Epidermal Cell Populations Research Articles

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.

Isolation and characterization of interferon-producing reticuloendothelial cells from mouse epidermis

A homogeneous population of trypsin-resistant epidermal cells has been isolated from newborn ICR mice. These cells are characterized by adherence, receptors for Fc-IgG, ATPase activity, phagocytosis of latex particles and opsonized sheep erythrocytes, and secretion of lysozyme and interferon. The production of interferon by these cells suggests that they may be important in protection against viral infections of the skin as well as in regulation of immune responses. The ultrastructure of these trypsin-resistant epidermal cells shows striking similarity to that of reticuloendothelial cells.

Perturbation of epidermal Langerhans cells in immunosuppressed human renal allograft recipients.

As an initial attempt to gain a better understanding of the basis for the increased incidence of ultraviolet-light-related skin cancer in chronically immunosuppressed human renal allograft recipients, we have compared both morphological and functional characteristics of epidermal Langerhans cell (LC) populations present in the forearm skin of nine such patients with those of age, sex, and race-matched controls. The LC surface densities in vacuum-induced blister-derived epidermal sheets taken simultaneously from extensor and flexor forearm skin of the patients were significantly lower than those observed in the controls. The most abnormal LC densities seen were in the patients' extensor forearm skin. Likewise there were disturbances in LC distribution and morphology that were most marked in the extensor forearm skin of patients. Differences in the alloantigen-presenting capacity of LCs present in epidermal cell suspensions prepared from patient and control forearm skin were also noted--however, these differences were not as great as were the LC density differences. The alloantigen-presenting capacity of patients' LCs was depressed proportionately more than was the alloantigen presenting capacity of their peripheral blood mononuclear cells. These results demonstrate that the LC population is clearly perturbed in human renal allograft recipients and that this perturbation is greatest in a sun-exposed region of skin.

The Langerhans Cell: An Overview and Update

AbstractThe Langerhans cell was discovered 116 years ago. During the past one and a half decades, after almost 100 years of little exploration, investigators have made remarkable advances in unfolding the morphologic and functional intricacies of this unique epidermal cell. At this time, it is known that the Langerhans cell is of mesenchymal origin and that it functions most significantly in antigen presentation. Its possible role in epidermal differentiation and keratinization has also been a subject of study and speculation. The Langerhans cell itself, as well as a unique set of surface markers, have been found to be subject to a varbty of external stimuli. Exposure of the skin to Langerhans cell depletors or factors which alter surface characteristics should be taken into account when evaluating patch and use test results. While intentional depletion of the epidermal Langerhans cell population may have therapeutic value in certain conditions such as allergic contact hypersensitivity, such manipulation ...

Proliferation-dependent effect of skin extracts (chalone) on mouse epidermal cell flux at the G1-S, S-G2 and G2-M transitions.

Epidermal cell proliferation in mice was studied from 4 to 11 h following a single intraperitoneal (IP) injection of a crude skin extract. Cell cycle flux parameters were evaluated by a combination of several methods. The G1-S and S-G2 transit rates were estimated by means of a 3(H)TdR double labelling technique, and the mitotic rate by use of colcemid. The 3(H)TdR labelling index was also measured. To examine the possible influence of the circadian rhythm, all experiments were performed at two different times of the day with high or low rate, respectively, of epidermal cell proliferation. All flux parameters were altered for the whole 7-h period. The relative inhibitory effect of the skin extract was related to the proliferative state of the epidermal cell population. Cell flux at the G1-S transition showed only minor circadian variations, and treatment with skin extract was followed by a relative reduction of cell flux at this transition that was similar at the two times of the day investigated. In contrast, cell flux at the S-G2 transition showed pronounced circadian variations. The effect of the skin extract on cells at this transition was different at the two times in the 24-h period. In general, inhibition expressed as percent of the controls was stronger when the skin extract was given at times when the cell flux was low or decreasing, and vice versa. In spite of the changes in flux values following administration of a skin extract, the 3(H)TdR labelling indices were reduced only after a delay of 10 h, confirming previous results.

Controversies in mycosis fungoides

Most clinicians agree that mycosis fungoides is the prototypic cutaneous T cell lymphoma. However, certain clinical characteristics indicate that this disorder may begin as a reactive rather than a neoplastic process. The concept of a nonneoplastic etiopathogenesis of mycosis fungoides is further supported by recent data on the function of Langerhans cells, a population of epidermal cells known to play a critical role in immune surveillance and the development of contact sensitivity. It has been suggested that chronic occupational exposure to environmental allergens results in persistent antigenic stimulation, leading to a breakdown in immune surveillance and eventually, malignancy. Modern laboratory technics have enhanced the clinician's ability to diagnose and stage mycosis fungoides. Data obtained from such studies have indicated that systemic spread may occur much earlier in the course of disease than has previously been appreciated. The therapeutic implications of such knowledge are as yet uncertain.

Some Biochemical Properties of Pemphigoid Antigen Bound to the Surface of Dissociated Epidermal Basal Cells

Bullous pemphigoid antigen (BP Ag) is a cell surface marker of epidermal basal cells. The functional role of this molecule is unknown. Epidermal cell suspensions obtained by trypsinization of skin show a population of epidermal basal cells with a polar rim of antigen as demonstrated by indirect immunofluorescence technique. This study shows that treatment of these cells suspensions with a variety of proteolytic and glycosidic enzymes failed to remove the antigen from these basal cells. BP Ag was also stable upon incubation with distilled water, Triton X-100, PBS, and 1 M NaCl. Treatment of epidermal basal cells with 2 N NaSCN, 1% periodic acid, and 4 M urea, as well as acidic pH or 56 degrees C temperature, abolished the reactivity of these cells with BP antibodies.

Receptors for Complement on Langerhans Cells

A population of guinea pig epidermal cells, identified as Langerhans cells, formed rosettes with sheep erythrocytes coated with IgM immunoglobulin and C3b (EAC1-3b) but not with intermediates carrying only C1, C14b, or C14b2a. These findings were unusual since most other cells expressing C3b receptors also express C4b receptors. To investigate whether these results were the consequence of a limited number of C4b molecules on the cells, EAC14b cells were prepared with increased amounts of C4b (15 to 250 micrograms on 10(9) cells). EAC14b rosette formation was found with a maximal number when there were 3,000 molecules per cell, a 6-fold excess over that found in previous experiments. One could inhibit this rosette formation by fluid phase C3b as well as by fluid phase C4b, suggesting proximity or possible identity of these 2 receptors.

Complement receptors on guinea pig epidermal Langerhans cells.

Abstract A population of guinea pig epidermal cells possessed the ability to form rosettes with IgM antibody-sensitized sheep erythrocytes coated with purified human C3b (SEAIgMC1-), but not with intermediates carrying C1, C4, or C2. This population of rosette-forming epidermal cells was identified as Langerhans cells (LC) ultrastructurally and by LC depletion and enrichment studies. In addition, these cells were able to bind fluid phase C3b, which inhibited any subsequent SEAIgMC1-3b rosette formation. Rosette formation was also inhibited after SEAIgMC1-3b pretreatment with beta 1H and C3b-inactivator. LC were shown to possess trypsin-resistant C3b and Fc receptors, and unlike the temperature-independent nature of LC Fc-rosette formation, the ability of LC to form C3 rosettes was a temperature-dependent process. The finding of C3b receptors on the surface of guinea pig epidermal LC supports the concept that they are of the phagocytic monocyte-macrophage family.

Keratinocyte substrate adhesion is magnesium-dependent and calcium-independent

Primary cell cultures were prepared from guinea pig epidermis and six days old mice kidneys and hearts. Along with subcultures of Hep cells, plating experiments were performed using media devoid of bivalent cations containing dialzyed fetal calf serum. Upon stepwise supplementation with either calcium ++ or magnesium ++, keratinocytes displayed a unique dependency on magnesium ++ for cell attachment, whereas all other cell types could make use of either of these ions. Melanocytes, being a minority component of the epidermal cell population, do not conform to the predilection of keratinocytes for magnesium ++. Epidermal cell cultures prepared in media containing only calcium ++, therefore, result in pure melanocyte cultures.

Practical and Theoretical Considerations in the Use of the Mouse Foot System to Derive Epithelial Stem Cell Survival Parameters

A series of experiments investigating the effects of 1, 2, 4, 10, and 20 dose fractions of x rays on mouse foot skin are reported. These include data for levels of acute gross reactions from dry to full moist desquamation. We have shown the following for the irradiated epidermal stem cell population of the mouse foot. (1) Detectable proliferation was not found for regimes employing 10 daily dose fractions. (2) Significant interexperimental variation occurred which did not result from changes in cellular radiosensitivity. (3) The cell-survival equation obtained from data limited to reactions below the point of moist desquamation was not different from that obtained from higher reaction data. (4) The absolute target cell-survival levels corresponding to our mean reaction scale were established using published skin clone data and extended down to 4 x 10/sup -8/, and the clonogenic population was estimated as 0.6 to 3.0 x 10/sup 7/. (5) The relative radiobiological usefulness of the various levels of acute reactions has been characterized. (6) Skin-reaction scores obtained by averaging reactions over 7 days encompassing the peak response gave the same results with fewer readings than the conventional 22-day averaging period.

Ultrastructure of lineus ruber (rhyncocoela) epidermis

Recent evidence indicates that nemertean epidermis is capable of absorbing certain organic solutes from sea water via mediated transport mechanisms, as well as secreting mucoid substances. Morphological studies suggest that these functions may be restricted to distinct epidermal cell populations. Mucous secretion at the free surface of the epidermis is the result of synthesis and release activities of cells in both the epidermis and dermis (cutis). Secretion of dermal origin passes through the epidermis to the worm's exterior in slender cytoplasmic processes ( canaux d'evacuation) in the form of membrane bound vesicles. A single gland cell type, located entirely within the epidermis, releases externally a granular product histochemically identified as largely protein plus some amount of carbohydrate with low periodic acid-Schiff's reactivity. The close juxtaposition of granular endoplasmic reticulum and Golgi apparati to the secretory material is consistent with the composition of this secretory product. Interstitial cells possess microvilli projecting from their apical surface, in addition to cilia. The outer surface of the plasmalemma covering these ciliary projections is unadorned, but microvilli possess a fuzzy coat. At the peripheral ends of the microvilli, the coat is filamentous, while at their base the coat consists of foliate structures. Cationic colloidal iron binding suggest that the filamentous portion of the fuzzy coat contains the greatest proportion of the acidic surface charge. The presence of periodic acid-Schiff's positive material in this region suggests that the fuzzy coat also contains carbohydrate. Lateral boundaries of the interstitial cell lacks obvious junctional specializations; however, the apical 150 nm intracellular space narrows to 40 nm and continues in a tortuous interdigitating path to the base of the adjacent interstitial cells. Where the apex of these cells is broad, the interdigitations are shallow, but the basal half of the interstitial cells have deep complex infoldings. Cytoplasmic organelles other than the nucleus, mitochondria and some granular endoplasmic reticulum, are restricted to the apical half of the cytoplasm. The presence of closely apposed Golgi complexes and smooth endoplasmic reticulum, multivesicular bodies, lysosome-like dense vesicles and coated vesicles suggests that these cells may play a role in intracellular digestion of phagocytized paniculate matter from the external environment. The amplification of the interstitial cell's free surface suggests that these cells are primarily responsible for mediated solute transport across the epidermis.

Growth Regulation in X-irradiated Mouse Skin the Possible Role of Chalones

Extracts of hairless mouse skin were tested for their content of epidermal G1 inhibitor and G2 inhibitor at daily intervals after X-irradiation with 4 500 or 2 250 rad. After either dose the skin extracts lacked G1 inhibitory activity on days 5 and 6 respectively after irradiation. This coincided with the time when the epidermal mitotic rate again became normal and started a period of over-shoot. The time interval of 5-6 days corresponds to the turnover time of the differentiating cells in hairless mouse back epidermis. The findings indicate that the proliferating cells in epidermis can respond to changes in local chalone concentration, even after X-irradiation at the tested doses, and that the irradiated epidermal cell population still retains some important properties inherent in a cybernetically regulated system. The local G2-inhibitory activity also varied after irradiation, but these variations could not be directly related to the corresponding mitotic rates.

Epidermal Langerhans cells express Ia antigens

THE major histocompatibility complex (MHC) of mouse and man controls the expression of several cell surface antigens1. The classical transplantation antigens are present on most if not all adult, nucleated cells. However, molecules controlled by the immune response region of the MHC display a much more restricted tissue distribution. The immune response-associated antigens (the Ia antigens in the mouse and HLA-D antigens in man) seem to be integral parts of the plasma membrane of B and T lymphocytes, macrophages, spermatozoa, and epidermal cells2. The physiological role of the Ia antigens is far from understood but their participation in various immunobiological events is well documented (for a review, see ref. 3). In addition to their role as triggers in the mixed leukocyte reaction4, the Ia antigens are required for collaboration between T and B lymphocytes5 and between macrophages and T cells6. Since all known functions of the Ia antigens pertain to the immune system it seemed that they should be expressed on an epidermal cell population involved in immune reactions. We therefore set out to investigate which of the three cell types of epidermis, keratinocytes, melanocytes, and Langerhans cells, expresses the Ia antigens, and from the results of fluorescent antibody staining we conclude that it is the Langerhans cells.

The cell cycle in psoriasis: a reappraisal.

The current belief that the clinical manifestations of psoriasis (excessive scaling) are due to a twelve-fold speeding up or shortening of the cell division cycle time of the germinative cells in psoriatic epidermis (from 457 to 37-5 h) is shown to be incorrect. A new concept is introduced--that the germinative layer in human epidermis is composed of not one, but three separate and distinct populations of epidermal cells. First, there are cycling cells which are actively moving through the cell cycle. Then there are two categories of non-cycling cells (blocked in the G1 or the G2 periods of the cell cycle) which are capable of moving into the proliferative pool upon specific stimulation. Thus, increased epidermal cell proliferation in active lesions of psoriasis would be brought about mainly by a recruitment or a relase of the two categories of non-cycling cells. The idea that germinative epidermal cells are primarily non-cycling, leads to the suggestion of focusing attention on non-cycling cells (rather than on cycling cells) for the control and treatment of psoriasis. It might be worthwhile considering treating psoriatic patients during periods of clinical remission--with factors to keep the germinative cells in the non-cycling state--rather than during psoriatic flare up--with cancer chemotherapy drugs.

EFFECT OF MECHANICAL STIMULATION ON CELL PROLIFERATION IN MOUSE EPIDERMIS AND ON GROWTH REGULATION BY ENDOGENOUS FACTORS (CHALONES)

Mechanical stimulation of dorsal mouse skin by skin massage or removal of the horny layer results in a mutually comparable increase in DNA-labelling and mitotic activity. However, only after injury such as removal of the horny layer hyperplasia develops. This phenomenon, called "hyperplastic transformation" is characterized by a transient abolition of the epidermal G1 chalone responsiveness. There is some indication that the susceptibility to a heat labile factor, probably the epidermal G2 chalone, is not affected. Skin massage neither interferes with the responsiveness to epidermal G1 chalone nor induces "hyperplastic transformation". Mouse tail epidermis shows a "functional hyperplasia" and responds to the G1 chalone. To explain these observations, it is assumed that the epidermal stem cell population is heterogeneous consisting of G1 chalone-sensitive and G1 chalone-insensitive cells.

Antibodies to basal epidermal cells in patients with basal or squamous cell carcinoma.

Circulating antibodies directed against cytoplasmic antigens of basal cells of normal human epidermis have been reported in association with various skin diseases. Since they have been found in patients with malignant melanoma it was proposed to investigate whether these antibodies are associated with other epidermal tumors such as basal or squamous cell carcinoma. With indirect immunofluorescence it was shown that sera from patients with basal (20%) and squamous cell carcinoma (16%) contained these antibodies. They could be demonstrated by cytoplasmic fluorescence of the basal epidermal cell layer. These antibodies occured almost as frequent as in malignant melanoma sera. However they do not seem to be tumorassociated as they were found in sera from patients with various benign dermatoses, with tumors of extraepidermal origin and even sporadically in sera from natural antibodies which were identified by cytoplasmic fluorescence of the outer epidermal cells, suggesting two antigenically different epidermal cell populations.

Seria cultivation of strains of human epidemal keratinocytes: the formation keratinizin colonies from single cell is

Human diploid epidermis epidermal cells have been successfully grown in serial culture. To initiate colony formation, they require the presence of fibroblasts, but proliferation of fibroblasts must be controlled so that the epidermal cell population is not overgrown. Both conditions can be achieved by the use of lethally irradiated 3T3 cells at the correct density. When trypsinized human skin cells are plated together with the 3T3 cells, the growth of the human fibroblasts is largely suppressed, but epidermal cells grow from single cells into colonies. Each colony consists of keratinocytes ultimately forming a stratified squamous epithelium in which the dividing cells are confined to the lowest layer(s). Hydrocortisone is added to the medium, since in secondary and subsequent subcultures it makes the colony morphology more oderly and distinctive, and maintains proliferation at a slightly greater rate. Under these culture conditions, it is possible to isolate keratinocyte clones free of viable fibroblasts. Like human diploid fibroblasts, human diploid keratinocytes appear to have a finite culture lifetime. For 7 strains studied, the culture lifetime ranged from 20-50 cell generations. The plating efficiency of the epidermal cells taken directly from skin was usually 0.1-1.0%. On subsequent transfer of the cultures initiated from newborns, the plating efficiency rose to 10% or higher, but was most often in the range of 1-5% and dropped sharply toward the end of their culture life. The plating efficiency and culture lifetime were lower for keratinocytes of older persons.

Different populations of pig epidermal cells: isolation and lipid composition.

Preparations representing populations of (a) basal and spinous cells, (b) granular cells, and (c) stratum corneum cells were obtained by successive treatments of epidermal slices from pig skin with dilute buffered trypsin solutions. Total lipids accounted for about 8% of the cell dry weight in each of the three populations. Phospholipids, which predominated in the basal and spinous cells, accounted for only 21% of the total lipids in the granular cells and less than 0.1% in the stratum corneum. The latter cells contained more cholesterol (23% of total lipid) than either the granular cells (18%) or the basal and spinous cells (8%). The proportion of ceramide was also much higher in the stratum corneum (17%) and granular cells (9%) than in the basal and spinous cells (1%). The relative amounts of glycosphingolipid (glucosylceramide) and cholesteryl sulfate in the total lipids of stratum corneum cells were less than half those in the granular cells and basal and spinous cells. A novel phospholipid was a major component (26% of total) of the phospholipids from granular cells. The compound, which was partially characterized, contained phosphorus, fatty acids, and glycerol (molar ratio 1:3:2) and appeared to be a neutral derivative of phosphatidic acid.

Epidermal mucus and the reproduction of a crinoid echinoderm.

THE unstalked crinoid Comanthus japonica spawns during the first part of October each year1,2. For a study of gametogenesis2 specimens of Comanthus were collected periodically over 14 months. During these collections one of us (J. G.) noticed that the animals became unusually slimy to the touch during the six to eight weeks that preceded spawning. This transient slimyness is correlated with an enlargement of an epidermal mucous cell population. The general position of the mucous cells is shown in Fig. 1 in which they are darkly stained. In both male and female genital pinnules these cells occur mostly in the oral and lateral body wall. Each individual mucus cell is oval and contains a single nucleus. The cytoplasm stains with beta- to gamma-metachromasia in azure A. In addition the cytoplasm stains strongly with alcian blue at pH 3 but fails to stain with periodic acid–Schiff. These histochemical criteria indicate an abundance of sulphated acid mucopolysaccharides (possibly mixed with non-sulphated acid mucopolysaccharides). It is not known if similar mucous cells occur in the arms and central mass of the crinoids since these body regions were not preserved for histology.