High titer of serum antiphospholipid antibody levels in adult Henoch-Schnlein purpura and cutaneous leukocytoclastic angiitis.код для вставкиСкачать
Arthritis & Rheumatism (Arthritis Care & Research) Vol. 59, No. 4, April 15, 2008, pp 561–567 DOI 10.1002/art.23528 © 2008, American College of Rheumatology ORIGINAL ARTICLE High Titer of Serum Antiphospholipid Antibody Levels in Adult Henoch-Schönlein Purpura and Cutaneous Leukocytoclastic Angiitis TAMIHIRO KAWAKAMI,1 MASAHIDE YAMAZAKI,2 MASAKO MIZOGUCHI,1 AND YOSHINAO SOMA1 Objective. To investigate a possible role of antiphospholipid (aPL) antibodies in adult Henoch-Schönlein purpura (HSP) and cutaneous leukocytoclastic angiitis (CLA). Methods. We reviewed the records of 30 HSP and 8 CLA adults with an initial cutaneous manifestation of palpable purpura on their lower extremities between 2003 and 2007. Eight microscopic polyangiitis (MPA) patients and 30 healthy persons were recruited as controls. Serum anticardiolipin (aCL), anti–phosphatidylserine-prothrombin complex (antiPS/PT), and anti–␤2-glycoprotein I (anti-␤2GPI) antibody levels in HSP, CLA, MPA patients, and healthy controls were measured by enzyme-linked immunosorbent assay. Results. Twenty-two HSP patients (73%) were positive for serum IgA aCL antibodies. Nineteen (63%) had IgA anti-PS/PT antibodies and 4 (13%) had IgA anti-␤2GPI antibodies. IgA aCL and anti-PS/PT antibodies showed a signiﬁcant correlation (P ⴝ 0.007). Twenty (67%) HSP patients had IgM anti-PS/PT antibodies and 6 (20%) had IgG anti-PS/PT antibodies. Six (75%) CLA patients had IgM anti-PS/PT antibodies and 2 (25%) had IgG anti-PS/PT antibodies. In contrast, aPL antibodies were not found in any MPA patients or normal controls. Serum IgA aCL antibody levels in HSP patients showed a signiﬁcant correlation with serum IgA and C-reactive protein (CRP) levels (P ⴝ 0.030 and 0.039, respectively). A positive correlation between CRP and serum IgA anti-PS/PT antibody levels was observed in HSP patients (P ⴝ 0.023). Serum IgA aCL antibody levels were also signiﬁcantly associated with proteinuria according to urinalysis (P ⴝ 0.024). Conclusion. Serum levels of IgA aCL and anti-PS/PT antibodies were elevated in adult HSP, suggesting that serum IgA antibodies may play some role in adult HSP. IgA aCL and/or anti-PS/PT antibodies could serve as markers for adult HSP and should be monitored as an indicator of adult HSP activity. Small-vessel vasculitis could be dependently associated with the presence of IgM anti-PS/PT antibodies. These ﬁndings suggest that aPL antibodies are closely related to the pathogenic factors that trigger the development of vasculitis. INTRODUCTION Henoch-Schönlein purpura (HSP) is characterized by palpable nonthrombocytopenic purpura over the lower extremities, arthritis, abdominal pain with or without gastrointestinal hemorrhage, and, less commonly, glomerulo- Supported by grants from the Scientiﬁc Research Fund of the Ministry of Education, Science, Sports and Culture, Japan (Grant-in Aid for Scientiﬁc Research, 16591121 and 18591261). 1 Tamihiro Kawakami, MD, PhD, Masako Mizoguchi, MD, PhD, Yoshinao Soma, MD, PhD: St. Marianna University School of Medicine, Kawasaki, Japan; 2Masahide Yamazaki, MD, PhD: Kanazawa University Graduate School of Medical Science, Kanazawa, Japan. Address correspondence to Tamihiro Kawakami, MD, PhD, Department of Dermatology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Kanagawa 216-8511, Japan. E-mail: firstname.lastname@example.org. Submitted for publication June 26, 2007; accepted in revised form September 26, 2007. nephritis. Histologically, HSP reveals leukocytoclastic vasculitis, and has been well regarded as a speciﬁc clinicopathologic entity based on the vascular deposition of IgA-dominant immune complexes (ICs) (1,2). HSP in adulthood differs from the pediatric form of the disease. Adults have more pronounced skin lesions, and renal involvement is more frequent than in childhood (3,4). The pathogenesis of HSP remains poorly understood. The similarity of the histologic ﬁndings in HSP to those of Arthus reaction suggests an IgA IC–mediated disorder (5). Arthus reaction results from the deposition of ICs in the small blood vessels of the skin, glomeruli, and gastrointestinal tract and the subsequent activation of inﬂammatory responses to these complexes. This reaction has served as the basis for dissecting the cellular and molecular events that are triggered by IC deposition and serves as the basis for our understanding of the pathophysiology of ICmediated diseases. HSP has been associated with a history of preceding infection, particularly upper respiratory tract infection (URI). IgA is the principal antibody in the respi561 562 ratory system for defense against microbial agents. These ﬁndings raise the possibility of infection as a direct cause or a potential trigger of HSP. It has been postulated that various antigenic stimuli cause an elevation of circulating IgA and that complement activation leads to vasculitis. However, no deﬁnitive pathogen has been isolated from the majority of patients with HSP. We have previously shown high serum levels of IgA anticardiolipin (aCL) in adult HSP, suggesting that serum IgA aCL antibodies may play some role in the pathogenesis (6). Antiphospholipid (aPL) antibodies are a heterogeneous group of immunoglobulins that bind to several anionic phospholipids including cardiolipin and phosphatidylserine (7,8). Most aPL antibodies require a serum cofactor, ␤2-glycoprotein I (␤2GPI), for optimal binding (9 –12). It has been shown that many aPL antibodies may react to a neoepitope formed on the ␤2GPI molecule by the interaction between the phospholipid and ␤2GPI (13,14). Detection of aPL cofactor antibodies, in addition to the classic aCL antibodies, seems to be of considerable clinical importance. Prothrombin is another possible antigenic target of antiphospholipid syndrome (15). Atsumi et al (16) and Amengual et al (17) suggested that anti–phosphatidylserine-prothrombin complex (anti-PS/PT) antibodies alone, rather than antiprothrombin antibodies, are associated with symptoms of antiphospholipid syndrome. Small-vessel vasculitides are a group of inﬂammatory diseases that affect the arterioles, venules, and capillaries. These vasculitides can be divided into pauci-immune vasculitides associated with antineutrophil cytoplasmic antibodies (ANCAs) and immune deposit-associated vasculitides. The ANCA-associated vasculitides include microscopic polyangiitis (MPA), and HSP represents immune deposit-associated small-vessel vasculitides. The Chapel Hill Consensus Conference (CHCC) on the Nomenclature of Systemic Vasculitis deﬁned the term cutaneous leukocytoclastic angiitis (CLA) as isolated cutaneous leukocytoclastic angiitis without systemic vasculitis or glomerulonephritis (2). Thus, for the diagnosis of CLA, systemic involvement must be excluded (18). The diagnosis is one of exclusion because evidence of systemic vasculitic disease apart from arthralgias must be absent (19). In the present study, we diagnosed patients who did not have systemic vasculitis for at least 2 years during followup of CLA. To investigate the aPL antibodies of patients with HSP, CLA, and MPA, we examined the prevalence of aCL antibodies, anti-PS/PT antibodies, and anti-␤2GPI antibodies in 30 patients with HSP, 8 patients with CLA, and 8 patients with MPA. Furthermore, we investigated whether these antibodies are closely correlated with clinical or serologic features, which could indicate that IgA aCL and IgA anti-PS/PT antibodies could play a signiﬁcant role in the pathogenesis of HSP. PATIENTS AND METHODS Clinical investigation and tissue samples. Thirty Japanese patients with HSP (15 men, 15 women, mean ⫾ SD Kawakami et al age 56.4 ⫾ 20.1 years), 8 with CLA (6 men, 2 women, mean ⫾ SD age 56.6 ⫾ 19.1 years), and 8 with MPA (4 men, 4 women, mean ⫾ SD age 62.9 ⫾ 17.3 years) seen at the Department of Dermatology, St. Marianna University School of Medicine between 2003 and 2007 were examined. Patients presented with typical characteristics of nonthrombocytopenic symmetric palpable purpura over the lower extremities, and other conditions such as connective tissue diseases and infections had been excluded. Skin biopsy samples were obtained from patients during an active phase of their disease. Two skin biopsy samples from each of the 30 HSP and 8 CLA patients were taken for routine and direct immunoﬂuorescence (DIF) staining according to standard procedures. All biopsy samples were taken from the lower extremities. The tissue section was incubated with commercially prepared ﬂuoresceinated antisera speciﬁc to human IgG, IgM, IgA, or C3. Each of the skin biopsy samples showed ﬁbrinoid necrosis, an admixture of neutrophils and lymphocytes in and around the blood vessels, intravascular ﬁbrin thrombi, and nuclear dust characteristics of leukocytoclastic vasculitis in the upper and middle dermis. Based on DIF of the skin biopsy samples, vascular deposits of IgA in the dermis led to the diagnosis of HSP. The following selection criteria for HSP were used in the study: the presence of a leukocytoclastic vasculitis and vascular IgA and the absence of thrombocytopenia or known hematologic or connective tissue disorders. CLA is an isolated vasculitis limited to skin, and systemic involvement must be excluded. Apart from arthralgia, no systemic manifestations were observed after a minimum followup of 2 years. Eight MPA patients were diagnosed according to the CHCC deﬁnition (2), Sørensen et al criteria (20), and Japanese criteria (21). None of the patients had been given corticosteroids, immunosuppressants, or vasodilators at the time of serum sampling. Furthermore, no patient demonstrated any evidence of coexisting malignancy, other autoimmune diseases, or viral hepatitis, nor were any of the patients positive for mixed cryoglobulinemia. Thirty healthy persons with comparable sex and age distributions were recruited as normal controls. The following tests were negative or within the normal range in the HSP and CLA patients: antinuclear antibodies, ANCAs, and virus serology including hepatitis A, B, and C. Serologic studies. The ﬁrst immunologic assessments were performed on the serum collected at the same time as the skin biopsy samples. IgG, IgM, and IgA isotypes of anti-PS/PT antibodies and IgG, IgM, and IgA aCL antibodies were measured with a speciﬁc enzyme-linked immunosorbent assay (ELISA; Medical & Biological Laboratories, Nagoya, Japan) according to the manufacturer’s protocol. Brieﬂy, the serum samples were diluted 1:101, added to 96-well plates coated with PS/PT or aCL, and incubated for 1 hour at 20°C. Polyclonal gout anti-human IgG, IgM, and IgA antibodies labeled with horseradish peroxidase were used as conjugate solutions to recognize the 3 isotypes of PS/PT or aCL antibodies. Color was developed with 3,3⬘,5,5⬘-tetramethylbenzidine and H2O2 and the plates were read at 450 nm. IgA anti-␤2GPI anti- aPL Antibodies in HSP and Cutaneous Leukocytoclastic Angiitis 563 Table 1. Clinical, serologic, and DIF features in 30 patients with Henoch-Schönlein purpura* Patient no. Age Sex IgA aCL (APL) IgA PS/PT (units/ml) IgA ␤2GPI (units/ml) IgM PS/PT (units/ml) IgG PS/PT (units/ml) CRP (mg/dl) IgA (mg/dl) DIF with IgA 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 75 44 65 79 62 72 81 79 68 72 19 57 41 69 61 64 38 34 32 28 44 58 50 39 81 24 80 22 72 82 M F M F M M F M M M F F M F M M F M F M M F F F M F M F F F 18 11 21 16 11 16 24 11 24 – 11 11 – 11 18 12 11 12 13 13 13 11 15 – 13 – – – – – 18 14 42 14 13 – – 14 110 18 11 – 17 24 10 96 12 14 – 16 13 – 12 – 32 – – – – – – – 11 – – – – 18 – – – – – – 60 – – – – – – – – 18 – – – – – – 10 29 23 26 – 23 – 10 – 10 23 11 – – – 15 24 – 20 28 – 16 – 16 10 12 11 17 10 – 45 – – – – 29 – – 28 – – – – – 25 120 20 – – – – – – – – – – – – – 4.0 3.0 2.9 2.1 4.68 1.85 2.0 7.4 2.1 1.27 3.0 3.8 0.7 25.99 16.9 8.4 3.14 1.6 3.3 6.2 2.14 2.0 3.0 3.6 4.9 1.35 2.0 1.0 0.9 0.33 559 474 805 591 532 427 758 575 855 520 241 424 351 429 961 337 708 260 177 181 204 550 525 643 675 227 474 503 295 329 IgG, IgM, C3 C3 – IgM C3 IgM, C3 IgM, C3 – – C3 IgM, C3 C3 IgM, C3 C3 C3 IgM, C3 IgM, C3 IgM, C3 IgM, C3 C3 IgM, C3 C3 C3 IgM, C3 IgM, C3 – C3 C3 C3 IgM, C3 * DIF ⫽ direct immunoﬂuorescence; aCL ⫽ anticardiolipin antibodies; APL ⫽ IgA phospholipid units; PS/PT ⫽ phosphatidylserine-prothrombin complex; ␤2GPI ⫽ ␤2-glycoprotein I; CRP ⫽ C-reactive protein. bodies were measured with a speciﬁc ELISA (Bio-Rad Laboratories, Hercules, CA) according to the manufacturer’s protocol. IgG and IgM anti-␤2GPI antibodies were determined according to the standardized anti-␤2GPI antibody ELISA (Diagnostica Stago, Asnieres, France). The cutoff points were established by the mean ⫹5 SD of 50 controls. The following cutoff values were used: 12 units/ ml, 10 units/ml, and 10 units/ml for IgG, IgM, and IgA anti-PS/PT antibodies, respectively; 10 IgG phospholipid units, 10 IgM phospholipid units, and 10 IgA phospholipid units (APL units) for IgG, IgM, and IgA aCL antibodies, respectively; and 10 units/ml, 10 units/ml, and 10 units/ml for IgG, IgM, and IgA anti-␤2GPI antibodies, respectively. When ANCA was detected, speciﬁcity was characterized by ELISA for reactivity with myeloperoxidase or proteinase 3, using the technique recommended by the European ANCA Assay Standardization Group (22). All serum samples were stored at ⫺70°C prior to assay. Serum IgA and C-reactive protein (CRP) levels were assayed with laser nephelometry (Nihon Kohden, Tokyo, Japan). Statistical analysis. Kolmogorov-Smirnov test with Lilliefors signiﬁcance level was used to evaluate age, serum aPL antibodies, serum CRP level, and serum IgA. Statisti- cal analyses were performed using the Mann-Whitney U test for comparisons of serum aPL antibody levels. The Mann-Whitney U test was also used to compare blood parameter levels between positive and negative clinical symptoms (proteinuria, arthralgia, abdominal pain, and URI); the level of signiﬁcance was set at P ⬍ 0.05 in all cases. The correlation between serum IgA or CRP level and variation of the blood parameters was assessed by Spearman’s rank correlation test. All data are expressed as the mean ⫾ SD. The experimental protocol was approved by St. Marianna University, and informed consent was obtained from all patients (No. 1117). RESULTS IgA aCL antibodies, IgA anti-PS/PT antibodies, and/or IgA anti-␤2GPI antibodies were present in 25 (83%) of the 30 HSP patients; IgA aCL antibodies alone were present in 5 patients, IgA anti-PS/PT antibodies alone were present in 2 patients, and a combination of both types of antibodies was present in 17 patients (Table 1). IgA aCL antibodies were found in 22 (73%) of the 30 HSP patients, IgA antiPS/PT antibodies were found in 19 (63%), and IgA anti- 564 Kawakami et al Table 2. Clinical, serologic, and DIF features in 8 patients with cutaneous leukocytoclastic angiitis Patient no. Age Sex IgA aCL (APL) IgA PS/PT (units/ml) IgA ␤2GPI (units/ml) IgM PS/PT (units/ml) IgG PS/PT (units/ml) CRP (mg/dl) IgA (mg/dl) DIF 1 2 3 4 5 6 7 8 32 77 55 52 77 40 80 40 M M F M M F M M – – – – – – – – – – – – – – – – – – – – – – – – 16 18 13 – 21 10 – 16 – – – – 14 – – 12 0.16 3.2 0.6 3.0 1.1 0.08 0.3 3.1 239 392 121 364 253 187 221 350 IgM C3 C3 – IgG – – C3 * See Table 1 for deﬁnitions. ␤2GPI antibodies were found in 4 (13%). Of the 4 HSP patients with IgA anti-␤2GPI antibodies, 3 were found to be positive for IgA aCL antibodies and IgA anti-PS/PT antibodies. IgA aCL antibodies, IgA anti-PS/PT antibodies, and IgA anti-␤2GPI antibodies were not found in the serum of the CLA patients (Table 2), the MPA patients, or the healthy controls. Twenty (67%) of the HSP patients had positive titers for IgM anti-PS/PT antibodies and 6 (20%) had positive titers for IgG anti-PS/PT antibodies. By contrast, 6 (75%) of the 8 CLA patients were positive for IgM anti-PS/PT antibodies and 2 (25%) were positive for IgG anti-PS/PT antibodies. Serum IgA aCL levels were significantly elevated in all HSP patients (mean ⫾ SD 12.1 ⫾ 5.3 APL) in comparison with those of the CLA patients (mean ⫾ SD 4.8 ⫾ 2.4 APL) (Figure 1A). Serum IgA antiPS/PT levels were also signiﬁcantly higher among the HSP patients (mean ⫾ SD 18.5 ⫾ 24.6 units/ml) than the CLA patients (4.4 ⫾ 2.2 units/ml) (Figure 1B). The titers for IgM anti-PS/PT antibodies were similar between the HSP patients (mean ⫾ SD 13.1 ⫾ 8.1 units/ml) and CLA patients (13.6 ⫾ 5.0 units/ml), whereas these values were signiﬁcantly higher than those of the MPA patients and normal controls (Figure 1C). Levels of IgA anti-␤2GPI antibodies (mean ⫾ SD 6.6 ⫾ 10.9 units/ml versus 3.8 ⫾ 2.1 units/ml) and IgG anti-PS/PT antibodies (mean ⫾ SD 12.8 ⫾ 22.7 units/ml versus 5.5 ⫾ 4.7 units/ml) were not signiﬁcantly different between HSP patients and CLA patients. Laboratory investigations in the HSP patients revealed elevated serum IgA (mean ⫾ SD 486.3 ⫾ 206.7 mg/dl), as well as elevated CRP levels (mean ⫾ SD 4.2 ⫾ 5.2 mg/dl). We found a signiﬁcant correlation between serum IgA aCL antibodies and IgA anti-PS/PT antibodies in our HSP patients (rs ⫽ 0.50, P ⫽ 0.007) (Figure 2). There was a signiﬁcant positive correlation between serum IgA aCL antibodies and IgA levels (rs ⫽ 0.40, P ⫽ 0.030) (Table 3). A similar correlation was also seen between IgA aCL antibodies and CRP levels (rs ⫽ 0.38, P ⫽ 0.039). In addition, there was a positive correlation between serum IgA anti-PS/PT antibodies and CRP level (rs ⫽ 0.42, P ⫽ 0.023). The IgA anti-␤2GPI titer was significantly correlated with serum IgA and CRP level (rs ⫽ 0.52, P ⫽ 0.005 and rs ⫽ 0.44, P ⫽ 0.020, respectively). IgG anti-PS/PT antibodies were positively correlated with serum IgA (rs ⫽ 0.46, P ⫽ 0.014). Proteinuria according to urinalysis was noted in 24 (80%) of the 30 HSP patients. Serum IgA aCL antibody; IgG, IgM, and IgA anti-PS/PT antibody; and IgA anti-␤2GPI antibody concentrations in relation to the presence or absence of proteinuria in the HSP patients are listed in Table 4. Serum IgA aCL antibody levels differed signiﬁcantly between the proteinuriapositive and proteinuria-negative HSP patients (P ⫽ 0.024). A similar trend was seen with respect to IgG antiPS/PT antibodies (P ⫽ 0.045). Serum IgA aCL antibody, IgA anti-PS/PT antibody, and IgA anti-␤2GPI antibody levels did not differ signiﬁcantly between the HSP patients who were positive or negative for arthralgia, abdominal pain, and URI. There was no signiﬁcant correlation between IgM anti-PS/PT antibody in our CLA patients and arthralgia and URI. HSP is deﬁned as deposition of IgA into the dermal vessels as measured by DIF. In addition, DIF revealed C3 within the affected vessels in 25 (83%) of 30 HSP patients, IgM in 14 (47%), and IgG in 2 (6.7%). Patients 1 and 16 of the HSP patients with IgG deposits showed high serum levels of IgG anti-PS/PT antibody. We found no association between IgA alone (with or without C3) and IgG and/or IgM in the DIF testing. In the CLA biopsy samples, we found C3 deposits in 3 (38%) of the 8 patients, IgM in 1 (13%), and/or IgG in 1 (13%). DISCUSSION Twenty-two (73%) of our 30 Japanese adult HSP patients were positive for serum levels of IgA aCL antibodies. IgA aCL titers in the adult HSP patients were signiﬁcantly higher than those in the 8 CLA patients, 8 MPA patients, and 30 normal controls. In a previous study, 21 (81%) of 26 Chinese children with HSP had a higher prevalence of IgA aCL than healthy and juvenile rheumatoid arthritis control patients (23). In the present study, there was a signiﬁcantly greater presence of IgA anti-PS/PT antibodies in the HSP patients compared with the CLA patients, MPA patients, and normal controls. In addition, IgA aCL antibodies and IgA anti-PS/PT antibodies were signiﬁcantly correlated. We also found that there was a signiﬁcant positive correlation between serum IgA aCL antibodies and serum IgA level. IgA abnormalities suggest an immunologic basis for the pathogenetic mechanisms underlying HSP (23,24). Elevated serum IgA aCL antibody and/or IgA anti-PS/PT antibody levels may imply involvement of im- aPL Antibodies in HSP and Cutaneous Leukocytoclastic Angiitis 565 Figure 1. A, IgA anticardiolipin antibodies (aCL; antiphospholipid units), B, IgA anti–phosphatidylserine-prothrombin complex (anti-PS/PT; units/ml) antibody levels expressed as relative optical density, and C, IgM anti-PS/PT antibody levels (units/ml) were measured by ELISA in serum samples from normal controls and patients with Henoch-Schönlein purpura (HSP), cutaneous leukocytoclastic angiitis (CLA), and microscopic polyangiitis (MPA). The detection limit was 5 units/ml and the cutoff value was 10 units/ml. Horizontal lines indicate the mean value in each group. 566 Kawakami et al Table 4. Serum antiphospholipid antibody (aPL) concentrations associated with proteinuria in 30 patients with Henoch-Schönlein purpura* Serum aPL antibodies IgA aCL antibodies, APL† IgA anti-PS/PT antibodies, units/ml IgA anti-␤2GPI antibodies, units/ml IgM anti-PS/PT antibodies, units/ml IgG anti-PS/PT antibodies, units/ml‡ Figure 2. Positive correlation between serum IgA anti–phosphatidylserine-prothrombin complex (anti-PS/PT) antibody and IgA anticardiolipin (aCL) antibody levels in patients with HenochSchönlein purpura. Serum IgA anti-PS/PT antibody levels are shown on the ordinate, and serum IgA aCL antibody levels are shown on the abscissa (rs ⫽ 0.50, P ⫽ 0.007). munologic elements in the pathogenesis of HSP. Furthermore, we found a signiﬁcant correlation between serum IgA aCL antibodies, IgA anti-PS/PT antibodies, and CRP level in the 30 HSP patients. CRP is an inﬂammatory marker and an elevated CRP titer likely contributes to the aggressive clinical condition. Based on these ﬁndings, serum IgA aCL antibody and/or IgA anti-PS/PT antibody levels could serve as a marker for adult HSP and therefore should be monitored to appropriately gauge disease activity in adult HSP. Of the 30 HSP patients, 24 (80%) were positive for proteinuria according to urinalysis. Patients who subsequently developed proteinuria showed signiﬁcantly higher IgA aCL antibody levels than those without proteinuria. These ﬁndings suggest that monitoring serum IgA aCL antibody levels might be useful to predict renal involvement. We found IgM anti-PS/PT antibodies in 20 (67%) of the 30 HSP patients, but this ﬁnding was not correlated with IgA anti-PS/PT antibodies and/or IgA aCL antibodies. IgM anti-PS/PT antibodies were detected in 6 (75%) of our 8 CLA patients, but neither IgA anti-PS/PT antibodies nor IgA aCL antibodies were found in these patients. Smallvessel vasculitis (leukocytoclastic vasculitis), HSP, and CLA share a common pathologic background that may be related to the increased IgM anti-PS/PT antibody produc- Presence (n ⴝ 24) Absence (n ⴝ 6) 12.99 ⫾ 5.27 20.58 ⫾ 26.93 8.67 ⫾ 3.92 10.12 ⫾ 6.82 7.38 ⫾ 12.07 3.75 ⫾ 1.83 12.88 ⫾ 8.14 14.00 ⫾ 8.51 14.71 ⫾ 25.03 5.33 ⫾ 3.61 * Values are the mean ⫾ SD. See Table 1 for deﬁnitions. † P ⫽ 0.024. ‡ P ⫽ 0.045. tion in HSP and CLA. Phosphatidylserine is a regular constituent of the inner leaﬂet of the cell membrane, which is only exposed on the outside of the cell membrane during apoptosis or by damaged endothelial cells (25). Some studies have demonstrated that prothrombin binds speciﬁcally to the surface of apoptotic cells (26,27). We believe that prothrombin binds to apoptotic endothelial cells and combines phosphatidylserine in the dermis. The complexes may cause IgM anti-PS/PT antibody production in small-vessel vasculitis, which would probably be locally produced. In conclusion, we found high titers of serum IgA aCL antibodies and/or IgA anti-PS/PT antibodies in adult HSP patients, and there was a signiﬁcant association between these 2 markers. The 2 IgA antibodies were also positively correlated with CRP level. These IgA antibodies in HSP patients may reﬂect disease activity and play some pathogenic role. In contrast, serum IgM anti-PS/PT antibody levels were elevated in HSP and CLA patients, regardless of IgA aPL antibody levels. We speculate that IgM antiPS/PT antibodies could be implicated in disease susceptibility for leukocytoclastic vasculitis. These ﬁndings further suggest that aPL antibodies are closely related to the pathogenic factors that trigger the development of vasculitis. Further studies are required to conﬁrm the pathogenesis of HSP and CLA. Table 3. Correlation between antiphospholipid antibodies and serum IgA, CRP* Serum IgA rs P CRP rs P IgA aCL antibody IgA anti-PS/PT antibody IgA anti-␤2GPI antibody IgM anti-PS/PT antibody IgG anti-PS/PT antibody 0.40 0.030 0.30 0.105 0.52 0.005 ⫺0.09 0.64 0.46 0.014 0.38 0.039 0.42 0.023 0.44 0.020 0.09 0.62 * See Table 1 for deﬁnitions. 0.30 0.11 aPL Antibodies in HSP and Cutaneous Leukocytoclastic Angiitis AUTHOR CONTRIBUTIONS Dr. Kawakami had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study design. Kawakami. Acquisition of data. Kawakami, Yamazaki. Analysis and interpretation of data. Kawakami, Yamazaki. Manuscript preparation. Kawakami, Mizoguchi, Soma. Statistical analysis. Kawakami. REFERENCES 1. Knight JF. The rheumatic poison: a survey of some published investigations of the immunopathogenesis of HenochSchönlein purpura. Pediatr Nephrol 1990;4:533– 41. 2. Jennette JC, Falk RJ, Andrassy K, Bacon PA, Churg J, Gross WL, et al. Nomenclature of systemic vasculitides: proposal of an international consensus conference. Arthritis Rheum 1994; 37:187–92. 3. Nielsen HE. Epidemiology of Schönlein-Henoch purpura. Acta Paediatr Scand 1988;77:125–31. 4. Tancrede-Bohin E, Ochonisky S, Vignon-Pennamen MD, Flageul B, Morel P, Rybojad M. Schönlein-Henoch purpura in adult patients: predictive factors for IgA glomerulonephritis in a retrospective study of 57 cases. Arch Dermatol 1997;133: 438 – 42. 5. Lie JT. Nomenclature and classiﬁcation of vasculitis: plus ça change, plus c’est la même chose [editorial]. Arthritis Rheum 1994;37:181– 6. 6. Kawakami T, Watabe H, Mizoguchi M, Soma Y. Elevated serum IgA anticardiolipin antibody levels in adult HenochSchönlein purpura. Br J Dermatol 2006;155:983–7. 7. McNeil HP, Chesterman CN, Krilis SA. Immunology and clinical importance of antiphospholipid antibodies. Adv Immunol 1991;49:193–280. 8. Harris EN. Antiphospholipid antibodies. Br J Haematol 1990; 74:1–9. 9. McNeil HP, Simpson RJ, Chesterman CN, Krilis SA. Antiphospholipid antibodies are directed against a complex antigen that includes a lipid-binding inhibitor of coagulation: ␤2-glycoprotein I (apolipoprotein H). Proc Natl Acad Sci U S A 1990;87:4120 – 4. 10. Galli M, Comfurius P, Maassen C, Hemker HC, de Baets MH, van Breda-Vriesman PJ, et al. Anticardiolipin antibodies (ACA) directed not to cardiolipin but to a plasma protein cofactor. Lancet 1990;335:1544 –7. 11. Matsuura E, Igarashi Y, Fujimoto M, Ichikawa K, Koike T. Anticardiolipin cofactor(s) and differential diagnosis of autoimmune disease [letter]. Lancet 1990;336:177– 8. 12. Roubey RA. Immunology of the antiphospholipid antibody syndrome [review]. Arthritis Rheum 1996;39:1444 –54. 13. Wagenknecht DR, McIntyre JA. Changes in beta 2-glycoprotein I antigenicity induced by phospholipid binding. Thromb Haemost 1993;69:361–5. 567 14. Pengo V, Biasiolo A, Fior MG. Autoimmune antiphospholipid antibodies are directed against a cryptic epitope expressed when beta 2-glycoprotein I is bound to a suitable surface. Thromb Haemost 1995;73:29 –34. 15. Galli M, Luciani D, Bertolini G, Barbui T. Anti-beta 2-glycoprotein I, antiprothrombin antibodies, and the risk of thrombosis in the antiphospholipid syndrome. Blood 2003;102: 2717–23. 16. Atsumi T, Ieko M, Bertolaccini ML, Ichikawa K, Tsutsumi A, Matsuura E, et al. Association of autoantibodies against the phosphatidylserine-prothrombin complex with manifestations of the antiphospholipid syndrome and with the presence of lupus anticoagulant. Arthritis Rheum 2000;43:1982– 93. 17. Amengual O, Atsumi T, Koike T. Speciﬁcities, properties, and clinical signiﬁcance of antiprothrombin antibodies [review]. Arthritis Rheum 2003;48:886 –95. 18. Stone JH, Nousari HC. “Essential” cutaneous vasculitis: what every rheumatologist should know about vasculitis of the skin. Curr Opin Rheumatol 2001;13:23–34. 19. Carlson JA, Chen KR. Cutaneous vasculitis update: small vessel neutrophilic vasculitis syndromes. Am J Dermatopathol 2006;28:486 –506. 20. Sorensen SF, Slot O, Tvede N, Petersen J. A prospective study of vasculitis patients collected in a ﬁve-year period: evaluation of the Chapel Hill nomenclature. Ann Rheum Dis 2000; 59:478 – 82. 21. Tsuchiya N, Kobayashi S, Kawasaki A, Kyogoku C, Arimura Y, Yoshida M, et al. Genetic background of Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis: association of HLA-DRB1*0901 with microscopic polyangiitis. J Rheumatol 2003;30:1534 – 40. 22. Hagen EC, Daha MR, Hermans J, Andrassy K, Csernok E, Gaskin G, et al. Diagnostic value of standardized assays for anti-neutrophil cytoplasmic antibodies in idiopathic systemic vasculitis: EC/BCR Project for ANCA Assay Standardization. Kidney Int 1998;53:743–53. 23. Yang YH, Huang MT, Lin SC, Lin YT, Tsai MJ, Chiang BL. Increased transforming growth factor-␤ (TGF-␤)-secreting T cells and IgA anti-cardiolipin antibody levels during acute stage of childhood Henoch-Schönlein purpura. Clin Exp Immunol 2000;122:285–90. 24. Tizard EJ. Henoch-Schönlein purpura. Arch Dis Child 1999; 80:380 –3. 25. Austin A, Campbell E, Lane P, Elias E. Nodular regenerative hyperplasia of the liver and coeliac disease: potential role of IgA anticardiolipin antibody. Gut 2004;53:1032– 4. 26. D’Agnillo P, Levine JS, Subang R, Rauch J. Prothrombin binds to the surface of apoptotic, but not viable, cells and serves as a target of lupus anticoagulant autoantibodies. J Immunol 2003;170:3408 –22. 27. Price BE, Rauch J, Shia MA, Walsh MT, Lieberthal W, Gilligan HM, et al. Anti-phospholipid autoantibodies bind to apoptotic, but not viable, thymocytes in a ␤ 2-glycoprotein Idependent manner. J Immunol 1996;157:2201– 8.