Retinoid signaling by all-trans retinoic acid and all-trans retinoyl-beta-D-glucuronide is attenuated by simultaneous exposure of human keratinocytes to retinol

Retinol and retinyl esters are converted with time to slowly increasing amounts of all-trans retinoic acid (RA) in cultured human keratinocytes. Exogenous RA has been shown to limit retinol oxidation and to increase retinol esterification. Because significant amounts of retinol are present in biologic systems, we examined whether RA and all-trans-retinoyl-beta-D-glucuronide (RAG) interact with retinol in exhibiting their activities on HaCaT keratinocytes maintained in a retinoid-free culture system. RA was more potent than RAG and retinol in inducing ultrastructural changes attributed to retinoids, inhibiting cell proliferation as well as enhancing keratin 19 expression. In addition, retinoids were able to induce cellular retinoic acid-binding protein II mRNA levels in the cultures, whereas early RA and late RAG activity was detected. The described biologic effects of RA and RAG were diminished by simultaneous cell exposure to retinol. HaCaT cells quickly metabolized retinol to retinyl esters and consequently to low amounts of RA. RA treatment led to an early high peak of cellular RA followed by reduction to trace amounts. Treatment with RAG resulted in constantly high cellular RAG and low RA levels. Under the combined RA and retinol treatment retinyl esters were increased and RA was reduced in HaCaT cells, whereas extracellular RA levels were similar to those obtained by RA alone. On the other hand, the combination of RAG and retinol resulted in higher extracellular RAG, similar cellular RAG, and lower cellular RA levels than those obtained by RAG alone without any change in retinyl esters. This study demonstrates that retinoid signaling by RA and RAG is attenuated by simultaneous exposure of HaCaT keratinocytes in vitro to retinol. The presence of retinol in the medium alters the rate of RA or RAG metabolism and thus cellular RA concentrations. The intensity of retinoid signal is probably dependent on cellular RA levels. The resulting "antagonism" among retinoids is consistent with the presence of an auto-regulatory mechanism in human keratinocytes offering protection against excessive accumulation of cellular RA.

Desensitization of melanoma cells to autocrine TGF-beta isoforms

Previous studies have suggested that transforming growth factor-beta 1 (TGF-beta1) acts as an autocrine growth inhibitor on normal human melanocytes, while melanoma cells may not respond to this stimulus. The role of other TGF-beta isoforms such as TGF-beta2 and TGF-beta3 remained less well characterized. In the present study, the mRNA and protein levels of all three isoforms of TGF-beta were analyzed in a panel of human melanoma cell lines and in cultures of normal human melanocytes in vitro. Northern analysis showed that the degree of TGF-beta1, -beta2, -beta3 mRNA expression varied considerably in melanoma cells, whereas TGF-beta expression was very low in melanocytes. In melanoma cells, secreted amounts of TGF-beta1 and TGF-beta3 were found increased in comparison to normal melanocytes: 615 pg/ml vs. 118 pg/ml and 193 pg/ml vs. 30 pg/ml (mean values). In addition, low levels of TGF-beta2 were detected (mean value: 28 pg/ml). Although TGF-beta secretion increased, the proliferation of melanoma cells was found to be only moderately inhibited by TGF-beta isoforms, in contrast to its strong antiproliferative effect on normal human melanocytes: - 15%, -11%, and -18% vs. -52%, -46%, and -50% average inhibition at 0.5 ng/ml TGF-beta1, -beta2, and -beta3, respectively. The different efficacy of TGF-beta on melanocyte and melanoma cells was highly significant (P<0.0001); in addition, TGF-beta-dependent growth inhibition of melanoma cells from primary tumors vs. cells from metastases showed a trend for further decreased response for the metastatic populations (P< or = 0.075). Measurements of DNA synthesis revealed even more pronounced differences between melanocytes (-86%, -78%, and -80% inhibition, respectively, for TGF-beta1, -beta2, and -beta3) and melanoma cells (no inhibition). Our data show loss of responsiveness of melanoma cells to the growth-inhibitory function of TGF-beta isoforms but not of melanocytes. Although melanoma cells are not growth-inhibited by all three TGF-beta isoforms, they secrete significantly higher levels of TGF-beta, as compared to melanocytes. The reduced response indicates their escape from TGF-beta surveillance with ongoing tumor progression.

[Pseudo-scabies transmitted by red fox]

Pseudoscabies, i.e. infestation of human skin with animal mites may occasionally occur and should be considered in the differential diagnosis of pruritic and papular skin disease. We report here on a 52-year-old woman with pseudoscabies or canine scabies (Sarcoptes scabiei var. canis), transmitted by indirect contact with a red fox in the urban area of Berlin. Red foxes may live in unhabited areas of metropolitan large cities, i.e. in garages, car wrecks and cellars. Full remission of the prolonged and pruritic rush was seen after topical administration of lindane together with systemic corticosteroids.

Induction of apoptosis by synthetic ceramide analogues in the human keratinocyte cell line HaCaT

In contrast to extracellular, long chain ceramides which comprise a structural component of the epidermal water barrier, intracellular ceramides originating from sphingomyelin hydrolysis have been shown to inhibit proliferation and to induce apoptosis in different cell populations. To further elucidate the possible role of intracellular ceramides in human epidermis, two new cell-permeable ceramide analogues, N-thioacetylsphingosine (C2-Cer=S) and 4-dodecanoylamino-decan-5-ol (FS-5), were synthesized and tested for their ability to suppress cell growth and to induce apoptosis in immortalized human keratinocytes. It was shown that the well-investigated ceramide analogue N-acetylsphingosine (C2-Cer=O), as well as the new compound C2-Cer=S inhibited proliferation of HaCaT cells with half-inhibitory concentrations (IC50) of 20 microg/ml and 10 microg/ml, respectively, whereas FS-5 has been potent with an IC50>40 microg/ml. Overall, all three ceramide analogues induced apoptosis in HaCaT cells as assessed by DNA-fragmentation using ELISA technique and in situ nick end labelling, thereby confirming the importance of ceramide signalling in keratinocytes.

Expression of vascular endothelial growth factor (VEGF) in various compartments of the human hair follicle

Hair follicle vascularization appears to be closely related to the processes involved in hair cycle regulation, in which growth factors, cytokines and other bioactive molecules are involved. In particular, vascular endothelial growth factor (VEGF), essential for angiogenesis and vascular permeability, may be responsible for maintaining proper vasculature around the hair follicle during the anagen growth phase. The aim of our study was to compare the in vitro angiogenic capacity, i.e. the steady-state expression of the VEGF gene, of different cultured cell types derived from normal human hair follicles, corresponding to different follicular compartments. Human dermal papilla cells (DPC), fibrous sheath fibroblasts, dermal fibroblasts, and follicular and interfollicular keratinocytes were cultured and studied in vitro for VEGF expression at the mRNA level using RT-PCR, and for VEGF protein synthesis by radioimmunoprecipitation and immunocytochemistry. In vivo examination for VEGF expression in human terminal hair follicles was performed using immunohistochemical methods. In the present report the expression of four different VEGF molecular isoforms, differing in their angiogenic capacity, are described in different cultured follicular cell types for the first time. Cultured follicular cells strongly expressed mRNA of four VEGF molecular species identified as the 121-, 145-, 165- and 189-amino acid splice variants, the most prominent being the 121-amino acid molecule. DPC, and also other mesenchymal cells such as fibrous sheath fibroblasts and dermal fibroblasts, in vivo and in vitro strongly expressed VEGF mRNA and synthesized a 46-kDa VEGF protein, whereas follicular and interfollicular keratinocytes in vitro expressed lower levels of VEGF mRNA and proteins than mesenchymal cells. As the highest expression of VEGF was found in DPC, we suggest that DPC are mainly responsible for angiogenic processes possibly related to the human hair cycle.

Progressive HHV-8-positive classic Kaposi's sarcoma: rapid response to interferon alpha-2a but persistence of HHV-8 DNA sequences in lesional skin

The pathogenesis of Kaposi's sarcoma (KS) is often attributed to an infectious agent. In particular, the human herpesvirus 8 (HHV-8) was currently shown to be closely related to all known KS types, including HIV-associated KS, European classic KS, African endemic KS and iatrogenic KS. We report here on an HIV-negative, German patient of neither Jewish nor Mediterranean descent with disseminated classic KS showing unusual rapid progression into the tumour stage. After systemic administration of interferon alpha-2a over 4 weeks all tumour lesions cleared completely. Interestingly, HHV-8 DNA sequences detected by nested polymerase chain reaction in KS lesions before the onset of treatment were still present in lesional skin after complete remission of the tumour. No recurrence was seen after a follow-up period of 6 months.

Langerhans cells do not express alternative macrophage activation-associated CC chemokine (AMAC)-1

We have cloned a novel human CC chemokine, alternative macrophage activation-associated CC chemokine (AMAC)-1 that is highly homologous to macrophage inflammatory protein (MIP)-1alpha. In contrast to MIP-1alpha, AMAC-1 is induced in macrophages by Th2-associated cytokines IL4, IL13, and IL10 in vitro; in addition, AMAC-1 is expressed by Th1-suppressive alveolar macrophages in vivo. Surprisingly, however, AMAC-1 is also expressed by GM-CSF-induced, in vitro monocyte-derived dendritic cells when treated by IL4. Here, we present a detailed analysis of AMAC-1 expression in monocyte-derived dendritic cells in vitro and show that the prime dendritic cells in vivo, i.e. epidermal Langerhans cells, do not express AMAC-1 mRNA. In conclusion, AMAC-1 is a novel CC chemokine whose Th2-associated expression pattern in alternatively activated suppressor macrophages in vivo and in vitro and its absence from epidermal Langerhans cells in vivo suggest that it may be involved in inhibition of Th1 reactions and in tolerance induction.

Treatment of Adamantiades-Behçet disease with systemic interferon alfa

OBJECTIVE

To evaluate the efficacy and safety of systemic interferon alfa treatment in patients with Adamantiades-Behçet disease.

DATA SOURCES

Reports and abstracts published in 1986 through 1997 in all languages were identified by the MEDLINE database, the Reference Index Related to Behcet's Disease, the Behçet disease conference proceedings, and abstract booklets. The indexing terms used Behçet and interferon.

STUDY SELECTION

Twenty-two reports identified were included to estimate the efficacy of interferon alfa on mucocutaneous, ocular, and joint manifestations. Responses of individual mucocutaneous signs were evaluated in 8 reports. Adverse effects were sufficiently documented in 12 reports. All patients met the criteria of the Behçet Syndrome Research Committee of Japan or those of the International Study Group for Behçet's Disease.

DATA EXTRACTION

Data were extracted and evaluated according to the following criteria: complete remission, disappearance of all manifestations during treatment; partial remission, greater than 50% decrease in the number, severity, duration and/or frequency of recurrence of the lesions; stable disease, less than 50% change in the manifestations; and progressive disease, greater than 50% deterioration of existing manifestations or/and the development of new ones.

DATA SYNTHESIS

Systemic interferon alfa has been administered in 144 patients with Adamantiades-Behçet disease by subcutaneous or intramuscular injections of 3 to 18 x 10(6) units of interferon alfa-2a (70 patients) or 3 to 5 x 10(6) units of interferon alfa-2b (74 patients) daily or 3 times per week for 1 to 60 months. Seventy-four percent (92/124) of patients with mucocutaneous manifestations, 95% (37/39) of patients with uveitis, and 93% (51/55) of patients with arthropathy/arthritis exhibited a partial or complete response. Interferon alfa-2a regimens were more effective than interferon alfa-2b ones on mucocutaneous (47% vs 7% complete response) and ocular (67% vs 8% complete response; P < .001) manifestations. Mucocutaneous and ocular manifestations responded within 1 to 4 months after initiation of therapy. Thirty-eight percent (20/52) of patients with mucocutaneous lesions, 73% (8/11) of patients with uveitis, and 88% (21/24) of patients with arthropathy/arthritis experienced recurrences immediately or up to 7 months after discontinuation of treatment. Mild adverse effects were generally recorded; transient influenza-like symptoms (87% vs 63%; P < .05) and reversible leukopenia (24% vs 4%; P < .05) occurred more often under interferon alfa-2a regimens, while reversible mild alopecia was more common in patients receiving interferon alfa-2b (2% vs 28%; P < .01).

CONCLUSIONS

Systemic interferon alfa treatment is reasonable for Adamantiades-Behçet disease. A 3-month high-dose regimen (9 x 10(6) units 3 times per week) followed by a low maintenance dose (3 x 10(6) units 3 times per week) is recommended.

Pseudotumour of the tongue caused by herpes simplex virus type 2 in an HIV-1 infected immunosuppressed patient

An HIV-1 infected immunosuppressed patient (CD4+ cell counts: 382 cells/microL; viral load 94,000 copies/mL) with recurrent perianal herpes simplex virus type 2 (HSV-2) infections is described, showing an unusual exophytic tumour resembling a squamous cell carcinoma in the lateral part of the tongue. He also had persistent facial herpes infection, oral candidosis, oral hairy leukoplakia and lymphadenopathy. The presence of HSV-2 was detected by polymerase chain reaction both in smears and in a tissue biopsy taken from the involved tongue area. Treatment with brivudin, a new oral virustatic drug, led to rapid regression of the tumour.

[Acute generalized exanthematous pustulosis, induced by nystatin]

Despite its widespread use, the antimycotic nystatin rarely causes allergic reactions. We observed a case of acute generalized pustular exanthem with arthralgia and fever, after the oral administration of nystatin. A causal relationship was demonstrated by positive Intracutaneous testing of the drug. Immunohistology revealed positive staining for C3 in the test area, whereas circulating immune complexes could not be identified. These findings are compatible with a type-II allergic reaction. Systemic prednisolone treatment led to a complete remission of the clinical symptoms within 11 days. In two test subjects who had never received nystatin intracutaneous testing was initially negative. After 3 weeks, both developed itching erythematous papules at the injection sites. Therefore, intracutaneous testing of nystatin involves the risk of sensitization.

Elevated plasma levels of transforming growth factor (TGF)-beta1 and TGF-beta2 in patients with disseminated malignant melanoma

Overexpression of transforming growth factor-beta isoforms (TGF-beta1, -beta2, -beta3) has been previously reported in human melanoma cell lines and tumours. The aim of the present study was to evaluate the plasma levels of TGF-beta isoforms in melanoma patients. Significantly elevated levels of TGF-beta1 (4.2 x the controls, P = 0.0094) and of TGF-beta2 (1.5 x the controls, P = 0.012) but not of TGF-beta3 were measured in patients with disseminated but not locoregional melanoma. These results indicate systemic circulation of potentially immunosuppressive peptides of the TGF-beta family in end-stage melanoma patients.

Elevated plasma levels of transforming growth factor (TGF)-beta1 and TGF-beta2 in patients with disseminated malignant melanoma

Overexpression of transforming growth factor-beta isoforms (TGF-beta1, -beta2, -beta3) has been previously reported in human melanoma cell lines and tumours. The aim of the present study was to evaluate the plasma levels of TGF-beta isoforms in melanoma patients. Significantly elevated levels of TGF-beta1 (4.2 x the controls, P = 0.0094) and of TGF-beta2 (1.5 x the controls, P = 0.012) but not of TGF-beta3 were measured in patients with disseminated but not locoregional melanoma. These results indicate systemic circulation of potentially immunosuppressive peptides of the TGF-beta family in end-stage melanoma patients.

Induction of ceramide-mediated apoptosis by the anticancer phospholipid analog, hexadecylphosphocholine

The prototype of a new class of antiproliferative phospholipid analogs, hexadecylphosphocholine (HePC), has been shown to inhibit tumor growth and is currently used for the treatment of cutaneous metastases of mammary carcinomas. Although several cellular targets of HePC, e.g. protein kinase C and CTP:phosphocholine cytidylyltransferase, have been proposed, the mechanisms of HePC-induced anticancer activity are still unclear. Considering that the antiproliferative effect of HePC correlates with inhibition of phosphatidylcholine biosynthesis, which is tightly coupled to sphingomyelin biosynthesis, we tested the hypothesis that treatment of cells with the anticancer drug leads to increased cellular ceramide and subsequently to apoptotic cell death. In the present study, we showed that 25 micromol/liter HePC induced apoptosis. In further experiments, we demonstrated that HePC inhibited the incorporation of radiolabeled choline into phosphatidylcholine and at a later time point into sphingomyelin. This was confirmed by metabolic labeling of the lipid backbone using radiolabeled serine, and it was shown that HePC decreased the incorporation of serine into sphingomyelin by 35% and simultaneously increased the incorporation of serine into ceramide by 70%. Determination of the amount of ceramide revealed an increase of 53% in HePC-treated cells compared with controls. In accordance with the hypothesis that elevated ceramide levels may be the missing link between the metabolic effects of HePC and its proapoptotic properties, HePC-induced apoptosis was blocked by fumonisin B1, an inhibitor of ceramide synthesis. Furthermore, we found that membrane-permeable ceramides additively increased the apoptotic effect of HePC.

Expression and regulation of phospholipase D in the human keratinocyte cell line HaCaT

The generation of lipid second messengers via phosphatidylcholine (PC)-specific phospholipase D (PLD) has emerged as an important step leading to transduction of extracellular signals. In the present investigation the expression of human cytosolic PLD isoenzymes in the immortalized human keratinocyte cell line HaCat was determined. At the mRNA level we found the expression of hPLD1b and for the first time in human cells also the expression of hPLD2. For further analysis of enzyme expression at the protein level, hPLD1 peptide fragments were synthesized and specific antibodies were generated (rabbit) to be used for detection of hPLD1 in Western blot experiments. Furthermore, small G-proteins were found to be involved in the regulation of PLD activity in HaCaT cells using the guanine nucleotide analogue GTPgammaS.

[HIV-associated psoriasis. Clinical and histological observations in 36 patients]

Between 1982 and 1995, over 700 HIV-infected patients with different skin diseases were registered at the Department of Dermatology, Benjamin Franklin Medical Center, The Free University of Berlin. Thirty-six of them (approximately 5%) were diagnosed as having psoriasis. This is clearly a higher prevalence of psoriasis than in the general population (1-2%). If psoriasis lesions are not clinically seen before diagnosis of HIV infection, the disease will preferentially (approximately 80% of these cases) appear during the late stages of the infection (CD4/CD8 ratio < 0.4). Six of the 36 patients with HIV-related psoriasis (= 16%) were found to have severe disease, showing an exsudative clinical picture. In this paper we report in detail on two representative cases from this group of patients. Histological examination also revealed exsudative changes in HIV-infected patients with clinically moderate psoriasis. Immunohistochemically, HIV-related psoriasis showed a moderately decreased number of infiltrating T-cells, in contrast to psoriatic skin from non-infected patients. A marked difference was the reduced expression of the lymphocyte antigen OPD-4 in HIV-related psoriasis. Routine antipsoriatic treatment modalities in combination with systemic retinoids and phototherapy (SUP/PUVA) were successful in the treatment of severe exsudative psoriasis in HIV patients, but the course of the disease was prolonged and exacerbation was more frequent. HIV-related psoriasis was found not to influence the underlying HIV infection.

RT-PCR for tyrosinase-mRNA-positive cells in peripheral blood: evaluation strategy and correlation with known prognostic markers in 123 melanoma patients

Reverse transcriptase polymerase chain reaction for the detection of tyrosinase-mRNA-positive cells in peripheral blood of melanoma patients, as a possible marker of hematogenous dissemination, has demonstrated varying detection rates. This study examined the sensitivity and reproducibility of the technique using a protocol of multiple polymerase chain reaction to determine circulating melanocytic cells. For each of the 123 melanoma patients included in this study, four nested polymerase chain reactions were performed from two blood specimens requiring both polymerase chain reactions from at least one blood sample to be positive to consider a patient as positive. Thus, a definitive result was obtained in 98% of the cases, whereas only 1.6% lacked conclusive findings. Thus, we found a correlation between the tyrosinase detection rate and the clinical stage. Circulating tyrosinase-mRNA-positive cells were detected in 13% of patients with primary tumor, 17% with regional skin/lymph node metastasis, and 44% with distant metastasis. Positivity also correlated with known melanoma progression markers such as gender, tumor thickness, and histologic type. Positive results were obtained more frequently in (i) men compared with women, (ii) patients with thick primary melanomas (> 4 mm: 38%) compared with those with thinner tumors (1.1-4 mm, 22%; < or = 1 mm, 5%), and (iii) patients with nonclassifiable (38%), nodular (34%), and occult primary melanomas (30%) compared with those with acrolentiginous (17%), superficial spreading (9%), or lentigo maligna melanoma (0%). These findings suggest that detection of tyrosinase-mRNA-positive cells in peripheral blood is not an adequate marker for identifying melanoma patients with distant metastasis. Reverse transcriptase polymerase chain positivity in early melanoma stages, however, as corresponding to other prognostic parameters, may indicate increased risk for the development of hematogenous metastasis and may be of value as a progression marker.

Alternative macrophage activation-associated CC-chemokine-1, a novel structural homologue of macrophage inflammatory protein-1 alpha with a Th2-associated expression pattern

We have cloned a novel human CC-chemokine, alternative macrophage activation-associated CC-chemokine (AMAC)-1. The isolated cDNA clone (803 bp) shows a single open reading frame of 267-bp coding for 89 amino acid residues; mature AMAC-1 protein is predicted to consist of 69 amino acids with a m.w. of 7855. Sequence alignment and 3D-modeling show the typical structural characteristics of CC-chemokines with special features in the receptor-activating domain. AMAC-1 is most closely related to MIP-1 alpha with a cDNA and protein sequence homology of 55% and 59%, respectively. However, the expression pattern of AMAC-1 is directly opposite to that of MIP-1 alpha. While MIP-1 alpha is induced by classical macrophage mediators such as LPS and is inhibited by IL-4 and glucocorticoids, AMAC-1 is specifically induced in macrophages by alternative macrophage mediators such as IL-4, IL-13, and IL-10. Expression of AMAC-1 is inhibited by IFN-gamma while glucocorticoids exert a slightly positive synergistic effect in combination with IL-4. Peripheral blood monocytes do not express AMAC-1; time course experiments show that monocyte-to-macrophage differentiation is a prerequisite for AMAC-1 expression. Expression of AMAC-1 by granulocyte-macrophage CSF/IL-4-induced, monocyte-derived dendritic cells is complex; in mature adherent dendritic cells, however, only minor AMAC-1 mRNA expression was found. In vivo, AMAC-1 is expressed by alveolar macrophages from healthy persons, smokers, and asthmatic patients. In conclusion, AMAC-1 is a novel CC-chemokine whose expression is induced in alternatively activated macrophages by Th2-associated cytokines; thus, AMAC-1 may be involved in the APC-dependent T cell development in inflammatory and immune reactions.

Evidence of heterogeneity and quantitative differences of the type 1 5alpha-reductase expression in cultured human skin cells--evidence of its presence in melanocytes

Steroid 5alpha-reductase is of crucial importance in androgen physiology because it catalyzes the conversion of testosterone into the more potent 5alpha-dihydrotestosterone in androgen-regulated target tissues. The enzyme occurs in two isoforms, whereby type 1 isozyme exists mainly in the skin and type 2 in the prostate. By using human cell cultures, we examined cutaneous expression and subcellular localization of type 1 5alpha-reductase in vitro. In immunocytochemistry, type 1 5alpha-reductase was detected in the cytoplasm of cultured human sebocytes, keratinocytes, fibroblasts, dermal microvascular endothelial cells, hair dermal papilla cells, and melanocytes. In western blot studies, two closely lying bands of 21-27 kDa were detected, possibly indicating heterogeneity of the type 1 5alpha-reductase in all the cell types tested, with the exception of beard dermal papilla cells. Northern blot studies revealed most abundant type 1 mRNA in neonatal foreskin keratinocytes, followed by adult facial sebocytes. Occipital hair dermal papilla cells presented higher levels of type 1 5alpha-reductase mRNA than those of beard. These findings were confirmed by semiquantitative reverse transcriptase polymerase chain reaction coupled with high performance liquid chromatography analysis. Taken together, it seems likely that in cultured human skin cells there exist (i) heterogeneity of type 1 5alpha-reductase protein and (ii) quantitative differences in its transcriptional and translational expression levels.

Epidemiological features of Adamantiades-Behçet's disease in Germany and in Europe

The German Registry of Adamantiades-Behçet's disease was founded in 1990 in Berlin and it provides current data on the epidemiology, the clinical manifestations and the course of the disease in Germany on a continuous basis. A total of 218 patients, including 89 German and 100 Turkish patients, had been reported to the German Registry until October 1997. One hundred and ninety-six patients fulfilled the criteria of the Behçet's disease classification tree. The prevalence of the disease evaluated in Berlin-West was 1.68/100,000 in 1989 and had risen to 2.26/100,000 by 1994. The median age of onset was 25 years (range 5 to 66 years; German-Turks, ns). Juvenile disease was recorded in 6.9% of patients. The complete clinical picture according to the criteria of the International Study Group of Behçet's Disease developed in 15.5 months. The interval between onset of the disease and diagnosis was 35 months, which was significantly longer than the duration of the development of the complete clinical picture (p < 0.0001). The disease was diagnosed later in German (48.5 months) than in Turkish patients (25.5 months, p = 0.003). While German patients presented an equal male-to-female ratio, a male predominance was shown in Turkish patients (M:F 2.1:1, p = 0.022). Familial occurrence was detected in 2.0% of German and 15.9% of Turkish patients (p = 0.013). The frequencies of major clinical manifestations were: oral ulcers 99%, skin lesions 76%, genital ulcers 75%, ocular manifestations 59%, arthritis 59%, and positive pathergy test 52%. Clinical differences between German and Turkish patients were only found in the frequency of ocular lesions (48% vs. 66%, p = 0.025). Oral ulcers were with 72% the most common onset symptom of the disease followed by erythema nodosum (9%), uveitis (7%), arthritis (7%), genital ulcers (3%), superficial thrombophlebitis (2%) and papules/sterile pustules (2%). Uveitis and erythema nodosum as onset symptoms shortened the median interval to diagnosis to 1.5 and 15 months, respectively, while arthritis delayed diagnosis (43.5 months; p = 0.029). A severe course developed in 25% of the patients; irreversible retinal vasculitis to blindness in 15%, sterile meningoencephalitis in 8%, severe arthritis in 5%, hemoptysis in 2%, lethal outcome in 2% and bowel perforation in 1%. The relative risk of HLA-B5 positive German natives developing the disease. HLA-B5 was confirmed as a marker of severe prognosis. Cardiolipin autoantibodies were associated with cutaneous vasculitis and superficial thrombophlebitis was correlated with systemic vessel involvement.