Sections Of Normal Human Skin Research Articles

Specific detection of anti-cell surface antibodies in herpes gestationis sera.

We examined 42 herpes gestationis sera with immunofluorescence of normal human skin sections, and found that anti-keratinocyte cell surface antibodies were detected specifically in 10 herpes gestationis sera. The diagnosis of these herpes gestationis cases was confirmed by detecting antibodies against the 180 kD bullous pemphigoid antigen with immunoblotting of its fusion protein. The results of immunoadsorption assay using baculoproteins of both pemphigus vulgaris and pemphigus foliaceus antigens indicated that the herpes gestationis sera did not recognize common pemphigus antigens. Immunoblotting of human epidermal extracts and immunofluorescence of various tissues also suggested that the sera did not recognize any other desmosomal components or paraneoplastic pemphigus antigens. The significance of this reactivity is unclear. However, because no control bullous pemphigoid sera showed this reactivity, it may suggest a different pathophysiology between herpes gestationis and bullous pemphigoid.

Dermal microvascular endothelial cells express CD32 receptors in vivo and in vitro.

Immune complexes are thought to be the major cause of cutaneous necrotizing vasculitis, but the mechanism of immune complex targeting to specific vessels is largely unknown. In myelomonocytic cells, immune complex binding and receptor-mediated endocytosis are mediated by Fc gamma R. We asked whether dermal microvascular endothelial cells (DMEC) express Fc gamma Rs. In cryostat sections of normal human skin, mAb IV.3 or AT10, both recognizing CD32 (Fc gamma RII), localizes to the luminal surface of DMEC of the superficial but not of the deep vascular plexus. All DMEC do not express CD16 (Fc gamma RIII) or CD64 (Fc gamma RI) molecules. Adult skin-derived DMEC in culture express CD32 (Fc gamma RII) molecules, as measured by FACS, but are negative for CD16 or CD64. HUVEC, tested for comparison, do not express CD16, 32, or 64 proteins. By reverse-transcriptase PCR and subsequent Southern blot analysis, the isoform of the CD32 molecule expressed on DMEC is determined as Fc gamma RIIa. HUVEC do not contain Fc gamma RIIa or Fc gamma RIIb mRNA. In DMEC, Fc gamma RIIa cross-linking results in immediate intracellular free Ca2+ ([Ca2+]i) concentration fluxes and in rapid internalization of the occupied receptors. We conclude that DMEC are equipped with fully functional Fc gamma RIIa molecules.

Identification of Functional Platelet-Activating Factor Receptors on Human Keratinocytes

Platelet-activating factor (PAF) is a potent inflammatory mediator that has been shown to be produced by human keratinocytes and is thought to play a role in cutaneous inflammation. Immunofluorescence and radioligand binding studies were used to characterize PAF receptors (PAF-R) on human keratinocytes and the human epidermoid cell lines A-431 and HaCaT. Indirect immunofluorescence studies demonstrated anti-PAF-R staining of primary cultures of human keratinocytes, A-431 cells, and HaCaT cells. Primary cultures of human fibroblasts and the melanoma cell line SK-30 failed to show immunostaining above that seen with control antiserum. With indirect immunofluorescence studies of sections of normal human skin, a granular anti-PAF-R staining pattern was noted on the keratinocyte cell membranes. A-431 cells readily metabolized PAF by deacetylation-reacylation at 37 degrees C, but not at 4 degrees C. Binding studies on crude membrane preparations of A-431 cells conducted at 4 degrees C demonstrated specific binding that reached saturation by 120 min. Scatchard analysis of PAF binding data revealed a single class of high-affinity (KD = 6.3 +/- 0.3 nM) PAF binding sites. The immunofluorescence and radioligand binding sites were shown to be functional PAF-Rs, as 10 pM to 1 microM PAF increased intracellular calcium in primary cultures of human keratinocytes, A-431 cells, and HaCaT cells, whereas PAF treatment of primary cultures of human fibroblasts or the melanoma cell line SK-30 did not result in changes in the intracellular calcium concentration. The structurally dissimilar PAF-R antagonists CV-6209, Ro19-3704, and alprazolam all inhibited the PAF-induced calcium changes in A-431 cells. The CV-6209 inhibition was seen at doses that competed with the PAF binding to these cells. These studies provide the first evidence for the presence of a functional PAF-R expressed on human keratinocytes, suggesting that this lipid mediator may play an important role in normal keratinocytes or in inflammatory dermatology.

Immunohistochemical localization of thrombomodulin in normal human skin and skin tumours

Thrombomodulin (TM) expression has been investigated in sections of normal human skin, in cultured normal human keratinocytes, and in a variety of skin tumours. TM was present in squamous epithelial cells in the spinous layer of normal epidermis and in the outer root sheath of hair follicles, but was absent in the cells of the basal layer. It appeared to be predominantly localized to the cell membrane and the intercellular bridges in these areas. Cultured normal human keratinocytes demonstrated functionally active constitutive TM expression on their cell surface. Immunoperoxidase staining of skin tumours using anti-human TM antibodies demonstrated a typical cell membrane positivity in tumours with squamous or hair follicle differentiation. Basal cell carcinomas showed TM expression only in areas where incomplete squamoid metaplasia occurred. Sweat gland tumours and lesions of the melanogenic system failed to express TM. The localization of TM by immunostaining in various benign and malignant skin tumours typically correlated with their normal skin element of origin. The physiological significance of TM expression in the epidermis is currently undefined.

Polyclonal antibodies against human melanocortin MC 1 receptor: preliminary immunohistochemical localisation of melanocortin MC 1 receptor to malignant melanoma cells

Peptides of 11 and 15 residue lengths were synthesised according to the sequence of the N-terminal region of the human MC 1 melanocyte stimulating hormone receptor. The peptides were conjugated to thyroglobulin and used for preparation of antisera in the rabbit. Each of the conjugates raised antisera which showed high titre and specificity for its respective peptide antigen when evaluated in an ELISA test. Both types of antisera immunostained MC 1 receptor expressing COS-7 cells. By contrast, the sera did not stain control COS-7 cells not expressing the MC 1 receptor. Moreover, preimmune sera or antiserum preadsorbed with its respective peptide did not stain the MC 1 receptor expressing cells. The antisera were used to immunostain sections of normal human skin, as well as samples of cutaneous malignant melanoma tumours obtained from a patient. The cells of the melanoma tumours were very strongly immunostained with the MC 1 receptor antisera. By contrast, melanocytes which were present in the normal skin could not be visualised with our antisera.

Keratinocytes constitutively express the Fas antigen that mediates apoptosis in IFN gamma-treated cultured keratinocytes.

The Fas antigen is a cell surface protein that can mediate apoptosis in many cell types. Although its physiological function is still unclear, recent evidence indicates that this surface molecule is involved in apoptosis in the immune system and the liver. The epidermis is an organ that undergoes terminal differentiation with the eventual death of keratinocytes, and it has been suggested that this is a specialized form of apoptosis. In the present study, we examined whether or not the Fas antigen is involved in keratinocyte apoptosis. Immunoreactivity for the Fas antigen was found throughout the epidermis in normal human skin sections and cultured normal human keratinocytes, and mRNA for the Fas antigen was found to be constitutively expressed in normal epidermis and cultured normal keratinocytes by RT-PCR analysis. To determine whether the Fas antigen in keratinocytes is functional, we used a cytotoxic monoclonal antibody (mAb) against the Fas antigen to induce apoptosis. This antibody did not induce apoptosis of cultured keratinocytes even though they expressed the Fas antigen. We then tested the ability of several cytokines (TGF beta, TNF alpha and IFN gamma) to induce Fas-mediated keratinocyte apoptosis. Only pretreatment with IFN gamma followed by the addition of the anti-Fas mAb induced apoptosis, as assessed by cell viability, morphological changes and ultrastructural characteristics, suggesting that constitutive expression of the Fas antigen is not sufficient to induce apoptosis in keratinocytes and that keratinocyte apoptosis via the Fas antigen-mediated mechanism may require the activation of keratinocytes by IFN gamma, which is thought to be produced by activated T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

A Case of Bullous Pemphigoid with Antidesmoplakin Autoantibodies

We present an 84-year-old Japanese male showing typical features of bullous pemphigoid (BP). However, immunofluorescence of normal human skin sections revealed concurrent anti-basement-membrane-zone and anti-keratinocyte-cell-surface autoantibodies in the serum. With immunoblotting, the patient's serum reacted with desmoplakins I and II, as well as with both the 230-kD and the 180-kD BP antigens. The studies for this case may provide us with an insight to understand the occurrence of antidesmoplakin antibodies in paraneoplastic pemphigus.

Gamma delta T-cell receptor-positive cells of human skin. II. Appearance in delayed-type hypersensitivity reaction.

In order to investigate the distribution and involvement of human gamma delta T-cell receptor-positive (TCR+) cells in delayed-type hypersensitivity reactions of the skin, we examined the occurrence and kinetics of gamma delta TCR+ cells during skin reactions of allergic contact dermatitis. In normal human skin sections, gamma delta TCR+ cells were scarce. In allergic contact dermatitis from DNCB, increased gamma delta TCR+ cells were observed both in the epidermis and in the dermis from 48 h after the challenge. Most of the gamma delta TCR+ cells were TCR delta 1+ delta TCS1- BB3+ Ti gamma A+ (V delta 1- V delta 2+ V gamma 9+). The percentage of gamma delta TCR+ cells in the peripheral blood remained unchanged and a few gamma delta TCR+ cells in the skin lesions proliferated in situ. It is suggested that the gamma delta TCR+ cells in skin lesions of allergic contact dermatitis may not be involved in initiation of delayed-type hypersensitivity but may have some other roles responding to factors induced in the reaction.

Human Keratinocytes Synthesize, Secrete, and Degrade Acetylcholine

We previously reported that normal human keratinocytes express muscarinic receptors, and that acetylcholine induces attachment of these cells to each other. We have now studied the ability of human keratinocytes to synthesize, secrete, and degrade acetylcholine. To detect and localize the synthesizing enzyme choline acetyltransferase and degrading enzyme acetylcholinesterase, cultured cells and cryostat sections of normal human skin were pre-incubated with specific monoclonal antibodies and stained with an avidin-biotin complex/alkaline phosphatase. The choline acetyltransferase activity was assessed by the conversion of [3H]acetyl CoA to [3H]acetylcholine, and newly synthesized [3H]acetylcholine was detected using thin-layer chromatography. The acetylcholinesterase activity was measured spectrophotometrically. Both cholinergic enzymes were present in cultured keratinocytes, and in basal, spinous and granular epidermal cell layers. Choline acetyltransferase was visualized in the vicinity of cell nuclei, and acetylcholinesterase was observed in or near cell membranes. Newly synthesized acetylcholine was detected in both cell homogenates and culture supernatants. The estimated Vmax of the synthesis of labeled acetylcholine by homogenized keratinocytes was about 20 pmoles acetylcholine produced/mg protein/min at 37 degrees C. A single keratinocyte synthesized a mean of 2 x 10(-17) moles, and released 7 x 10(-19) moles acetylcholine per minute. Both cell homogenates and culture supernatants exhibited similar acetylcholinesterase activities indicating that human keratinocytes secrete acetylcholinesterase, too. Thus, we have demonstrated that normal human keratinocytes possess choline acetyltransferase and acetylcholinesterase, and synthesize, store, release, and degrade acetylcholine. Because human keratinocytes can also respond to acetylcholine, we believe that keratinocyte acetylcholine works in the epidermis as a local hormone.

Interleukin 1 immunoreactivity in sebaceous glands.

Interleukin 1 (IL-1) immunoreactivity in sebaceous glands was studied in paraffin sections of normal human skin. A panel of antibodies against IL-1 alpha and beta was tested using an immunoperoxidase labelling method. All the antibodies showed a similar specific labelling pattern: both glandular and ductal cells were immunoreactive for both IL-1 alpha and beta, provided optimal tissue fixation was used.

Expression of loricrin is negatively controlled by retinoic acid in human epidermis reconstructed in vitro

Abstract . In epidermis, the last steps of keratinocyte differentiation are characterized by the covalent cross-linking of cornified envelope precursors such as involucrin and loricrin, a hydrophobic protein recently described in mouse and human epidermis. In situ hybridization of normal human skin sections with a human loricrin cRNA probe and immunolabeling with an antiserum directed against a synthetic peptide corresponding to the carboxyterminus of human loricrin revealed the presence of loricrin transcripts and protein in the granular layers of epidermis. In human epidermis reconstructed in vitro by growing keratinocytes on dermal equivalents, loricrin and loricrin mRNAs were also restricted to granular cells, but their amounts seemed higher than in epidermis from skin biopsies. The reactivities for both loricrin and loricrin mRNAs were abolished by a treatment of the cultures with a retinoic acid concentration (10 −6 M) provoking a complete inhibition of terminal epidermal differentiation (parakeratosis). Thus, the regulation of loricrin synthesis is different from that of another envelope precursor, involucrin, which does not seem to be significantly modulated by retinoic acid. Together with the well-documented inhibition of epidermal transglutaminase by retinoic acid, our results provide a molecular basis for the inhibition of cornified envelope formation by retinoic acid.

The Subclass Distribution of IgG Autoantibodies in Cicatricial Pemphigoid and Epidermolysis Bullosa Acquisita

To study the subclass distribution of autoantibodies and their complement-fixing capacity in cicatricial pemphigoid (CP) and epidermolysis bullosa acquisita (EBA) we studied the sera from 23 patients by both indirect immunofluorescence (IIF) on 4-microns cryostat sections of normal human skin and immunoblotting of epidermal or dermal extracts. Monoclonal antibodies of strict specificity for human IgG subclasses were used. Sera from 20 patients with BP served as controls. In addition, total IgG subclass levels were determined by indirect competitive ELISA in all sera. Complement binding capacity was studied by IIF using antibodies to C3 after incubation of skin section with autoantibodies and source of fresh complement. CP autoantibodies reacting with the 230-240 kD and/or the 180-kD epidermal bands showed an IgG4/IgG1 subclass restriction, with a predominance of IgG4 in 10 cases, of IgG1 in four. In BP sera, IgG4 and IgG1 autoantibodies were detected with a similar frequency (100% and 83%, respectively). In EBA sera, autoantibodies reacting with the 290 kD and 145 kD dermal bands also showed an IgG1/IgG4 restriction. Concordant results were obtained by IIF. However, the IIF method had a lower sensitivity for the detection of IgG4 CP antibodies and IgG1 EBA antibodies than immunoblotting. Finally, when CP antibodies were analyzed for their complement-binding activity, it was found that sera containing IgG4 autoantibodies alone never fixed complement whereas all complement-fixing CP sera had IgG1 autoantibodies, suggesting that only this subclass of antibodies is capable of fixing complement.

Transforming growth factor‐β1 localization in normal and psoriatic epidermal keratinocytes in situ

Transforming growth factor-beta 1 (TGF beta 1) is a potent inhibitor of epithelial cell proliferation and its effects on growth and differentiation have been extensively characterized in cultured keratinocytes. We used two TGF beta 1-specific polyclonal antibodies (anti-LC and anti-CC) to determine the presence of TGF beta 1 peptide in keratinocytes in sections of normal human skin in situ and in both plaque and nonplaque skin from individuals with psoriasis. In contrast to the differentiation phenotype expressed by keratinocytes in normal epidermis, keratinocytes in the psoriatic plaque exhibit a hyperproliferative/regenerative differentiation phenotype. Anti-TGF beta 1 staining was observed primarily in the epidermis. Anti-LC TGF beta 1 antibody stained nonproliferating, differentiated suprabasal keratinocytes intracellularly in normal skin but did not stain psoriatic plaques from five of seven patients. In contrast, anti-CC TGF beta 1 antibody stained suprabasal keratinocytes extracellularly in psoriatic plaques, but did not stain normal skin. Both anti-LC and anti-CC stained suprabasal keratinocytes intracellularly in nonplaque psoriatic skin. Thus, the conformation or structure of TGF beta 1 and its localization vary in keratinocytes with distinct differentiation phenotypes suggesting that TGF beta 1 is a potential modulator of keratinocyte differentiation in vivo. Selective association of TGF beta 1 with nonproliferating keratinocytes in the suprabasal layers of the epidermis and its exclusion from the proliferating keratinocytes in the basal layer suggest that it may be a physiological regulator of keratinocyte proliferation. In addition, the intracellular localization of TGF beta 1 peptide in both normal and psoriatic keratinocytes suggests that it is constitutively synthesized by epidermal keratinocytes in vivo.

Epithelial Polymeric Immunoglobulin Receptors

The secretory immune system, which leads to secretion of polymeric immunoglobulins along mucosal surfaces, has not been shown to have any definite role in cutaneous immunology, although the polymeric immunoglobulin receptor, secretory component (SC), has been found in sweat glands and possibly in the epidermis. The purpose of this study is to examine normal human skin and cultured human keratinocytes for the presence of SC. Positive staining for SC was found in sections of normal human skin along the basement membrane zone with use of a polyclonal antibody to SC and focally on the surfaces of epidermal cells with use of a monoclonal antibody to SC. Granular cell-surface fluorescence of an intensity far less than that of the positive control HT 29 cells was seen when cultured human keratinocytes were stained for SC by indirect immunofluorescence (IF). Study of lysates of both HT 29 cells and HK by immunoblotting have been negative, perhaps due to destruction of the protein or loss of antigenicity during the extraction process. If human keratinocytes are capable of expression of SC, and the receptor can interact with IgA and IgM, this might be a mechanism for protection of the skin from microbial agent or foreign antigens and might be relevant to the deposition of IgA seen in certain skin diseases.

Serum amyloid P component binds to cell nuclei in vitro and to in vivo deposits of extracellular chromatin in systemic lupus erythematosus.

Serum amyloid P component (SAP) is the single plasma protein that, from the milieu of whole normal human serum, undergoes specific calcium-dependent binding to isolated DNA and chromatin in vitro. We now report for the first time that SAP in whole serum also undergoes calcium-dependent binding to nuclei of epidermal cells in sections of normal human skin and to nuclei of fixed Hep-2 cells, a human epithelial cell line. Furthermore, and most importantly, SAP was detected in association with unusual globular dermal deposits of nuclear material in skin biopsies from two patients with systemic lupus erythematosus. This is the first evidence for binding of SAP to extracellular chromatin in vivo and supports the idea that SAP may have an important physiological role in the disposal of this material.

IgA Class Antibodies in Dermatitis Herpetiformis: Reaction With Tissue Antigens

The mechanism for deposition of IgA in dermatitis herpetiformis (DH) remains unclear. To test the hypothesis that a circulating IgA class antibody in DH patients binds to constituents of normal human skin, we employed the highly sensitive methods of immunoblotting and indirect immunofluorescence. Sera from 64 DH patients, 67 randomly selected normal control subjects, 29 histocompatibility locus antigen (HLA) B8/DR3/DQw2 controls, and 12 psoriatic patients were tested for IgA binding to various substrates, including dermal and epidermal extracts, fibroblast and keratinocyte supernatants, monkey esophagus sections, and whole and saline-split normal human skin sections. Significant differences observed among the groups in the frequency of detectable IgA antibodies reacting with various substrates were as follows: 1) IgA antibodies in 30% of both DH and HLA B8/DR3/DQw2 sera bound to a 60-Kd protein in dermal extracts (p less than 0.25 versus non-HLA matched controls); 2) IgA antiendomysial antibodies were present in 38% of DH patients (predominantly those not on gluten-free diets), whereas both normal control groups had frequencies of 5-10% (p less than 0.025); 3) there was more nonspecific IgA antibody-binding to dermal, epidermal, and bovine proteins in DH and HLA control sera than in normal sera; and 4) IgA antibodies directed against the basement membrane were present with an increased frequency of 25% in both DH and HLA B8/DR3/DQw2 sera (p less than 0.1 versus non-HLA matched controls). Therefore, these results do not support the hypothesis that there is an unique antigen within normal human skin to which IgA antibodies from DH sera bind.

Immunohistochemical localization of calmodulin in normal and psoriatic epidermis.

Calmodulin (CAM) is a major Ca2+-binding intracellular protein of eukaryotic cells. As well as having other functions, it has been related to proliferation, cell cycle, differentiation, and spatial arrangement of intermediate filaments (for overview see [2]). CaM gained particular attention in psoriasis research with publication of the first report on raised activity in psoriatic plaques, by van de Kerkhof and van Erp in 1983 [1, 3, 7 9 , 11]. Nevertheless, no information is available about the intraepidermal distribution of this protein in psoriatic skin. As far as we know, there is only one recent report of immunohistochemical CaM detection on paraffin sections of normal human skin, suggesting a homogeneous distribution in all living cell layers [5]. Therefore, using histochemical techniques, we investigated epidermal CaM in normal and psoriatic skin. Skin biopsy specimens were obtained from healthy volunteers, and lesional and nonlesional psoriatic skin from patients after local analgesia. The tissues were snapfrozen in liquid nitrogen and processed to unfixed frozen sections of 4-1am thickness. Potyclonal anti-CaM was raised in rabbits, as previously described [10]. The working dilution was 1 : 100 in phosphate-buffered saline (PBS), pH 7.4, supplemented with 0.2% bovine serum albumin and 0.5 ml Tween 20 per liter. Tissue sections were treated with PBS-Tween 20 containing 5% goat serum for 20 min at room temperature and washed twice. Anti-CaM was added

Identification of CD4+, 2H4+ (T8 gamma +) suppressor-inducer cells in normal human epidermis and superficial dermis.

Immunohistological staining of frozen sections of normal human skin demonstrated the presence of significant numbers of mononuclear cells expressing novel epitopes associated with CD4-positive suppressor-inducer functions. The cells were located around superficial vessels and within the basal layers of the epidermis and hair follicles. The antigen identified by the various antibodies has been shown to be functionally important in the induction of various suppressor cells capable of abrogating B cell responses to pokeweed mitogen. The presence in the skin of cells with possible down-regulatory functions in the immune response may be significant with respect to surveillance against neoplasms and control of appropriate responses to infectious agents.

Localization and In Vivo Activity of Epidermal Transglutaminase

The plasma membrane-associated transglutaminase is responsible for the formation of a cornified envelope during terminal differentiation of epidermal keratinocytes. We have studied the epidermal distribution of this enzyme ("epidermal transglutaminase") and its activity by fluorescence microscopy in histological sections of normal human skin and human skin grafted onto nude mice. Three different techniques were employed: (i) incubation of skin sections with a monoclonal antibody raised against a purified preparation of the enzyme; (ii) incubation of skin sections with dansylcadaverine, a fluorescent substrate of the enzyme, in the presence of Ca++ ions; and (iii) subcutaneous injection of dansylcadaverine into mice, at least 2 months after grafting. The first technique is supposed to detect all enzyme molecules carrying the epitope that is recognized by the antibody, even when the enzyme is catalytically not active; the second should decorate all sites in which membrane-bound transglutaminase activity is located, and the third detects only sites in which transglutaminase is active in vivo. With the first two techniques a broad band of plasma membrane associated fluorescence, reaching from the middle of the spinous layer to the stratum corneum, was detected in both normal and grafted skin. In vivo enzyme activity, however, was found to be restricted to one, or at most two, cell layers at the interface of the stratum granulosum and stratum corneum and to coincide with the layer in which the antigenicity of involucrin, a natural substrate of epidermal transglutaminase, disappeared.

The use of PIXE in experimental studies of the physiology of human skin epidermis

In order to understand the normal and pathological physiologies of the epidermal cells, the simultaneous determination of several elements in the different cellular strata is of crucial importance. In recent years the electron microprobe (EMP) has become an established technique in this field. Its high spatial resolution, in principle, allows measurements of various cell organelles. However, the limited (intrinsic) sensitivity of the EMP represents a serious drawback to the technique. The introduction of the proton microprobe (PMP) has significantly improved the sensitivity, although the ultimate spatial resolution of the PMP is much less than that of the EMP.When studying the elemental profiles in skin epidermis, it is possible to use skin sections with a thickness of the order of 10 μm, then the spatial resolution of the PMP is equal to or better than that of the EMP since the electrons are scattered to a significant degree in the sample. The characteristics of the two methods have been compared by analysis of parallel duplicate freeze-dried sections of normal human skin. The distributions of the elements P, S, Cl, and K, obtained with the two techniques, were in good agreement. In addition, the PMP provided distributions of the important elements Ca, Fe, and Zn.In a recently started study, the useful features of the PMP will be used for studying how efficient a barrier the skin is to nickel and chromate ions. A preliminary experiment has been performed by exposing cadaverous skin, not older than 24-h postmortem, to solutions of the two ions. After an 18-h exposure, samples were prepared by shock-freezing and sectioning. The first results from PMP analysis of these samples demonstrate the presence of a nickel and chromium gradient in the outer strata in the epidermis (mainly stratum corneum).A third experiment deals with the physiology of psoriatic skin. Calcium is an important element in the differentiation. Hence, the higher sensitivity of the PMP has been used in analysis of sections from psoriatic skin epidermis. Preliminary results are presented.