stimulate either allogeneic or autologous lymphocytes in MSLR in culture conditions similar to that previously reported in animals. The stimulation was higher in allogeneic than in autologous MSLR. MSLR did not appear to be affected by the trypsin treatment used to obtain EC in suspensions. Lymphocytes proliferation was maximal with a lymphocytes/EC ratio of 1:1. This suggests that autologous and allogeneic MSLR in man depends upon in vitro conditions similar to that studied in animals, and that MSLR may provide an useful tool for the study and the understanding of lympho-epidermal interactions in man.

Lectins as markers of human epidermal cell differentiation

The expression of sugar residues on human epidermal cells was investigated by means of lectin binding, as a way of determining membrane structural changes occurring during the differentiation of the epidermis. Fourteen lectins of different sugar specificity were conjugated with fluorescein isothiocyanate (FITC-lectins) and tested in fluorescence microscopy on frozen sections of normal human epidermis. In parallel, FITC-lectins were tested on psoriatic-involved epidermis to visualize differences in the expression of sugar residues that might occur during abnormal epidermal differentiation. No labelling could be obtained with lectins from Bandeira simplicifolia I, Dolichos biflorus, Limulus poyphemus, Tetragonolobus purpureas, Ulex europeus I, and Triticum vulgaris (group 1 lectins). A "pemphigus-like" intercellular labelling of the whole epidermis, except the stratum corneum, was obtained with lectins from Canavalia ensiformis. Maclura pomifera, Phaseolus vulgaris, and Ricinus communis I (group 2 lectins). A selective intercellular labelling of the stratum spinosum and the stratum granulosum was seen in normal epidermis with lectins from Arachis hypogaea, Glycine max, Helix pomatia, and Sophora japonica (group 3 lectins). In psoriatic epidermis, not only the basal cell layer, but also cells from the adjacent lower stratum spinosum were found to be negative, using FITC-lectins of group 3. These data indicate that the expression of lectin binding sites in normal epidermis differs according to the maturation of the cell from the basal cell to the more mature keratinocyte in the stratum granulosum. They suggest that lectins may be used as markers of epidermal cells in various stages of normal and abnormal differentiation.

Numeration of T cell subsets in sarcoidosis using monoclonal antibodies: decreased levels of peripheral blood T cells and cells with suppressor T cell phenotype

Peripheral blood lymphocytes frm 16 patients with sarcoidosis (9 patients with skin sarcoids, 7 patients with erythema nodosum and bilateral hilar adenopathy) and cutaneous anergy and from 23 age-matched healthy controls were characterized by reactivity with monoclonal antibodies OKT3, OKT4, OKT8 directed to surface antigens of T lymphocytes, helper-inducer and suppressor-cytotoxic T cell subsets, respectively. In contrast to healthy controls, patients with sarcoidosis had reduced percentages of OKT3+, OKT4+ and OKT8+ cells and a major decrease in the OKT8+ (suppressor) subset. However, these changes were significant only in the group of patients with acute sarcoidosis (erythema nodosum). This abnormal T cell distribution correlates with the alterations in cell-mediated immunity previously observed and suggests the presence of a defective circulating suppressor T cell activity in acute sarcoidosis.

OKT8 human phenotype expressed by Papio papio monkey lymphocytes

The potential cross-reactivity between human and Papio papio monkey lymphocyte antigens was investigated using various monoclonal antibodies specific for human T cell subsets and HLA-DR antigens. Monkey circulating lymphocytes expressed the OKT8 antigen, specific for the suppressor/cytotoxic T cell population and the HTLA antigens. These reactivities were also detected on lymphoid cells in the thymus and lymph nodes of the Papio monkey.

Use of monoclonal antibodies specific for T cell subsets in cutaneous disorders: I. Quantitative analysis of peripheral blood lymphocytes

Peripheral blood mononuclear cells obtained from patients with various skin disorders were studied by indirect immunofluorescence using the monoclonal antibodies OKT3, OKT4, and OKT8 which react with human T cells (OKT3+ cells), helper-inducer (OKT4+) and suppressor-cytotoxic (OKT8+) T cell subsets, respectively. In parallel, the balance between peripheral blood helper and suppressor subsets was established by the determination of OKT4+/OKT8+ ratios (helper/suppressor ratios). In patients with the Sézary syndrome, but not in patients with mycosis fungoides or parapsoriasis "en plaques," highly significant increases in the helper/suppressor ratios accompanied by decreased levels of suppressor cells were found compared to controls. T cell imbalance with high helper/suppressor ratios and low percentages of circulating OKT8+ suppressor cells were also observed in patients with atopic dermatitis, lichen planus, or acute sarcoidosis (i.e. patients with erythema nodosum sarcoidosis and bilateral hilar adenopathy). In patients with cutaneous manifestations of chronic graft vs. host diseases, low helper/suppressor ratios and elevated OKT8+ cell levels were observed. T cells and T cell subset enumerations and related helper/suppressor ratios were found to be within normal range in patients with psoriasis, systemic lupus, erythematosus, discoid lupus erythematosus, bullous disorders (bullous pemphigoid, dermatitis herpetiformis, pemphigus vulgaris), and miscellaneous diseases.

Intracellular keratins in normal and pathological bronchial mucosa. Immunocytochemical studies on biopsies and cell suspensions

The distribution of intracellular keratins was investigated in normal bronchial epithelium and in several morphologically distinct forms of respiratory tract carcinomas. This study was performed with two different experimentally produced antisera against normal human stratum corneum keratin and against keratin protein of MW 67,000 dalton, using indirect immunofluorescence and immunoperoxidase methods on tissue sections and cell suspensions. In normal bronchial epithelium, the basal cells were strongly labelled by both antisera. The ciliated columnar cells appeared devoid of cytokeratins in tissue sections but were strongly labelled with both antisera in cell suspensions. The goblet cells remained negative in every case. In squamous metaplasia of the bronchus, all epithelial cells were unevenly stained with both antisera. Among tumours, only the squamous cell carcinomas were strongly labelled by both antisera. Primary lung adenocarcinoma appeared weakly positive, whereas metastatic lung carcinomas, undifferentiated lung carcinomas, oat cell tumours, carcinoid tumours were negative. The immunocytochemical determination of keratins appeared to be of value in the study of normal and abnormal epithelial differentiation, in the diagnosis of poorly differentiated carcinomas and in their distinction from metastatic tumours of the lung.

[PMN leukocytes chemotaxis: inhibition by thalidomide (author's transl)]

The effects of thalidomide on chemotaxis of normal human peripheral blood PMN leukocytes have been studied in vitro. Chemotaxis factor was generated by interacting normal human serum with zymosan. At concentration of 1, 10 and 100 micrograms/ml, thalidomide failed to inhibit chemotactic factor. Pre-incubation of PMNs with thalidomide caused a marked, dose-independent inhibition of chemotaxis. Random mobility did not appear to be affected. Inhibition of PMN chemotactic ability by thalidomide may account for its ability to improve skin diseases such as aphtosis, discoid lupus erythematosus and other sun-sensitive and/or inflammatory dermatoses.

Pemphigus, pemphigoid, and epidermal upper-cytoplasmic antigens: changes in expression in cultured human keratinocytes

In an approach of epidermal differentiation, the expression of pemphigus, bullous pemphigoid, and upper-cytoplasmic epidermal antigens was studied in human keratinocytes in culture. The cells were cultured without feeder cells, dermal tissue, or collagen at an acid pH (5.6--5.8) similar to that of the surface of the skin in vivo. Cell suspensions from fresh trypsinized skin and primary, secondary, and tertiary cultures were tested by indirect immunofluorescence for the presence of each antigen using human sera from patients with pemphigus, bullous pemphigoid, and human sera with antibodies against upper-cytoplasmic antigens. Normal sera and cultured human normal fibroblasts and melanoma cells were used as controls. Pemphigus and pemphigoid antigens were found to be expressed, and synthesized by keratinocytes in vitro. The expression to upper-cytoplasmic antigens decreased with time in culture, and they were absent in secondary or tertiary cultures, while expressed by 45--65% of cells prepared from fresh skin. Both upper-cytoplasmic and pemphigoid antigens can be used to type subpopulations of human epidermal cells; however, these findings suggest that epidermal differentiation in vitro differs from that which occurs in vivo.

Decreased expression of epidermal cytoplasmic antigens in cultured human keratinocytes

The expression of upper cytoplasmic (U-CYT) antigens which are expressed only in the superficial layers of the epidermis and are markers of epidermal cell differentiation in vivo and of basement zone (BMZ) antigens reacting with bullous pemphigoid serum was studied in keratinocytes in tissue culture. The cells were cultured at an acid pH (5.6-5.8) similar to that of skin and without feeder cells, dermal tissue, or collagen. It was found that the expression of U-CYT antigens decreased markedly in culture. These antigens were expressed in 45-65% of epidermal cells prepared from fresh skin, but in only 5-10% of cells which had been grown in primary culture over 1 mo, and in no cells in secondary or tertiary culture. By contrast, BMZ antigens continued to be expressed in culture. These antigens were expressed by 20-35% of epidermal cells prepared from fresh tissue and by 15-35% of keratinocytes in primary, secondary or tertiary culture. These findings indicate that U-CYT and BMZ antigens can be used to type subpopulations of human keratinocytes in suspension, and suggest that the differentiation of these cells in vitro differs from that which occurs in vivo.