[The role of bacterial superantigens in pathophysiology of the skin]

In contrast to conventional antigens, bacterial superantigens activate a large percentage of an organism's total T-cell repertoire. This has clinical implications particularly in the case of infections with Gram-positive bacteria. Unravelling the molecular mechanisms of superantigen-mediated T-cell activation has yielded new insights in the pathogenesis of a number of diseases, in the field of dermatology namely atopic dermatitis and psoriasis. Moreover, therapeutic applications of superantigens have begun to emerge.

Occupational protein contact dermatitis caused by meat and fish

BACKGROUND

Protein contact dermatitis is a form of contact dermatitis possibly triggered by proteinaceous allergens.

MATERIALS AND METHODS

We report two patients with a history of erythematous and urticarial skin reactions followed by transformation into prolonged papular symptoms upon contact with proteinaceous material.

RESULTS

The symptoms reported by the patients were reproducible by skin testing with meat (cow) and fish (salmon). Both patients experienced extracutaneous manifestations after ingestion of meat and fish, as proven by oral challenge. Specific immunoglobulin E (IgE) antibodies were detected in the patients' blood.

CONCLUSIONS

Both cases meet all major criteria of protein contact dermatitis, suggesting IgE-mediated immediate-type hypersensitivity with late-phase cutaneous reactions.

Identification of HLA-DR and -DQ alleles conferring susceptibility to pollen allergy and pollen associated food allergy

BACKGROUND

Allergenic crossreactivity of pollen and foods due to the antigeneic similarity of oligopeptides is a well established clinical phenomenon.

OBJECTIVE

To determine the immunopathological relevance of antigen presentation, we analysed the HLA class-II genotype of patients with either pollen allergy or pollen associated food allergy.

METHODS

One hundred and twenty patients with pollen allergy and 80 patients with pollen associated food allergy were evaluated by skin- prick tests, RAST, and HLA class-II genotyping. The control population comprised 4251 healthy blood and bone marrow donors.

RESULTS

Monovalent pollen allergy was observed in 57% (n=68) of patients with pollinosis (57x grass pollen, 11x birch pollen), but only in 15% (n=12) of patients with food allergy (9x grass pollen, 3x birch pollen). Hazelnut (71%), almond (65%), walnut (44%) and apple (41%) were the most common food allergens and frequently associated with birch pollen allergy. Grass pollen allergy was associated with an increased frequency of HLA-DQB1*0301 (RR=2.3; EF=0.4; P=0.0016) when compared with the control population. HLA-DRB *08 conferred a sixfold higher risk for peanut allergy (EF=0.3; P=0.0013) and -DRB1*12 a 13-fold higher risk for carrot allergy (EF=0.3; P<0.000001). The differences on allele frequencies detected among patients with food allergies diminished or turned statistically insignificant when their genotypes were directly compared to those of patients with the corresponding pollen allergies. This was found in the case of birch pollen associated hazel nut allergy for the extended haplotype HLA-DRB1*01, -DQA1*0101, -DQB1*0501 as well as in grass pollen associated peanut allergy for HLA-DRB1*08 (from RR=6, P=0.0013 to insignificant) and in birch pollen associated carrot allergy for HLA-DRB1*12 (from RR=13, P < 0.000001 to insignificant).

CONCLUSION

We were able to identify HLA class-II alleles associated with some allergies thus indicating that these alleles might confer susceptibility to the respective allergens. Similarities at the level of the HLA class-II genotype parallel the empirical finding of distinct cross-reactivity patterns thus complementing investigations of IgE specificities. Our observations provide evidence for the major importance of antigen presentation on the manifestation of distinct crossreactivity patterns.

[Psoriasis in the animal model]

Co-existing inflammation and epidermal hyperproliferation characteristic for psoriasis have been shown to be reproducible in several animal models utilizing a variety of different strategies. These models highlight some points of the multicausal pathogenesis of psoriasis. Based on observations made in the animal models, a hypothesis is proposed for the pathogenesis of psoriasis, the elements of which can be tested in a recently established xenogeneic transplantation model.

Superantigens but not mitogens are capable of inducing upregulation of E-selectin ligands on human T lymphocytes

Bacterial infections can exacerbate immune mediated dermatoses, possibly via superantigens produced by these bacteria. Therefore, we asked whether superantigens induce the expression of adhesion molecules which may then facilitate invasion of highly activated T cells into different organs. The influence of exfoliative toxin (ET) and toxic shock syndrome toxin-1 (TSST-1) stimulation on the expression of a broad panel of adhesion and costimulatory molecules was investigated by flow cytometry. We found that only the E-selectin ligands cutaneous lymphocyte-associated antigen (CLA) and sialylated Lewis(x) (CD15s) are significantly upregulated by these superantigens but not by mitogen stimulation. In contrast, the mucosal lymphocyte-associated antigen (MLA) recognized by the monoclonal antibody Ber-Act8 was not differentially induced by mitogen or superantigen stimulation. Therefore, T lymphocyte stimulation by bacterial superantigens might directly influence their skin homing capacity. Furthermore, the superantigen-driven induction of CD15s-an adhesion molecule which is absent or only weakly expressed by resting or mitogen stimulated T cells-may indicate a role of this antigen for T cell skin homing. An additional adhesion pathway via E-selectin may thus be available to lymphocytes, comparable to granulocytes which constitutively express CD15s.

[Nail polish allergy. An important differential diagnosis in contact dermatitis]

HISTORY AND CLINICAL FINDINGS

Case 1. A 34-year-old woman presented with a recurrent, itching and erythematous plaque on her right cheek. Case 2. A 27-year-old woman reported itching erythema on her fingertips from time to time recently. Inspection revealed dyshidrosiform blisters. Both patients had been using nail varnish and varnish remover. Case 3. A 49-year-old woman had, for about 5 years, repeatedly experienced itching erythema at the perionychium of several fingers on which she had placed artificial nails. Marked oedema and erythema was noted.

INVESTIGATION

Extensive epicutaneous tests were performed on these patients. They showed sensitisation against important allergens in nail varnish (toluolsulphonamide-formaldehyde resin), nail varnish remover (benzophenone-2) and artificial nails (ethylacrylate), respectively. The three patients also showed type IV sensitisation against other substances.

DIAGNOSIS, TREATMENT AND COURSE

Epicutaneous tests documented type IV allergies to important constituents of nail varnish, nail varnish remover and artificial nails. Symptoms and skin changes disappeared when these three items were no longer used.

CONCLUSION

Allergies against nail varnish and its remover and against artificial nails should be included in the differential diagnosis of skin allergies, even when patients have additional type IV sensitizations against common allergens. As the causative allergen can be easily avoided, knowledge of the particular problems associated with these allergies is of a great practical significance.

Leg ulcers in Klinefelter's syndrome--further evidence for an involvement of plasminogen activator inhibitor-1

An abnormality in platelet aggregability or fibrinolysis, namely elevated activity of plasminogen activator inhibitor-1 (PAI-1), has been recently documented in patients suffering from Klinefelter's syndrome associated with leg ulceration without underlying venous insufficiency. To determine whether increased PAI-1 activity is a general feature of Klinefelter's syndrome, or more specifically associated with leg ulceration, we investigated PAI-1 influencing parameters and PAI-1 activity in two groups of patients: (i) Klinefelter patients suffering from leg ulceration (n = 7); and (ii) Klinefelter patients without leg ulceration (n = 6). On analysing PAI-1 influencing parameters such as age, body mass index, triglycerides, C-reactive protein, testosterone, smoking behaviour, the presence of diabetes mellitus, and arterial hypertension, respectively, we found no statistically significant differences between the two groups. However, PAI-1 activity in group 1 was highly significantly elevated compared with that in group two patients (P < 0.005). We conclude that (i) PAI-1 activity is not elevated in Klinefelter's syndrome in general; (ii) elevation of PAI-1 activity in patients suffering from Klinefelter's syndrome does not appear to be secondary to PAI-1 influencing parameters; and (iii) elevation of PAI-1 activity may play a crucial role in the pathogenesis of leg ulceration in Klinefelter's syndrome. Therefore, a therapy for leg ulceration in Klinefelter's syndrome that aims to return the elevated PAI-1 activity to normal should be explored.

Alopecia areata but not androgenetic alopecia is characterized by a restricted and oligoclonal T-cell receptor-repertoire among infiltrating lymphocytes

Although the etiology of alopecia areata is still unknown, evidence has accumulated to support an autoimmune pathogenesis for this disease. To evaluate the role of T cells in alopecia areata the T-cell receptor VB-repertoire was investigated in lesional skin and blood of 5 patients by means of a semiquantitative technique based on the reverse transcriptase polymerase chain reaction. Three patients with androgenetic alopecia served as controls. Amplification products were screened for clonality by temperature gradient gel electrophoresis. Four of 5 patients with alopecia areata exhibited a lesional T-cell receptor-repertoire characterized by an almost exclusive utilization of variable regions beta 2, 4, and 13. Temperature gradient gel electrophoresis revealed the oligoclonal constitution of the infiltrate. The restricted nature of the lesional T-lymphocytic infiltrate in alopecia areata strongly suggests that an antigen-specific T-cell response plays an important role in the pathogenesis of this disease.

Induction of psoriasiform inflammation by a bacterial superantigen in the SCID-hu xenogeneic transplantation model

Psoriasis is a chronic skin disease affecting about 2% of the Caucasian population, characterized by co-existing inflammation and epidermal hyperproliferation. A T-lymphocyte-mediated autoimmune reaction induced by bacterial superantigens might be central in its pathogenesis. To model psoriasiform inflammation, we transplanted clinically uninvolved skin from psoriatic patients onto SCID mice. Repetitive intradermal injections with a bacterial superantigen and simultaneous intraperitoneal injections with the patients superantigen-stimulated peripheral mononuclear blood cells resulted in an inflammatory reaction exhibiting some of the hallmarks of psoriasis, e.g. epidermal hyperproliferation, papillomatosis, focal neo-expression of ICAMI, and an exocytotic T-lymphocytic infiltrate characterized by the expression of the cutaneous lymphocyte-associated antigen. These observations document the potential of superantigens to trigger psoriasiform dermatitis and provide a model to study lymphocyte homing.

Psoriasis and bacterial superantigens--formal or causal correlation?

Superantigens have recently been identified as candidates for triggering crucial events in the development of psoriasis. Seemingly contradictory observations may complement each other when discussed in the context of the concept of an effector cell cascade initiated by bacterial superantigens that eventually brings about disruption of peripheral tolerance of a CD8+ T-cell subset.

[Photodynamic therapy at the threshold of clinical use in disseminated dermatoses]

Photodynamic therapy (PDT) involving the sequential administration of photosensitizing drugs and light has a successful record in the treatment of superficial tumors. Recent investigations document not only cytotoxicity but also immunomodulatory effects of PDT. Cell type as well as state of activation and differentiation are among the parameters influencing susceptibility to PDT, thus allowing targeting of selected cell (sub-)populations. In addition to lasers, non-coherent light sources are also effective. These features, along with current clinical experience, suggest PDT as an interesting alternative to better established photochemotherapies in the treatment of widespread malignant and benign dermatoses.

Ethanol metabolite acetic acid as causative agent for type-1 hypersensitivity-like reactions to alcoholic beverages

BACKGROUND

Adverse reactions to alcoholic beverages are common and more frequently mediated by immunological mechanisms than previously thought.

OBJECTIVE

To elucidate relevant allergens in this context we studied patients with an informative medical history.

METHODS

This report describes a comprehensive allergological approach in a patient exhibiting type-I hypersensitivity-like reactions towards beverages and medication containing alcohol, and salad dressings with acetic acid.

RESULTS

The ethanol metabolite acetic acid was found to yield positive prick test results in concentrations not eliciting reactions in healthy and atopic controls.

CONCLUSIONS

Among other ethanol metabolites, acetic acid is a potential allergen in the context of hypersensitivity towards alcoholic beverages.

T-cell receptor beta variable region (V beta) usage in cutaneous T-cell lymphomas (CTCL) in comparison to normal and eczematous skin

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of lymphoproliferative disorders. We investigated the variable region (V beta) of the T-cell receptor (TCR) repertoire in CTCL and compared it to the V beta repertoire in normal and eczematous skin. We used a panel of 21 anti-V beta antibodies and investigated 84 biopsies of 71 CTCL patients (4 parapsoriasis en grandes plaques (PA), 1 lymphomatoid papulosis, 29 mycosis fungoides (MF), 13 Sezary syndrome (SS), 1 CD8+ CTCL, 11 pleomorphic CTCL (PLEO), 12 CTCL nor classified). Six biopsies of normal skin and 6 of eczematous skin lesions served as controls. We determined the frequency of the V beta in normal and inflamed skin and compared it to the percentage of the respective V beta in the malignant clone of the CTCL patients. The percentage of the V beta positive CD4+ cells in relation to the total number of T cells in normal skin and inflamed skin differed from the distribution of the V beta families in the peripheral blood mononuclear cells (PBMC). Out of 71 CTCL cases, the clone was identified in 23 (32%). We identified the following clones: 1 V beta 3.1 (16MF), 7 V beta 5.1 (1 CD8+ CTCL, 1 CTCL not classified, 1 MF, 1 PA, 3 SS), 1 V beta 6.7 (1 SS), 7 V beta 8.1/8.2 (2 CTCL not classified, 1 PLEO, 2 MF, 2 SS), 1 V beta 12.1 (1 PLEO), 3 V beta 17.1 (2 CTCL not classified, 1 MF), 2 V beta 22.1 (1 CTCL not classified, 1 MF), 1 TCR delta (SS). The frequency of the malignant clone V beta usage corresponded well to the repertoire of V beta in eczematous skin but not to the repertoire in PBMC. In 6 patients, the malignant clone was mainly localized in the epidermis. In 17 cases, the clone-specific cells were distributed in epidermis and dermis equally. A retrospective analysis showed that preferential epidermal homing of the clone was associated with a non-aggressive clinical course. The V beta usage of CTCL and eczema suggests a special cutaneous microenvironment which might be co-created by certain (bacterial?) superantigens. A preferential epidermal homing of the clone might have prognostic implications.

Tolerance to intravenous administration of heparin and heparinoid in a patient with delayed-type hypersensitivity to heparins and heparinoids

Delayed-type hypersensitivity reactions to subcutaneously (s.c.) injected heparins are common. Since similar reactions usually occur to different heparin preparations, semisynthetic heparinoids might be a therapeutic alternative. We report a patient exhibiting eczematous reactions to heparins as well as heparinoids; delayed-type hypersensitivity was demonstrated by intracutaneous (i.c.) and patch tests, as well as by s.c. provocation. Remarkably, intravenous (i.v.) administration of heparin as well as heparinoid was well-tolerated.

Familial juvenile onset psoriasis is associated with the human leukocyte antigen (HLA) class I side of the extended haplotype Cw6-B57-DRB1*0701-DQA1*0201-DQB1*0303: a population- and family-based study

To further evaluate the nature of the HLA association with psoriasis, HLA haplotypes of 60 patients with type 1 (early onset, positive family history) and 30 patients with type II (late onset, no family history) psoriasis were investigated by polymerase chain reaction sequence-specific oligonucleotide hybridization (HLA class II) and serology (HLA class I). Ethnically matched blood donors (146) served as controls. In type I, but not type II psoriasis, the Caucasian HLA extended haplotype (EH) Cw6-B57-DRB1*0701-DQA1*0201-DQB1*0303 named according to the B allele EH-57.1 was highly significantly overrepresented (p cor= 0.00021). This particular EH was present in 35% of type I psoriatics but only 2% of controls. EH-57.1+ individuals therefore carry a 26 times higher risk of developing type I psoriasis than individuals who are EH-57.1-negative Further analysis of individual HLA alleles revealed that within EH-57.1, HLA class I antigens (Cw6-B57) were associated to a much higher extent with type I psoriasis than the HLA class II alleles (DRB1*0701-DQA1*0201-DQB1* 0303). Pedigree analysis of three multiply affected families over three generations revealed a cosegregation of disease with EH-57.1. These results strongly suggest that a gene for familial psoriasis is associated with the class I side of the extended haplotype Cw6-B57-DRB1*0701-DQA1*0201-DQB1*0303.

Clinical and pathophysiological aspects of hydroxyethyl starch-induced pruritus: evaluation of 96 cases

BACKGROUND

It has been recently recognized that long-term infusions of hydroxyethyl starch (HES) as a substitute of human plasma may lead to deposits within the human skin and clinically induces severe pruritus in approximately one-third of the patients treated.

OBJECTIVE

To analyze the clinical features and pathophysiology of HES-induced itching.

METHODS

Clinical data of 86 patients were analyzed retrospectively. Furthermore, 10 patients were followed prospectively, in whom we also performed routine laboratory tests, skin biopsies, allergological investigations (skin prick, basophil degranulation test), and substance P measurements in stimulated macrophages.

RESULTS

Special features of HES-induced pruritus included long latency of onset and persistence. Noteworthy, itching is not always generalized. 30% of patients present with localized pruritus. Symptoms were not relieved by antihistaminics. Accordingly, the basophil degranulation test after HES exposure was negative. Also, substance P release from macrophages was not increased following HES stimulation. Deposits were found mainly in macrophages and endothelial cells.

CONCLUSIONS

Our findings indicate that pruritus in HES-infused patients is most likely not triggered by pruritogenic mediators. We support data from the recent literature, suggesting a direct stimulation of cutaneous nerves by HES deposits. In patients suffering from long-standing itching it seems important to consider previous HES exposure as a possible cause not only in generalized pruritus but also in localized symptoms.

The superantigen exfoliative toxin induces cutaneous lymphocyte-associated antigen expression in peripheral human T lymphocytes

Several immune-mediated dermatoses including psoriasis and atopic dermatitis can be exacerbated by bacterial infections. Superantigen producing bacteria can be isolated from skin lesions of these dermatoses. Consistent with superantigen effects, skewed T cell receptor variable gene usage has been demonstrated within these lesions. Therefore, the question arises whether superantigen induce a skin-seeking phenotype within peripheral T cells. In this study, we investigated the in vitro influence of the V beta 2-selective superantigen exfoliative toxin from Staphylococcus aureus on the expression of the cutaneous lymphocyte-associated antigen on peripheral T lymphocytes of healthy donors. We demonstrate that exfoliative toxin dramatically upregulates cutaneous lymphocyte-associated antigen expression on T cell receptor V beta 2+ lymphocytes. Up to 69% of V beta 2+ lymphocytes expressed cutaneous lymphocyte-associated antigen after 5 days of in vitro culture. Additionally, exfoliative toxin also increased cutaneous lymphocyte-associated antigen expression in CD3+ T cell receptor V beta 2- lymphocytes indicating a different effect as caused by the superantigen-T cell receptor V beta 2 interaction. Our findings suggest influence of bacterial superantigens on T lymphocyte skin homing in vivo.

Comparison of sensitivity towards photodynamic therapy of cutaneous resident and infiltrating cell types in vitro

BACKGROUND AND OBJECTIVE

Photodynamic therapy (PDT) combines photosensitizers absorbing light in the visible spectral region and irradiation with light of corresponding wavelengths. We analysed the sensitivity of cell lines established from resident cutaneous cells and from transformed lymphocytes towards PDT.

STUDY DESIGN/MATERIALS AND METHODS

PDT was performed employing either 630 or 662 nm light or polychromatic red light (600-700 nm) and photosensitizers Photosan-3, delta-aminolevulinic acid, or methylene blue. Proliferation measured by 3H-TdR uptake was determined in human immortalized keratinocytes (HaCaT) and mouse fibroblasts (NIH/3T3) in comparison to human transformed T-(HuT78) and B-lymphocytes (RA1). Additionally, uptake of the photosensitizers was estimated employing video-intensified fluorescence-microscopy (VIFM).

RESULTS

Depending on the photosensitizer tested HaCaT and NIH/3T3 exhibited an ED50 up to 10-fold as high as the lymphocytic lines. Polychromatic red light was at least as effective at inducing photodynamic reactions as 630 or 662 nm light. VIFM revealed a positive correlation between sensitivity of a given cell type towards PDT and uptake of the photosensitizers. The differential uptake observed in vitro was confirmed in vivo: A photosensitizer applied topically on a lesion of a patient with mycosis fungoides was found to accumulate preferentially in the lymphocytic infiltrate.

CONCLUSION

Selective topical polychromatic PDT seems to be a feasible goal for the treatment of cutaneous lymphomas.

Influence of activation and differentiation of cells on the effectiveness of photodynamic therapy

Photodynamic therapy combines photosensitizers absorbing light in the red spectral region and irradiation with light of the corresponding wavelength. To analyse the influence of cell differentiation on susceptibility to photodynamic therapy, we compared the proliferation inhibition induced by photodynamic therapy on normal human keratinocytes, spontaneously transformed human keratinocyte cell line HaCat and on squamous cell carcinoma lines. Cells were irradiated with polychromatic methylene blue as well as the precursor of protoporphyrin, 5-aminolevulinic acid. When incubated with Photosan-3, normal human keratinocytes exhibited and ED50 about 10-fold lower than the other cell lines studied. When methylene blue and 5-aminolevulinic acid were used, photodynamic therapy had comparable effects on all cell types. Stimulation of normal human keratinocytes with either EGF-alpha or IFN-gamma resulted in an increase susceptibility to photodynamic therapy when 5-aminolevulinic acid was used. This effect was more pronounced in the case of EGF-alpha. Our experiments suggest that activation and differentiation are two important parameters determining susceptibility to photodynamic therapy.

T-cell-receptor repertoire in chronic plaque-stage psoriasis is restricted and lacks enrichment of superantigen-associated V beta regions

Preferential usage of certain T-cell receptors by the lymphocytic infiltrate in psoriasis might indicate the involvement of an antigen in the pathogenesis of this disease. However, to date there are no data on the complete T-cell-receptor V alpha and V beta repertoire in psoriatic patients. We therefore compared the usage of T-cell-receptor variable regions in blood and skin of 10 patients with chronic plaque-stage psoriasis by means of semiquantitative polymerase chain reaction. Additionally, HLA class II alleles were analyzed by means of sequence-specific oligonucleotide typing. A considerable restriction of the T-cell-receptor repertoire was observed in the skin, where up to 20% of the variable regions present in the blood were not detectable. This was true for both alpha- and beta-chains. However, no interindividually constant pattern of T-cell-receptor restriction was deducible. Inconsistently, a certain preferential usage of some beta chains occurred within the cutaneous compartment. This report on the complete T-cell-receptor V alpha and V beta repertoire in psoriasis documents the restricted receptor repertoire of infiltrating T cells and a lack of enrichment of superantigen-associated V beta regions. Thus superantigens seem not to play a pathogenetically relevant role in chronic plaque-stage psoriasis.

A subset of macrophages located along the basement membrane ("lining cells") is a characteristic histopathological feature of psoriasis

In this paper, we describe the immunophenotype and ultrastructure of a new macrophage subpopulation present in inflamed but not in normal human skin. In biopsy material from patients with psoriasis (n = 4), atopic dermatitis (n = 4), and positive patch test reactions (n = 4), spindle-shaped macrophages located along the basement membrane were detected staining positive for CD11c (LeuM5 high, Ki-M1 low), CD68 (Ki-M6 low), and Ki-M8 (low). This subpopulation was most prominent in psoriasis, where a median of 34 macrophages neighbored 100 basal keratinocytes, thus covering about 80% of the dermoepidermal junction. The numbers of atopic and positive patch test reactions were 11 and 13, respectively, accounting for about 20% of the dermoepidermal junction. Transmission electron microscopy revealed an electron-lucent nucleus with dense deposits of chromatin along the nuclear membrane. Interruptions of the integrity of the basement membrane neighboring these cells were also seen. We repeatedly observed parts of basal keratinocytes merging through these openings and macrophages exhibiting cytoplasmic extentions directed toward the porus. Our observations suggest vigorous interactions between macrophages and basal keratinocytes and support the hypothesis that these interactions are an important regulatory event in the pathogenesis of psoriasis.

Differential expression of heat shock protein 70 (HSP70) and heat shock cognate protein 70 (HSC70) in human epidermis

Autoimmunity and microbial agents have been suggested as playing a pathogenetic role in psoriasis. Since immune responses to microbial infections are often directed towards heat shock proteins (HSP), we investigated the expression of three HSP families in normal and inflamed human skin. Specimens from ten patients with psoriasis and three patients with positive patch tests for nickel and from five healthy volunteers were analysed by means of immunohistochemistry. The patterns observed were qualitatively similar in these conditions showing only minor quantitative differences. Psoriatic epidermis exhibited the highest level of expression. HSP27, HSP70 and heat shock cognate protein 70 (HSC70) were readily detectable. HSP27 was homogeneously distributed throughout the epidermis, whereas HSP70 was restricted to the basal layer and HSC70 primarily to the suprabasal layers. Other HSPs were detected to a lesser degree and showed a more irregular pattern. Thus, the qualitative expression pattern of HSPs seems to be constant between different skin conditions, but the expression of constitutive and inducible HSP70 depends on the differentiation state of keratinocytes.

Primary subcutaneous leiomyosarcoma exhibiting the characteristic immunophenotype positive for vimentin and desmin

BACKGROUND

Primary subcutaneous leiomyosarcoma is a rare neoplasm composed of plump, elongated spindle cells arranged in interweaving fascicles.

OBJECTIVE

Differential diagnosis might be facilitated by the use of immunohistochemistry.

METHODS

A case of subcutaneous leiomyosarcoma was investigated histologically on paraffin-embedded tissue and immunohistochemistry was performed following standard procedures.

RESULTS

The case reported exhibited light microscopic features and an immunophenotype characteristic of leiomyosarcoma. However, the intermediate filament desmin could only be found on a small number of tumor cells.

CONCLUSION

Expression of these markers might vary considerably and immunoperoxidase stainings need to be carefully evaluated. Utilization of several antibodies directed against different desmin epitopes might be advantageous.

Analysis of TAP2 and HLA-DP gene polymorphism in psoriasis

TAP2 is a gene, located between HLA-DP and HLA-DQ, whose products form a transporter molecule involved in endogenous antigen processing. Polymorphic residues have been described in this gene. TAP2 is of particular interest because its involvement in antigen presentation makes it a candidate for a disease susceptibility gene. In psoriasis, two clinical subtypes analogous to the situation in diabetes type I with early onset and family history and type II with later onset and without family history have been described. We have previously shown that type I but not type II psoriasis is associated with the HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 haplotype. To investigate whether this haplotype extends to include particular TAP2 and/or DP alleles, we tested the TAP2 and HLA-DP alleles of a control group (n = 199), patients with psoriasis type I (n = 66), and patients with psoriasis type II (n = 35) by hybridization with SSOs. Our data show that there is no significant correlation between TAP2 and/or HLA-DP gene polymorphism and psoriasis type I and/or type II. We conclude that disease association in type I psoriasis is associated with the extended haplotype HLA-B57, -Cw6, -DRB1*0701/2, -DQA1*0201, -DQB1*0303.

Predominant usage of distinct T-cell receptor V beta regions by epidermotropic T cells in psoriasis

To investigate the role of T cells in psoriasis, we analyzed the T-cell receptor (TCR) repertoire in peripheral blood lymphocytes (PBLs) and in skin lesions of 9 patients with chronic plaque-stage psoriasis by means of immunohistochemistry. An extended panel of monoclonal antibodies detecting 11 different V beta families was employed in this study. In the peripheral blood, no predominant TCR V beta expression was detected and interindividual differences were small. Skin-infiltrating T cells showed only marginal differences in the TCR V beta usage when compared with PBLs. However, in 3 patients the intraepidermal infiltrate comprised up to 40% of T cells expressing a TCR V beta region which was virtually absent in the peripheral blood and the dermal infiltrate. Thus, although the TCR V beta usage of skin-infiltrating T cells showed little difference compared to PBLs, several cases exhibited a significant increase of epidermotrophic T cells using one particular V beta region.

Photodynamic therapy in psoriasis: suppression of cytokine production in vitro and recording of fluorescence modification during treatment in vivo

Photodynamic therapy (PDT) consists of the combination of photosensitizers absorbing light mainly in the red spectral region and irradiation with light of corresponding wavelengths. We analysed its effects on the cytokine secretion (IL-1 beta, TNF alpha, IL-6) of freshly isolated peripheral mononuclear cells from six patients with chronic plaque-stage psoriasis in comparison with PUVA. PUVA treatment resulted in a decreased production of all three cytokines, but most pronounced in the case of IL-6. PDT caused a similar change in the cytokine pattern, but its effectiveness was lower. In vivo fluorescence recordings were performed on psoriatic plaque lesions after topical application of the photosensitizer Photosan-3. Under irradiation, progressive photobleaching was noted with increasing radiation dosage. This is the first reported study of photochemical reactions using on-line fluorescence recordings during PDT of psoriatic lesions in vivo. Our results demonstrate the capacity of PDT to cause immunomodulatory effects similar to PUVA, thus indicating its potential application to the treatment of this common disease.

Psoriasiform architecture of murine epidermis overlying human psoriatic dermis transplanted onto SCID mice

Preliminary observations in a xenogeneic SCID mouse transplantation model indicated that murine epidermis overgrows human dermis from psoriatic skin but not that form normal skin. To investigate the effect of peripheral blood mononuclear cells on the differentiation of murine keratinocytes, we transplanted involved and uninvolved full-thickness skin from patients with psoriasis onto SCID mice and followed this with repeated subcutaneous injections of cells suspended in patient serum. After 6 weeks grafts were analysed morphologically and immunohistochemically. The epidermis in grafts from clinically uninvolved skin appeared normal. The persistence of a psoriasiform epidermis was noted in all grafts from affected sites despite a lack of lymphocytic infiltration. Staining for human and mouse MHC class I antigens revealed the murine origin of keratinocytes forming the psoriasiform epidermis, while the human dermis was retained. Our observations indicate that the defect underlying the pathogenesis of psoriasis is most likely located in the dermal rather than the epidermal compartment. This xenogeneic transplantation model may be useful for future studies of the pathogenesis and treatment of psoriasis.

In vitro and in vivo effects of photodynamic therapy in cutaneous T cell lymphoma

Photodynamic therapy consists of the combination of photosensitizers absorbing light in the visible spectral region and irradiation with light of corresponding wavelengths. We analysed its effects in comparison to PUVA treatment on cell lines MyLA and HuT78, established from patients with cutaneous T cell lymphomas. Proliferation was reduced to 50% by exposure to 7.5 J/cm2 UV-A (= ED50). This effect was increased more than 10-fold in the presence of 10 micrograms/ml 8-methoxypsoralen. The ED50 for photodynamic therapy using 630 nm light emitted by a dye laser and 10 micrograms/ml Photosan-3 was found to be about 1 J/cm2. In vivo fluorescence recordings during topical photodynamic therapy of mycosis fungoides lesions showed photo-bleaching and thus documented the triggering of photochemical reactions. Our observations document the capability of photodynamic therapy to inhibit proliferation of transformed T cells similar to PUVA, pointing out its potential in the treatment of cutaneous T cell lymphomas.

Clonal disease in early cutaneous T-cell lymphoma

Our experience with 185 cases of T-cell dominated skin infiltrates demonstrates that the PCR-based method for detection of TCR gamma chain gene rearrangement in combination with temperature gradient electrophoresis can routinely be used for the demonstration of clonal T cells in formalin-fixed and paraffin-embedded biopsies of lesional skin. In contrast to Southern blot analysis, the amplification by PCR is nonradioactive, is not time consuming (approximately 3 days), can be performed using frozen or paraffin-embedded tissue, and allows additional molecular biologic analyses, such as sequencing. Furthermore, it offers the possibility to design patient-specific primers for monitoring of the disease activity. It also has to be concluded from our study that all available clinical, histologic, cytologic, immunophenotypical, and rearrangement studies have to be considered in order to establish the correct diagnosis.

Evidence for a pathway independent from 2'-deoxyguanosine and reversible by IL-2 by which purine nucleoside phosphorylase inhibitors block T-cell proliferation

Patients with homozygous deficiency of purine nucleoside phosphorylase (PNP) present with a T-cell selective immune deficiency. To elucidate the potential use of PNP inhibitors in the therapy of cutaneous T-cell lymphomas (CTCLs) the authors studied the effects of CI-1000 (formerly PD141955-2) and CI-972 on a T-cell line MyLa established from a patient with mycosis fungoides. Both PNP inhibitors had significant, dose-dependent, inhibitory effects on the proliferation of the T-cell line. CI-1000 (ED50: 3.7 microM) was approximately six-fold more potent in blocking 3H-thymidine uptake than CI-972 (ED50: 22.5 microM). The inhibitory effect of either substance could not be increased by addition of deoxyguanosine. Flow cytometric analysis revealed that both PNP inhibitors caused a block in the S-phase of the cell cycle. The inhibitory effect on proliferation was reversible partially by addition of IL-2. When testing proliferation inhibition of both substances on an IL-2-dependent T-cell line (SeAx), their inhibitory effects were reduced significantly. These data document a mechanism of action of the PNP inhibitors independent of deoxyguanosine and partially reversible by IL-2. The authors' observations suggest the potential use of PNP inhibitors in the therapy of cutaneous T-cell lymphomas and provide evidence for a pathway independent from deoxyguanosine by which PNP inhibitors might function in T cells.

Discrimination between immunoaccessory and phagocytic monocytes/macrophages of the skin in paraffin-embedded tissue by the monoclonal antibody Ki-M1P

The variety of functions performed by monocytes and macrophages is reflected in their phenotypic diversity. Investigation of this complex system is facilitated by Ki-M1P, a new monoclonal antibody which recognizes a differentiation antigen on monocytes/macrophages in paraffin-embedded tissues. To test its usefulness as a pan-macrophage marker in the skin, we immunohistochemically analysed paraffin-embedded biopsy material from seven healthy individuals and 190 patients with a variety of dermatoses. Immunoreactivity was compared with results obtained with the antibodies KP-1, MAC-387, UCHL-1 and S-100. In normal skin, epidermal Langerhans cells were Ki-M1P-. Strong expression of this marker was detected on spindle-shaped as well as dendritic perivascular and intervascular macrophages. Pathological reaction forms such as giant cells and epithelioid cells in granulomatous dermatoses were also Ki-M1P+. The high specificity of Ki-M1P is reflected in the lack of reactivity with tumour cells in non-monocytic neoplasms and Langerhans cell histiocytosis. Thus, Ki-M1P is a useful marker for skin macrophages, discriminating between the immunoaccessory and the phagocytic compartments.

Oligonucleotide typing reveals association of type I psoriasis with the HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 extended haplotype

Although the pathogenesis of psoriasis is still a matter of debate, there are several lines of evidence supporting the concept of this disease being immunologically mediated with T cells playing a crucial role. Because a considerable portion of the cellular infiltrate in psoriasis consists of activated T-helper cells, expression of HLA class II antigens might be of particular importance for the understanding of its pathogenesis. Therefore, we investigated the HLA type of patients with type I (early onset, positive family history) and type II (late onset, no family history) psoriasis by means of serology (n = 89) and genotyping using sequence-specific oligonucleotide probes (n = 64). Serologic analysis of class I documented the association of type I psoriasis with HLA-Cw6, -B13, and -B57, whereas type II psoriasis showed a weaker correlation with HLA-Cw2 and -B27. Genotyping using SSO for class II detected the elevation of the HLA-DRB1*0701/2 allele frequency from 13% in normal population to 36% in type I, but only to 15% in type II psoriatics. Moreover, positive correlations with type I psoriasis were detected for HLA-DQA1*0201 and HLA-DQB1*0303. The HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 extended haplotype was found exclusively in type I psoriasis. This is the first report documenting the association of distinct HLA class II alleles with type I psoriasis as detected on the DNA level, an approach both more specific and more sensitive when compared to serology.

[Osteoma cutis. Multiple miliary osteoma of the face]

Primary and secondary forms of ossification can be distinguished on the basis of the skin, with osteoma cutis occurring in primary forms. Three entities can be differentiated: solitary and generalized osteoma cutis and multiple miliary osteoma of the face. Clinically, multiple papules 2-3 mm in diameter are present, which histologically consist of bony trabeculae enclosing mature fat cells and, occasionally, marrow cells. We describe the clinical, radiological and histological features of a case of multiple miliary osteoma of the face in an otherwise healthy 55-year-old woman.

The importance of dominant negative effects of amino acid side chain substitution in peptide-MHC molecule interactions and T cell recognition

Previous studies on the role of specific residues of the peptide or MHC molecule in Ag presentation have revealed the sensitivity of this complex system to even small changes in structure. In our study, we have analyzed the effect of amino acid substitution in a major CD4+ T cell determinant (T1) of HIV-1 gp160 on binding and recognition in the context of various E alpha E beta MHC class II molecules. Individual alanine substitutions at all but three positions had little or no negative effect on either MHC binding or recognition by a specific T hybridoma, whereas substitutions with larger side chains often diminished reactivity. A poly-alanine peptide containing only four of the original residues was an effective MHC class II binder and in vivo immunogen, although lacking the ability to stimulate the hybridoma. Replacement of a glutamic acid in T1 with alanine or a size-conservative, uncharged glutamine, but not a negatively charged aspartic acid produced a peptide at least 100-fold more potent than the parent peptide, indicating an inhibitory effect of the negative charge. Conversely, substitution of a glutamic acid for valine at position 29 in the floor of the peptide binding site of the E alpha E beta molecule decreased functional presentation of this peptide by more than 2 logs. However, these two effects of glutamic acid were not complementary and were mediated by distinct mechanisms, as the change in the peptide altered the extent of binding to class II, but the change in the MHC molecule decreased recognition without inhibiting peptide binding. Taken together, the data all suggest the conclusion that changes in side-chains of peptides and MHC molecules affect Ag presentation and T cell stimulation most often by introducing dominant negative or interfering groups that prevent or alter the pattern of binding events primarily mediated by a very limited number of other residues in the Ag or presenting molecule. These results have important implications for understanding the biochemistry of peptide-MHC-TCR interactions and for the possible design of vaccines both more potent and less subject to allele-specific limitations on immunogenicity.

The importance of dominant negative effects of amino acid side chain substitution in peptide-MHC molecule interactions and T cell recognition

Previous studies on the role of specific residues of the peptide or MHC molecule in Ag presentation have revealed the sensitivity of this complex system to even small changes in structure. In our study, we have analyzed the effect of amino acid substitution in a major CD4+ T cell determinant (T1) of HIV-1 gp160 on binding and recognition in the context of various E alpha E beta MHC class II molecules. Individual alanine substitutions at all but three positions had little or no negative effect on either MHC binding or recognition by a specific T hybridoma, whereas substitutions with larger side chains often diminished reactivity. A poly-alanine peptide containing only four of the original residues was an effective MHC class II binder and in vivo immunogen, although lacking the ability to stimulate the hybridoma. Replacement of a glutamic acid in T1 with alanine or a size-conservative, uncharged glutamine, but not a negatively charged aspartic acid produced a peptide at least 100-fold more potent than the parent peptide, indicating an inhibitory effect of the negative charge. Conversely, substitution of a glutamic acid for valine at position 29 in the floor of the peptide binding site of the E alpha E beta molecule decreased functional presentation of this peptide by more than 2 logs. However, these two effects of glutamic acid were not complementary and were mediated by distinct mechanisms, as the change in the peptide altered the extent of binding to class II, but the change in the MHC molecule decreased recognition without inhibiting peptide binding. Taken together, the data all suggest the conclusion that changes in side-chains of peptides and MHC molecules affect Ag presentation and T cell stimulation most often by introducing dominant negative or interfering groups that prevent or alter the pattern of binding events primarily mediated by a very limited number of other residues in the Ag or presenting molecule. These results have important implications for understanding the biochemistry of peptide-MHC-TCR interactions and for the possible design of vaccines both more potent and less subject to allele-specific limitations on immunogenicity.

A majority of proliferating T cells in cutaneous malignant T cell lymphomas may lack the high affinity IL-2 receptor (CD25)

IL-2 is a major growth factor for all T-cell subsets acting via a specific membrane receptor. To investigate its role in the pathogenesis of cutaneous T-cell lymphomas (CTCLs), we analysed the expression of high-affinity IL-2 receptors (IL-2Rs) on proliferating cells in these disorders. We showed by immunohistochemical double staining that most cycling cells do not express high-affinity IL-2Rs. Four T-cell lines were established from patients with CTCLs. Two lines required both IL-2 and IL-4 for growth, one line required IL-2 and one line IL-4 alone. The last of these lacked expression of the IL-2R alpha-chain. Thus, IL-2 may not be the only, or the most important, growth stimulus in CTCLs and reactive skin infiltrates. T helper cells, which dominated the infiltrate, might represent TH2 cells.

Role of beta 1-integrins in epidermotropism of malignant T cells

To better understand the molecular mechanisms of epidermotropism, we immunohistochemically analyzed the expression pattern of adhesion molecules belonging to the integrin and immunoglobulin superfamilies in cases of mycosis fungoides (MF) (n = 15), pleomorphic T cell lymphoma (n = 10), and high-grade T cell lymphoma (n = 7). The cutaneous T cell lymphomas (CTCLs) investigated were categorized into cases with or without epidermotropism. Focal neoexpression of ICAM-1 on keratinocytes was restricted to epidermotropic lymphomas. Both LFA-1 and LFA-3 were expressed on infiltrating cells in all cases investigated. In contrast, beta 1-integrins showed differential expression, most prominent in the case of VLA-1 and VLA-6: These molecules were present on infiltrating cells in most cases with epidermotropic MF and absent in most other CTCLs. We conclude that the phenomenon of epidermotropism might involve different sets of adhesion molecules in different entities of CTCL, with VLA-1 being the most influential beta 1-integrin in the case of MF.

Differential expression of adhesion molecules on infiltrating cells in inflammatory dermatoses

BACKGROUND

Adhesion molecules and their ligands are involved in coordination of the activities of the immune system.

OBJECTIVE

To evaluate whether adhesion molecules are relevant in the pathogenesis of inflammatory dermatoses, we analyzed the expression pattern of many of these molecules.

METHODS

The expression of 10 members of the integrin and immunoglobulin superfamilies was mapped by means of immunohistochemical techniques in biopsy specimens of psoriasis (n = 15), pityriasis lichenoides (n = 11), parapsoriasis en plaques (n = 11), contact dermatitis (n = 7), and lichen planus (n = 5).

RESULTS

In all investigated skin diseases, almost every infiltrating cell expressed lymphocyte function-associated antigens 1 and 3 as well as very late activation (VLA) antigens 4 and 5. The subepidermal infiltrate differed with regard to the expression of VLA-1, VLA-3, and VLA-6, which was high in lichen planus and moderate or absent in the other dermatoses. The intraepidermal lymphocytes in psoriasis and pityriasis lichenoides were VLA-1 positive, whereas the subepidermal infiltrate lacked this marker.

CONCLUSION

The differential upregulation of adhesion molecules in the mononuclear infiltrate and on keratinocytes demonstrates their importance in the pathogenesis of cutaneous inflammation.

Demonstration of clonal disease in early mycosis fungoides

Cutaneous T-cell lymphomas (CTCLs) are known to show monoclonal T-cell infiltrates late in the course of the disease. However, detection of monoclonal T-cell proliferation in early stages is difficult. To investigate the possibility that clones might appear only as minor subpopulations, we analyzed the proliferative activity of T cells expression certain variable (V) regions of the T-cell receptor (TCR). In biopsy specimens from 27 patients with CTCLs, all T cells expressing the V regions V alpha 2, V beta 5a, V beta 5b, V beta 6, V beta 8 and V beta 12 accounted for less than 5% of the total infiltrate. In the vast majority of the cases, less than 3% of the cells expression one TCR V region proliferated. In one case of mycosis fungoides, however, an epidermotropic clone expressing V beta 8 was detected. This clone was present in two distinct lesions from different anatomic sites and was found in an early relapse 1 year after complete remission following PUVA therapy. The case described here documents the possibility of clonal disease early in the course of mycosis fungoides.