Increased cytotoxic sensitivity of YPC-1 tumor cells from mice treated with nitrosoureas.

The relative cytotoxic sensitivity of the YPC-1 tumor target cells from untreated mice and from animals treated with nitrosoureas was determined. The amount of 51Cr released from target cells increased significantly when the cells were obtained from treated mice. On the basis of the results of cold-target cytotoxicity inhibition assay, this enhancement was shown to be haplotype specific. The amount of 51Cr released from target cells of mice treated with N,N'-bis(chloroethyl)-N-nitrosourea decreased significantly when the tumor cells were first incubated with fibrinogen and transglutaminase. Based on these results and other published data, a model system is suggested. The model is based on the observation that tumors, and thus tumor antigens, at the cell surface are partly or completely covered by fibrinogen or fibrin. The enzyme transglutaminase is involved in the binding of the fibrinogen or fibrin to the cell surface. Accordingly, it is hypothesized that the nitrosoureas have a dual mode of immunotherapeutic activity. The carbamoylating properties inhibit the fibrin-binding activity of transglutaminase, thus preventing fibrin from covering up or coating the tumor cells and preventing the ability of sensitized effector cells to recognize the tumor-specific antigens in association with self H-2 antigens. The alkylating property of the nitrosoureas mainly concerns reactivity with the DNA of the tumor cells.

Platelet-activating factor antagonists (BN 52021 and BN 50730) inhibit tumor necrosis factor-alfa-mediated cytotoxicity on murine L929 tumor cells.

Tumor necrosis factor (TNF)-alfa has been described as a mononuclear phagocyte-produced cytotoxin that causes the necrosis and regression of some tumors. The mechanism of the cytotoxicity and the basis for the differential cytotoxic effects of TNF against cells of various origin remains unclear. It has also been reported, that murine TNF stimulates the production of platelet-activating factor (PAF) by cultured peritoneal macrophages, and that PAF enhances TNF production by alveolar macrophages. Furthermore, it is known that the synthesis and release of PAF are inhibited by plasma proteinase inhibitors. This study was devoted to investigate the effects of two specific PAF antagonists (BN 52021 and 50730), and a proteinase inhibitor (aprotinin; GordoxR) on the TNF-induced cytotoxicity in L929 murine fibroblasts. Our present findings indicate that TNF-induced cytotoxicity is inhibited in a dose-dependent manner by the PAF antagonists studied and by the kallikrein inhibitor aprotinin. These findings provide further evidence suggesting that PAF might be involved in the process of the TNF-alfa-induced cytotoxicity of L929 mouse fibroblasts.

A comparative study of the shedding process mouse erythrocyte binding receptors on peripheral blood lymphocytes from healthy donors and patients suffering from chronic lymphocytic leukemia.

The shedding process of the mouse erythrocyte binding receptors of human peripheral lymphocytes of a healthy donor group was compared to that of patients with chronic lymphocytic leukemia. The shedding process exhibited significant differences with respect to the groups tested, suggesting that the mouse erythrocyte binding receptors were altered during leukemic transformation or that the leukemic cells were fixed in a stage of maturation.

Suppressor function of peripheral blood mononuclear cells in patients with psoriasis vulgaris.

The suppressor activity of peripheral blood mononuclear cells was investigated in 25 patients with psoriasis vulgaris. In the psoriatic patients the suppressor activity was found to be significantly lower than in the control group, which suggests that the weak suppressor activity may play a role in the pathogenesis of this disease.

Peroxynitrite production, DNA breakage, and poly(ADP-ribose) polymerase activation in a mouse model of oxazolone-induced contact hypersensitivity.

Peroxynitrite-induced poly(ADP-ribose) polymerase activation has been implicated in the pathogenesis of various inflammatory conditions. Here we have investigated whether peroxynitrite and poly(ADP-ribose) polymerase may play a role in the pathophysiology of the elicitation phase of contact hypersensitivity. We have detected nitrotyrosine, DNA breakage, and poly(ADP-ribose) polymerase activation in the epidermis of mice in an oxazolone-induced contact hypersensitivity model. As tyrosine nitration is mostly mediated by peroxynitrite, a nitric-oxide-derived cytotoxic oxidant capable of causing DNA breakage, we have applied peroxynitrite directly on mouse skin and showed poly(ADP-ribose) polymerase activation in keratinocytes and in some scattered dermal cells. We have also investigated the cellular effects of peroxynitrite in HaCaT cells, a human keratinocyte cell line. We found that peroxynitrite inhibited cell proliferation and at higher concentrations also caused cytotoxicity. Peroxynitrite activates poly(ADP-ribose) polymerase in HaCaT cells and poly(ADP-ribose) polymerase activation contributes to peroxynitrite-induced cytotoxicity, as indicated by the cytoprotective effect of the poly(ADP-ribose) polymerase inhibitor 3-aminobenzamide. The cytoprotective effect of 3-aminobenzamide cannot be attributed to inhibition of apoptosis, as apoptotic parameters (caspase activation and DNA fragmentation) were not reduced in the presence of 3-aminobenzamide in peroxynitrite-treated cells. Moreover, poly(ADP-ribose) polymerase inhibition by 3-aminobenzamide dose-dependently reduced interferon-induced intercellular adhesion molecule 1 expression as well as interleukin-1beta-induced interleukin-8 expression. Our results indicate that peroxynitrite and poly(ADP-ribose) polymerase regulate keratinocyte function and death in contact hypersensitivity.

Immune-associated surface markers of human keratinocytes.

The results of a number of investigations have proved that human keratinocytes (HKs) possess the ability to synthesize and express cell surface moieties characteristic of effector and/or accessory cells of the immune system. The present paper summarizes the known immune cell surface features of HKs, reflecting their stage of activation and differentiation. The surface and functional characteristics of HKs suggest their monocyte/macrophage behavior, which fits in well with the presumed active involvement of HKs in the skin immune system.

Repopulation of Langerhans cells during wound healing in an experimental human skin/SCID mouse model.

The epidermal repopulation of Langerhans cells (LCs) during wound healing was examined using a human skin severe combined immunodeficient (SCID) mouse model. The experiments, were carried out after proving the human origin of keratinocytes repopulating the wound beds using the W6/32 monoclonal antibody. It was shown that CD1a- and HLA-DR-positive dendritic cells (mostly LCs) are already detectable 2 days after injury within the newly formed epithelium. In the excisional wounds investigated, neither HLA-DR nor ICAM-1 expression of human keratinocytes was observed. Our present data suggest that LC repopulation is an early event in the process of re-epithelization.

HHV-8 ELISA based on a one-step affinity capture of biotinylated K8.1 antigen.

The immunogenic envelope antigen gp35-37 of human herpesvirus-8 (HHV-8) is encoded by orfK8.1. An ELISA is described using streptavidin capture of bacterially expressed and biotinylated recombinant K8.1 antigen. The antigen capture strategy provides a simple and reliable method, which does not require high yield production and purification of the recombinant antigen before the serological assay. The specificity and sensitivity of the K8.1 ELISA were validated by gp35-37 envelope antigen Western blot and anti-lytic membrane immunofluorescence assay using lytically induced HHV-8 infected BCBL-1 cells. Under the established ELISA conditions, eight of the 10 Kaposi's sarcoma patients and five of the 180 healthy blood donors had IgG antibodies to K8.1 envelope antigen.

bcl-2 vs p53 protein expression and apoptotic rate in human nonmelanoma skin cancers.

BACKGROUND: A failure in the apoptotic response after severe genomic damage could facilitate cell transformation and tumor development, and a constitutive overexpression of either p53 or bcl-2 protein in nonapoptotic tumor cells could signify a defective bax-mediated apoptosis. OBJECTIVES: To investigate whether a negative correlation occurs between these 2 proteins in nonmelanoma skin cancer and whether overexpression of either protein is associated with a low rate of spontaneous apoptosis. DESIGN: Immunohistochemical study of nonmelanoma skin cancer archive material. SETTING: University referral center. PATIENTS: White patients with tumors on sun-exposed skin areas (ie, 17 basal cell carcinomas and 22 squamous cell carcinomas). MAIN OUTCOME MEASURES: Positivity for p53 and bcl-2 were scored semiquantitatively on 4 levels, and the percentages of apoptotic cells were determined. RESULTS: A significant negative correlation between p53 and bcl-2 expression was found in the basal cell carcinomas, but not in the squamous cell carcinomas, largely attributable to the low level of bcl-2 staining in the squamous cell carcinomas. Squamous cell carcinomas have a significantly higher number of apoptotic cells than basal cell carcinomas: 1.1% vs 0.6%, respectively. This spontaneous apoptosis decreases with increasing bcl-2 (in basal cell carcinoma), whereas it does not appear to be related to p53 level expression. CONCLUSIONS: These results indicate that a disturbance in either p53 or bcl-2 suffices to enhance skin tumor formation by suppressing apoptosis; bcl-2 appears to reduce the rate of spontaneous apoptosis, but an aberrant p53 expression does not, and this factor may solely affect the apoptosis from exogenous genotoxicity.

Cimetidine and a tamoxifen derivate reduce tumour formation in SCID mice xenotransplanted with a human melanoma cell line.

Histamine is produced by many cells expressing histidine decarboxylase (HDC), the enzyme responsible for the synthesis of histamine. Since melanoma cells and tissue contain relatively large amounts of histamine, the functional significance of histamine was examined using specific antihistamines in vitro and in vivo in the human melanoma cell line HT168 and severe combined immunodeficiency (SCID) mice. It was shown that the H2 receptor antagonist cimetidine when combined with N, N-diethyl-2-[4-(phenylmethyl)phenoxy]-ethanamine-HCl (DPPE), a tamoxifen derivate, inhibits the proliferation of HT168 cells. Furthermore, it is suggested that there is a factor(s) that interferes with the exponential growth of HT168 cells xenografted to immunodeficient mice, and cimetidine and DPPE together significantly influence this factor(s). This combination of antihistamines also increases the survival of human melanoma-grafted mice. These changes are accompanied by enhanced infiltration of interferon-gamma- producing mouse macrophages into the tumour tissue. These findings suggest that two different mechanisms are probably acting concordantly: direct inhibition of tumour cell proliferation by the H2 receptor antagonists, and activation of the local immune response characterized by interferon-gamma production. These findings may help to elucidate the possibility of a rationally designed antihistamine strategy in melanoma therapy.

Evidence for cell-mediated autoimmunity in patients with pemphigus vulgaris and bullous pemphigoid.

Lymphoid cells from 4 of 5 patients diagnosed as pemphigus vulgaris (PV) and 6 of 7 patients diagnosed as bullous pemphigoid (BP) demonstrated specific cell-mediated immunity by the production of migration inhibitory factor (MIF) in the presence of autologous epidermal saline extracts. Clinical treatment of these patients with immunosuppressive agents resulted in a state of unresponsiveness of their lymphoid cells to similar concentrations of the antigen. Controls consisted of lymphoid cells from patients with bullous burns or various drug allergies which failed to show significant MIF production in the presence of autologous skin extract. These studies suggest that both PV and BP patients posses cell-mediated immunity (CMI) to their own autologous tissue antigens and this CMI may play a role in the pathogenesis of these diseases.

Polymorphonuclear granulocyte chemotaxis and chemotactic factor generation by concanavalin A-stimulated peripheral blood mononuclear cells in patients with psoriasis.

Polymorphonuclear leukocytes from patients with psoriasis demonstrated a significantly enhanced chemotactic responsiveness to zymosan-activated human serum as compared to granulocytes from healthy volunteers. Furthermore, psoriatic peripheral blood mononuclear cells stimulated with concanavalin a produced an increased amount of lymphocyte derived chemotactic factor (LDCF) as compared to that in the case of healthy persons. The LDCF proved to be chemokinetic for the psoriatic granulocyte. It is postulated that these two phenomena may play a role in the pathogenesis of psoriasis.

Distinct subpopulations in HaCaT cells as revealed by the characteristics of intracellular calcium release induced by phosphoinositide-coupled agonists.

Intracellular calcium release induced by transient applications of phosphoinositide agonists was measured using adherent single HaCaT keratinocytes loaded with the acetoxymethyl derivative of fura-2. Application of ATP, bradykinin and formyl-Met-Leu-Phe (fMLP) resulted in a transient increase in intracellular calcium concentration ([Ca2+]i) with an average half-width of 40+/-21 s and a decay time constant of 15+/-10 s (mean +/- SD, n = 108), irrespective of the agonist applied. The cells could be classified into two groups: in 53% of the cells repeated stimulation brought about a progressively smaller change in [Ca2+]i (type 1 cells), whereas in the remaining cells the amplitude of the calcium transients was essentially unchanged (type 2 cells). Furthermore, calcium transients in type 1 cells had broader half-widths and slower decays. No difference was found between the agonists in respect of the characteristics of the evoked calcium transient within each subpopulation. However, bradykinin and fMLP desensitized some cells. These results indicate that the activation of the inositol trisphospate transduction pathway by different agonists induces a characteristic elevation of [Ca2+]i within a given cell. Our results demonstrate that cultured HaCaT keratinocytes are heterogeneous in respect of the calcium transients evoked by the activators of this second messenger system.

Prealbumin as a hapten carrier protein in certain varieties of dermatitis.

A significant decrease of serum prealbumin levels and an increased proportion of prealbumin bearing lymphocytes in peripheral blood have been found in patients of hapten-induced diseases. Prealbumin deposition in the vessel walls, and/or prealbumin positive cells (granulocytes, lymphocytes, macrophages) in the dermis have been observed in patients with proved drug allergy as well as allergic contact dermatitis using immunofluorescence technique. The eluates from membrane of lymphocytes of patients with drug allergy contained a mitogenic substance, probably antigen and sometimes prealbumin as well. These results also support the earlier suggested hypothesis that the prealbumin may act as a hapten carrier protein.

Supressor activity of peripheral blood mononuclear cells in patients with chronic discoid lupus erythematosus.

Significantly increased suppressor activity of peripheral blood mononuclear cells was demonstrated in patients suffering from chronic discoid lupus erythematosus.

UVB light and 17-beta-estradiol have different effects on the mRNA expression of Ro/SSA and La/SSB autoantigens in HaCaT cells.

Antibodies produced against the Ro/SSA and La/SSB autoantigens are not only of diagnostic value but they may even play a role in the pathogenesis of several autoimmune diseases (Sjögren's syndrome, subacute cutaneous lupus erythematosus, neonatal lupus erythematosus and systemic lupus erythematosus). Among other factors, ultraviolet (UV) radiation and also the hormonal milieu are well-known cofactors in the pathogenesis of these autoimmune diseases. The goal of our research was to study the possible alterations in mRNA levels of three different Ro antigens and that of two La species produced by alternative splicing in transformed human keratinocytes (HaCaT cells) after UVB irradiation and after 17-beta-estradiol treatment. The polymerase chain reaction technique was used to determine the mRNA levels of the Ro and La species after 24, 48, and 72 h of irradiation. The mRNA levels of calreticulin increased as a function of time after UV irradiation but the mRNA levels of 52 kDa and 60 kDa Ro mRNAs were unaltered. After treating the cells with 17-beta-estradiol, there was no change observed in the levels of Ro mRNAs or La exon 1 mRNA, but a gradual decrease was noted in the mRNA levels of La exon 1'. The importance of alterations in the ratio of La exon 1 to exon 1' is supported by the observations in patients with Sjögren's syndrome, and our results strengthen the notion that the Ro and La antigens participate in the pathogenesis of different autoimmune diseases.

Macrophage markers 25F9 and 27E10 on human keratinocytes in normal and diseased skin.

In the present study, an immunohistochemical analysis was made of the expression pattern of different macrophage markers such as 25F9, 27E10 and RM 3/1 on the surface of human keratinocytes (HK) in biopsies obtained from healthy volunteers and from patients with lichen planus, chronic cutaneous graft-versus-host reaction, mycosis fungoides, and purpura pigmentosa chronica. In biopsies from the healthy volunteers and from both clinically involved and uninvolved skin of the patients, the HK of the basal cell layer exhibited a specific peroxidase-positive reaction when the monoclonal antibody against 25F9 was used. Lesional HK from all patients studied displayed 25F9 and 27E10 in nearly the entire epidermis. The present findings provide further evidence that HK and macrophages share a number of common cell surface moieties.

Thrombospondin receptor (CD36) expression of human keratinocytes during wound healing in a SCID mouse/human skin repair model.

Using a human skin/severe combined immunodeficient (SCID) chimeric mouse model, we examined the keratinocyte expression of the thrombospondin receptor (CD36) and its ligand thrombospondin-1 (TSP1) in acute uninflamed wounds. Positive suprabasal keratinocyte expression of CD36 was observed as early as 30 minutes after wounding in the adjacent, intact epidermis; it disappeared 4 days later. Keratinocytes of the freshly re-epithelised wounds and those of the surrounding epidermis remained TSP1-negative throughout the whole observation period of 7 days. Our results indicate that CD36-positive keratinocytes, probably in connection with activated, TSP1-positive thrombocytes, may play an important role in the early phase of wound healing.

Subcorneal pustular dermatosis and IgA multiple myeloma.

A case of subcorneal pustular dermatosis associated with IgA multiple myeloma is described. The significance of the combination of the two diseases is not yet known, but the association is certainly more than coincidence.

Expression of monocyte/macrophage markers (CD13, CD14, CD68) on human keratinocytes in healthy and diseased skin.

The results of several investigations proved that, in special circumstances, human keratinocytes (HKs) synthesize and express cell surface moieties characteristic of effector and/or accessory cells of the immune system, such as CD16, CD36, HLA-DR, and intercellular adhesion molecule-1 (CD54), which are all detectable on the surfaces of macrophages. In the present study, skin biopsies from healthy volunteers, from positive tuberculin skin tests, and from patients with acute urticaria (AU), lichen planus (LP), psoriasis vulgaris (PV), mycosis fungoides (MF), and purpura pigmentosa chronica (PPC) were investigated by means of a multistep immunoperoxidase method to examine the reactivity of the HKs with a panel of monoclonal antibodies (MABs) characteristic of monocyte/macrophage cell lines. In biopsies obtained from positive tuberculin tests and from clinically involved skin of patients with LP, PV, MF, or PPC, a multifocal, positive peroxidase reaction was observed on the membranes of HKs of the basal and suprabasal cell layers when the MABs OKM13 (CD13), OKM14 (CD14), and Dako-Macrophage (CD68) were used. In contrast, specific staining of the HKs was not observed with the same antibodies in the biopsies of healthy volunteers or of patients with AU or in the uninvolved skin specimens obtained from the other patients. The HKs of PV, LP, MF, PPC, and AU patients and those of the healthy subjects all failed to give positive reactions when MABs against CD11b, CD15, or CD33 were used. The published data supplement the known surface characteristics of HKs, reflecting their stage of activation and differentiation.