Clinical practice guidelines of the Japan Research Committee of the Ministry of Health, Labour, and Welfare for Intractable Vasculitis for the management of microscopic polyangiitis and granulomatosis with polyangiitis: The 2023 update - secondary publication.

OBJECTIVE: To revise the 2017 clinical practice guidelines (CPG) for the management of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) to reflect advancements in the field. METHODS: Similar to the 2017 CPG, the Grading of Recommendations, Assessment, Development, and Evaluation system was adopted for this revision. The intended users of this CPG include patients diagnosed with MPA or GPA in Japan and their families and healthcare professionals, including specialists and non-specialists. Based on a scoping review, four clinical questions (CQs) of the 2017 guidelines were modified, and six new CQs were added. RESULTS: We suggest a combination of glucocorticoid and cyclophosphamide or rituximab for remission induction therapy. In cases where cyclophosphamide or rituximab is used, we suggest the use of avacopan over high-dose glucocorticoid. Furthermore, we suggest against the use of plasma exchange in addition to the standard treatment in severe cases of MPA/GPA. Finally, we suggest the use of glucocorticoid and rituximab over glucocorticoid and azathioprine for remission maintenance therapy. CONCLUSIONS: The recommendations have been updated based on patient preference, certainty of evidence, benefit and risk balance, and cost.

Expert perspectives on pathological findings in vasculitis.

Pathological findings are important in the diagnosis of vasculitis. However, due to the rarity of the disease, standard textbooks usually devote only a few pages to this topic, and this makes it difficult for clinicians not specializing in vasculitis to fully understand the pathological findings in vasculitis. To address the paucity of information, we present representative pathological findings in vasculitis classified in the 2012 Revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides (CHCC2012). The CHCC2012 classifies 26 vasculitides into seven categories: (1) large-vessel vasculitis, (2) medium-vessel vasculitis, (3) small-vessel vasculitis, including antineutrophil cytoplasmic antibody-associated vasculitis and immune complex small-vessel vasculitis, (4) variable-vessel vasculitis, (5) single-organ vasculitis, (6) vasculitis associated with systemic disease, and (7) vasculitis associated with probable aetiology. Moreover, representative pathological findings of vasculitis-related diseases and non-inflammatory vasculopathy not mentioned in the CHCC2012 are also presented. This will be useful for clinicians to refer to typical pathological findings of vasculitis in daily practice.

Elevated Myeloperoxidase-DNA Complex Levels in Sera of Patients with IgA Vasculitis.

INTRODUCTION: IgA vasculitis is a systemic disease that results from the entrapment of circulating IgA-containing immune complexes in small-vessel walls in the skin, kidneys, and gastrointestinal tract. An excessive formation of neutrophil extracellular traps (NETs) is involved in the pathogenesis of vasculitis, especially in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. This study aimed to clarify whether NETs are implicated in IgA vasculitis. METHODS: Twenty-two patients with IgA vasculitis and 4 healthy volunteers were enrolled in this study. Serum levels of myeloperoxidase (MPO)-DNA complex, a fragment derived from NETs, were determined by enzyme-linked immunosorbent assay (ELISA), and the association between MPO-DNA complex levels and clinical parameters was examined. The presence of the ANCA was also assessed by ELISA specific for MPO and proteinase 3 (PR3) and indirect immunofluorescence (IIF), followed by assessing the differences in clinical parameters with and without the ANCA. RESULTS: Serum MPO-DNA complex levels were significantly higher in patients with IgA vasculitis than those in healthy controls. A significant positive correlation between the serum MPO-DNA complex and IgA levels was noted. Interestingly, 63.6% of IgA vasculitis patients were ANCA-positive in IIF with an atypical pattern, whereas neither MPO-ANCA nor PR3-ANCA was detected by ELISA. These findings indicated that some IgA vasculitis patients possessed the so called minor ANCA. Serum IgA and MPO-DNA complex levels and the frequency of hematuria in the minor ANCA-positive group were significantly higher than in the minor ANCA-negative group. CONCLUSION: The collective findings suggested that NETs are certainly involved in the pathogenesis of IgA vasculitis.

Clinical characteristics and social productivity levels of patients with malignant rheumatoid arthritis based on a nationwide clinical database in Japan: annual survey from 2003 to 2013.

OBJECTIVES: Malignant rheumatoid arthritis (MRA) is defined as rheumatoid arthritis (RA) with systemic vasculitis or other severe extra-articular manifestations. Japan has a nationwide database for MRA. We analyzed the characteristics of Japanese patients with MRA based on data from the Ministry of Health, Labour and Welfare (MHLW). METHODS: We were permitted to use data on 43,108 patients who were registered in the MHLW database from 2003 to 2013. RESULTS: Median age was 65 (interquartile range, 57-72) years. Patients consisted of 71% females. Proportions of patients who had or had experienced interstitial pneumonia and pleuritis were increased, episcleritis was stable, and other MRA manifestations were decreased over time. The number of positive symptoms per patient also decreased over time. The median dose of glucocorticoid, percentage of patients undergoing surgery, and use of non-steroidal anti-inflammatory drugs and apheresis decreased year by year. Steinbrocker stage and class improved over time. Median C-reactive protein levels and erythrocyte sedimentation rate also decreased. Regarding social productivity levels of patients with MRA, the proportion of patients who were working or working from home increased and the proportion of patients recuperating or hospitalized decreased. CONCLUSION: In patients with MRA, disease activity decreased and social productivity improved from 2003 to 2013.

Formation and Disordered Degradation of Neutrophil Extracellular Traps in Necrotizing Lesions of Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is characterized by the production of ANCAs and systemic necrotizing vasculitis in small vessels. Disordered regulation of neutrophil extracellular traps (NETs) is critically involved in the pathogenesis of AAV. NETs are web-like DNA decorated with antimicrobial proteins; they are extruded from activated neutrophils. The principal degradation factor of NETs in vivo is DNase I; however, NETs resistant to DNase I can persist in tissues and can lead to the production of ANCAs. Deposition of NETs has been demonstrated in glomerular crescents and necrotizing vasculitis in AAV. Here, the amount of NETs in formalin-fixed, paraffin-embedded tissue sections was examined, and the results for AAV were compared with the results for diseases that should be distinguished from AAV. NETs were more abundant in necrotizing vasculitis of AAV than in non-ANCA-associated vasculitis, or in granulomatous angiitis. Pulmonary granulomas in AAV and non-ANCA-associated diseases were further studied. The amount of NETs was significantly greater in necrotizing granulomas of AAV than in granulomas of sarcoidosis without necrosis. Although NETs were formed in necrotizing granulomas of tuberculosis equivalently to those formed in AAV, they were more susceptible to degradation by DNase I than were NETs in AAV. The formation and disordered degradation of NETs in necrotizing lesions are characteristics of AAV and are possibly related to its pathogenesis.

Relationship between lysosomal-associated membrane protein-2 and anti-phosphatidylserine/prothrombin complex antibody in the pathogenesis of cutaneous vasculitis.

OBJECTIVES: We investigated the relationship between lysosomal-associated membrane protein-2 (LAMP-2) and anti-phosphatidylserine/prothrombin (PS/PT) antibody in the pathogenesis of cutaneous vasculitis. METHODS: Cell surface LAMP-2 expression of human neutrophils was measured using flow cytometry. Twenty inbred wild-type Wistar-King-Aptekman-Hokudai (WKAH) rats were divided into four groups: Group 1, rabbit IgG injection only as negative control (n=5); Group 2, both histone and rabbit IgG injection (n=5); Group 3, anti-LAMP-2 antibody injection only (n=5); and Group 4, both histone and anti-LAMP-2 antibody injection (n=5). Ten WKAH rats were divided into two groups: Group A, histone, anti-PS/PT antibody, and anti-LAMP-2 antibody injection (n=5), and Group B, histone, anti-PS/PT antibody, and rabbit IgG injection as control (n=5). RESULTS: LAMP-2 expression on human neutrophils was induced by cell-free histone exposure in a dose- and time-dependent manner. Histopathological examination revealed the recruitment of neutrophils in cutaneous small vessels in all Group 4 rats. These observations were not evident in systemic organs other than the skin. LAMP-2 expression on the surface of vascular endothelial cells was evident in Group 2, exclusively in the skin, but not in Group 1. Thrombi were detected in various organs in all Groups A and B rats. However, no apparent thrombi were observed in the skin. CONCLUSIONS: Anti-PS/PT and anti-LAMP-2 antibodies are responsible for independent effector mechanisms in the rats given intravenous injection of cell-free histones. We considered that undetermined factors other than cell-free histones could be required for the induction of cutaneous vasculitis by anti-PS/PT and anti-LAMP-2 antibodies.

2017 Clinical practice guidelines of the Japan Research Committee of the Ministry of Health, Labour, and Welfare for Intractable Vasculitis for the management of ANCA-associated vasculitis.

OBJECTIVE: The Japan Research Committee for Intractable Vasculitis has fully revised the clinical practice guidelines (CPG) for the management of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) to improve and standardize the medical treatment of the disease in Japan. METHODS: The previous CPG was published in a classical review style in Japanese in 2011 and 2014. We adopted the Grading of Recommendations Assessment, Development and Evaluation system for this revision, and various stakeholders, including patients, participated in it. The expected users of this CPG are AAV patients in Japan and their families and healthcare professionals, including both AAV specialists and non-specialists. We set clinical questions concerning the three important clinical topics of remission induction therapy, plasma exchange, remission maintenance therapy, and developed eight recommendation statements. RESULTS: For remission induction therapy for newly developed AAV, we weakly recommend glucocorticoid (GC) plus intravenous cyclophosphamide pulse (IVCY) or oral cyclophosphamide (POCY) rather than GC alone, and IVCY rather than POCY. We also weakly recommend CY rather than rituximab. In the case of AAV with severe renal impairment, we weakly recommend plasma exchange as a conjunction therapy. We weakly recommend azathioprine for remission maintenance therapy. CONCLUSION: The revised CPG has demonstrated evidence-based treatment recommendations for AAV.

Establishment of a rat model of thrombosis induced by intravenous injection of anti-phosphatidylserine-prothrombin complex antibody.

Objective: Recent studies have suggested that aPS-PT antibody is one of the most relevant autoantibodies to APS. This study aimed to demonstrate the pathogenicity of aPS-PT antibody in vivo . Methods: At first, cultured rat vascular endothelial cells (RECs) were exposed to calf thymus-derived histones. Two hours later, lactate dehydrogenase release from the RECs and expression of PS on the cell surface were assessed. Next, we administered an i.v. injection of calf thymus-derived histones into Wistar rats (12.5 µg/g weight of 8-week-old female rats), and 2 h later they were given an i.v. injection of aPS-PT mAb (1.25 mg/g weight, n = 6) or an equal dose of rat IgM as controls (n = 5). Three days later, histological examination was conducted. Results: Calf thymus-derived histones (>12.5 µg/ml) could injure RECs in vitro . Simultaneously, annexin V could bind to the RECs; thereby, this result indicated that cell-free histone exposure of vascular endothelial cells induced cell surface expression of PS, which is naturally present inside the plasma membrane. Thrombosis developed with higher frequency in the rats given an i.v. injection of aPS-PT mAb than in controls. Conclusion: We established a rat model of thrombosis induced by i.v. injection of aPS-PT mAb.

Lysosomal-associated membrane protein-2 plays an important role in the pathogenesis of primary cutaneous vasculitis.

OBJECTIVES: Recent research suggests that lysosomal-associated membrane protein-2 (LAMP-2) could be one of the target antigens in the pathogenesis of vasculitides. We established a transgenic rat model, env-pX rats, with various vasculitides including cutaneous vasculitis. Human primary cutaneous vasculitis includes cutaneous polyarteritis nodosa (CPN) and Henoch-Schönlein purpura (HSP). We measured serum anti-LAMP-2 antibody levels in morbid env-pX rats and injected anti-LAMP-2 antibody into premorbid env-pX rats. We further measured serum anti-LAMP-2 antibody levels in patients with CPN and HSP. METHODS: Cutaneous vasculitis was observed in ∼30% of 6-month-old morbid env-pX rats. In contrast, these findings were rare in premorbid env-pX rats under 3 months old. We also examined 85 patients with CPN and 36 adult patients with HSP. Serum anti-LAMP-2 antibody levels were determined using ELISA. Premorbid env-pX rats under 3 months old were given an i.v. injection of anti-LAMP-2 antibody at day 0 and day 7. At day 14, these rats underwent histopathological and direct immunofluorescence examination. Cell surface LAMP-2 expression of rat neutrophils was examined by flow cytometry. RESULTS: Serum anti-LAMP-2 antibody levels were significantly higher in morbid env-pX rats than in wild-type normal rats. In addition, the levels in the cutaneous vasculitis group of morbid env-pX rats were significantly higher than the no cutaneous vasculitis group. Intravenous anti-LAMP-2 antibody injection into premorbid env-pX rats under 3 months old induced infiltration of neutrophils into cutaneous small vessels. Anti-LAMP-2 antibody-binding neutrophils were detected there. LAMP-2 expression on the cell surface of neutrophils in premorbid env-pX rats under PMA stimulation was higher compared with controls. Serum anti-LAMP-2 antibody levels in CPN and HSP were significantly higher than those of healthy controls. CONCLUSION: These data support a positive relationship between anti-LAMP-2 antibody and cutaneous vasculitis.

Serum anti-lysosomal-associated membrane protein-2 antibody levels in cutaneous polyarteritis nodosa.

Lysosomal-associated membrane protein-2 (LAMP-2) is a target antigen for anti-neutrophil cytoplasmic antibodies (ANCAs), which are closely linked to a subset of primary systemic vasculitides. Cutaneous polyarteritis nodosa (CPN) is a necrotizing vasculitis of small to medium-sized arteries within the skin. We measured levels of serum anti-LAMP-2 antibody in 50 patients with CPN, 8 with microscopic polyangiitis (MPA), and 34 healthy persons. We also investigated the presence of ANCA in patients with CPN using indirect immunofluorescence (IIF), a direct ELISA and a capture ELISA specific for myeloperoxidase (MPO) and proteinase 3 (PR3). Serum anti-LAMP-2 antibody levels differed significantly between patients with CPN (0.263 U/ml) and those with MPA (0.180 U/ml) (p = 0.0102). Serum of all patients with CPN was negative for MPO-ANCA and PR3-ANCA by both direct ELISA and capture ELISA. In contrast, IIF assay revealed ANCA in 42 (84.0%) of the 50 CPN patients. Serum anti-LAMP-2 antibody levels in the perinuclear ANCA (P-ANCA) group were significantly elevated compared with the non-ANCA group (p = 0.0147). We suggest that anti-LAMP-2 antibody could play an important role in the pathogenesis of CPN in the presence of P-ANCA detected by IIF.

Presence of eosinophil extracellular trap cell death in the affected skin of eosinophilic granulomatosis with polyangiitis.

Eosinophil activation in tissue might be associated with disease severity. Eosinophil cytolysis, a process of active cell death, has been referred to as eosinophil extracellular trap cell death (EETosis). In the present study, the authors investigated EETosis in the affected skin of four patients with eosinophilic granulomatosis with polyangiitis (EGPA) using an immunofluorescence staining method. Immunofluorescence staining for myelin basic protein, galectin-10, and DNA revealed various degrees of EETosis and Charcot-Leyden crystals in skin tissue, suggesting the different degree of eosinophil activation status. The histopathological characteristic features may help physicians establish an earlier diagnosis of intractable eosinophilic-related disease including EGPA. Furthermore, ETotic eosinophil infiltration in perineurium of skin tissue might play a primary role in peripheral neuropathy of this disorder.

Clinical guidance of pyoderma gangrenosum 2022.

Pyoderma gangrenosum (PG) is a rare, neutrophilic skin disease. For the purpose of accurate diagnosis and proper treatment of PG, the Japanese clinical practice guidance for PG developed by the Japanese Dermatological Association was published in 2022. In this guidance, clinical aspects, pathogenesis, current therapies, and clinical questions on PG are described from the viewpoints of current knowledge and evidence-based medicine. Here, the English version of the Japanese clinical practice guidelines for PG is presented and is intended to be widely referred to in the clinical examination and treatment of PG.

Mizoribine treatment for antihistamine-resistant chronic autoimmune urticaria.

Chronic autoimmune urticaria is routinely diagnosed using an autologous serum skin test. Mizoribine is a newly developed immunosuppressive agent that has low toxicity. The pharmacological effects of mizoribine are similar to those of another purine biosynthesis inhibitor, mycophenolate mofetil. A 57-year-old woman presented with recurrent wheals and was insufficiently managed with administration of antihistamines, antileukotrienes, oral corticosteroids, and cyclosporine. She was positive in the autologous serum skin test. Oral mizoribine therapy was started as a combination therapy with prednisolone. The patient achieved a dramatic improvement in symptoms and complete resolution of the urticaria a few days after adding mizoribine to her treatment. The prednisolone was tapered after the start of mizoribine treatment. Her symptoms did not flare up, and no side effects were observed. In vitro basophil histamine release assays suggested that she might have anti-IgE autoantibody-type histamine release activity. We believe that mizoribine has a therapeutic role in some patients with chronic autoimmune urticaria and may be useful for treatment of cases not responsive to classical therapy. We suggest that mizoribine might help to reduce anti-IgE autoantibody acting on the surface of basophils in chronic autoimmune urticaria.

Therapeutic effect of mizoribine on pemphigus vulgaris and pemphigus foliaceus.

We evaluated the effectiveness of mizoribine, a newly developed immunosuppressive agent, as an adjuvant therapy in the treatment of both pemphigus vulgaris and pemphigus foliaceus. Eleven pemphigus patients (eight pemphigus vulgaris and three pemphigus foliaceus) received the combination therapy of prednisolone and mizoribine. Complete remission was observed in three of the eight patients with pemphigus vulgaris and in one of the three patients with pemphigus foliaceus. The four patients with complete remission had a rapid clinical response and achieved remission at a median of 11.8 months. Partial remission was achieved in two of the three patients with pemphigus foliaceus. The median time to achieve partial remission was 16.0 months. Six (55.6%) of the 11 patients with pemphigus had complete or partial remission and were able to taper their prednisolone. The cumulative probability of having a complete remission was 64.3% at 19 months of follow-up using Kaplan-Meier analysis. The effectiveness of the additional mizoribine therapy could be attributed to its corticosteroid-sparing properties as well as its immunosuppressive effects. The serum concentration titer of mizoribine was around 1.0 µg/mL 2 hours after administration. Patients who were not improved by the additional mizoribine might require a continuously higher dose of mizoribine to achieve effective therapy.

Low-dose cyclosporin improves the health-related quality of life in Japanese psoriasis patients dissatisfied with topical corticosteroid monotherapy.

Psoriasis greatly impacts the health-related quality of life of patients, including any dermatological conditions that are listed in the dermatology life quality index (DLQI). We investigated the relationships between DLQI and the degree of patient satisfaction using questionnaires among psoriasis patients treated only with topical corticosteroids. Patients who were dissatisfied with topical corticosteroids alone and agreed to receive cyclosporin were given low-dose oral cyclosporin. We assessed changes of the DLQI and the psoriasis area and severity index (PASI) scores in patients dissatisfied with treatment during the period of cyclosporin addition. Of 32 enrolled patients, 17 reported dissatisfaction with the current treatment of topical corticosteroids alone. There was a significantly positive correlation between the degree of patient satisfaction questionnaires and the DLQI of these 32 patients. Among the 17 dissatisfied patients, 12 patients agreed to receive additional cyclosporin therapy and five did not. The 12 patients who started on cyclosporin had a significantly lower PASI after 12 weeks than they did at baseline. The DLQI improved significantly after 12 weeks in the cyclosporin-treated patients. The 12 patients who agreed to receive cyclosporin showed a significantly lower DLQI at 12 weeks compared to the five patients who declined the addition of cyclosporin to their treatment. Assessing the degree of patient satisfaction with therapy using a questionnaire could be useful for improving clinical interventions in psoriasis patients. Low-dose oral cyclosporin could be effective in patients who are dissatisfied with topical corticosteroid treatment alone.

Surgical procedures and innovative approaches for vitiligo regenerative treatment and melanocytorrhagy.

Surgical treatments for vitiligo are a safe and effective treatment modality for select patients with vitiligo. Many techniques of vitiligo surgery exist, each with unique advantages and disadvantages. We reviewed the various surgical therapies and innovative approaches for vitiligo regenerative treatment reported in the literature. Surgical therapies can be subdivided into tissue grafting methods and cellular grafting methods. Tissue grafting methods mainly include mini punch grafts, suction blister roof grafts, and hair follicle grafts. Cellular grafting methods include cultured and non-cultured treatments. The efficacy needs to be improved largely due to the poor proliferation and quality of the autologous melanocytes. Rho-associated protein kinase inhibitor enhances primary melanocyte culture proliferation from vitiligo patients to prevent apoptosis. Innovative approaches using stem cell methods could prove invaluable in developing a novel cell therapy for patients suffering from vitiligo. We succeeded in inducing melanin pigmentation in mice skin in vivo using our human induced pluripotent stem cell-derived melanocytes. In addition, we reviewed melanocytorrhagy, detachment and transepidermal loss of melanocytes, and melanocyte-related adhesion molecules. These adhesion molecules include epithelial cadherin, discoidin domain receptor tyrosine kinase 1, glycoprotein non-metastatic melanoma protein B, macrophage migration inhibiting factor, 17ß-hydroxysteroid dehydrogenase 1, and E26 transformation-specific 1.

Heliotrope-like manifestation of adult-onset Still disease with macrophage activation syndrome: A case-based review.

Adult-onset Still disease (AOSD) has been typically associated with an evanescent skin rash that appears during febrile episodes. Subsequently, reports of a more persistent rash have appeared in the literature, referred to as the atypical rash of AOSD. The atypical nonevanescent rash can be usually divided into dermographism-like, lichenoid, and dermatomyositis-like lesions. Some authors have suggested that AOSD with the atypical rash could be severe, with a poor prognosis. We describe the case of a Japanese woman with AOSD characterized by persistent pruritic lesions resembling those observed in heliotrope manifestation of dermatomyositis. We conducted a literature review of clinical cases of AOSD on MEDLINE and the Web of Science. We identified nine cases of atypical rash of the eyelids, heliotrope-like manifestation of AOSD in addition to our case. All nine patients were female and they had a mean age of 39.3 ± 2.8 years. Four (44.4%) patients had macrophage activation syndrome (MAS) or disseminated intravascular coagulation (DIC) as complications and our case was the only one associated with both MAS and DIC. When a clinician encounters a female patient with heliotrope-like rash resembling those observed in dermatomyositis, the underrecognition of the skin manifestations may result in delayed diagnosis of AOSD. We believe that physicians should identify this type of cutaneous lesion to diagnose AOSD earlier and administer adequate treatment. Although the contribution of tocilizumab to the occurrence of MAS has not been determined, careful observation should be considered during tocilizumab therapy in patients with active AOSD.

Presence of neutrophil extracellular traps in superficial venous thrombosis of Behçet's disease.

Behçet's disease (BD) has a heterogeneous spectrum of disease manifestations featuring the involvement of different organs and can be characterized with different symptoms depending on the clinical department in charge. We retrospectively reviewed BD patients seen at our hospital and investigated the presence of neutrophils producing neutrophil extracellular traps (NET) in those patients. Immunolabeling of myeloperoxidase and histone citrullination proteins was performed on skin biopsies from three BD patients who had skin biopsy-proven superficial vein thrombophlebitis in their erythema nodosum-like lesions. We observed a higher proportion of female patients and a higher incidence of acne-like eruptions among BD patients seen at our dermatology department, while there was a higher incidence of ocular and gastrointestinal involvement among BD patients treated in other departments. We suggest that sex statistical trends could lead to the co-development of different manifestations and may help clinicians choose the best therapeutic approaches, tailoring them to the specific phenotype of the patient rather than one based on single disease manifestations. NET were found in neutrophils of panniculitis concurrent with superficial vein thrombophlebitis. We suggest that the pathogenesis of BD-related thrombosis could be associated with neutrophil activation and NET are released in the panniculitis of affected skin lesions, erythema nodosum-like lesions.

Typical cutaneous small-vessel vasculitis induced by combined injection of antiphosphatidylserine/prothrombin complex antibody and anti-LAMP-2 antibody in normal rats.

We previously reported that IgA vasculitis and cutaneous arteritis could be dependently associated with the presence of the antiphosphatidylserine/prothrombin complex (anti-PS/PT) antibody and lysosomal-associated membrane protein-2 (LAMP-2). The copy number of LAMP-2 mRNA in skin tissue samples from rats with cutaneous vasculitis induced by intravenous administration of anti-PS/PT antibody after subcutaneous histone injection was significantly higher than in those without cutaneous vasculitis. We found LAMP-2 protein overexpression in neutrophils and vascular endothelial cells of the affected blood vessels in rats with cutaneous vasculitis induced by intravenous administration of anti-PS/PT antibody after cutaneous priming by histones. We found typical cutaneous small-vessel vasculitis in the skin of rats given intravenous injection of both anti-PS/PT antibody and anti-LAMP-2 antibody after cutaneous priming by histones. We suggested that the introduction of skin local histones and anti-PS/PT antibody in serum could move LAMP-2 to the cell surface of neutrophils and vascular endothelial cells, and that anti-LAMP-2 antibody could bridge these cells through antigen-specific binding in typical cutaneous small-vessel vasculitis.