Outcomes and risk factors for failure after débridement, antibiotics, and implant retention for elbow periprosthetic joint infection.

BACKGROUND: Evidence for the management of periprosthetic joint infection (PJI) after total elbow arthroplasty is sparse, particularly in regard to débridement, antibiotics, and implant retention (DAIR). This study explored the outcomes of DAIR and analyzed risk factors for failure. METHODS: A retrospective cohort study of patients 18 years or older diagnosed with elbow PJI and managed with DAIR between January 1, 2003, and December 31, 2018, at a single institution was performed. Twenty-six elbows met the inclusion criteria during the study period. All DAIR procedures included in this study represented an attempt to manage an acute PJI with surgical irrigation and débridement without removal of the elbow arthroplasty components, followed by long-term systemic antimicrobial therapy. DAIR failure was defined as recurrence of PJI, unplanned re-operation for infection, or death secondary to infection. A Cox proportional hazards model was used to identify possible risk factors for failure. RESULTS: DAIR failed in 17 cases of elbow PJI with a failure rate of 65% at 2 years (95% confidence interval: 41.3%-79.6%). The median time to failure from DAIR was 43 days (interquartile range: 27-114). We found that DAIR failed in all cases with sinus tracts or negative cultures. The group with favorable outcomes had a shorter median duration of symptoms (5 vs. 18 days, P = .65) and a higher proportion of monomicrobial infections (58.8% vs. 88.9%, P = .19) compared to those with unfavorable outcomes. However, with the numbers available, none of the possible risk factors analyzed for association with failure reached statistical significance. CONCLUSION: DAIR for elbow PJI was associated with high rates of failure. Possible risk factors for failure may include the presence of sinus tract, longer duration of symptoms, and culture-negative infection. Although the relatively low morbidity of DAIR compared with total elbow arthroplasty implant resection for a one-stage or two-stage reimplantation is attractive, patients considered for DAIR must know that the chance of success is limited to approximately 35%.

A potentiometric and spectrofluorimetric approach to unravel inhibitory effects of semi- and thiosemicarbazones on mushroom tyrosinase activity.

The inhibitory effects on mushrooms tyrosinase activity of some semi- and thiosemicarbazones were investigated. While the semicarbazones are inactive, the thiosemicarbazones are, in general, more active than the reference (kojic acid, IC50 = 70 µM), with maximum activity obtained with benzaldehyde thiosemicarbazone (IC50 = 7 µM). These inhibitors probably act by coordination of the copper(II) metal ions in the active site of tyrosinase: effectively, potentiometric studies conducted in water solutions confirm that the most active thiosemicarbazone is a good ligand for copper(II) ions. The tyrosinase CD spectra do not show any significant difference by addition of an inhibitor or an inactive compound. On the contrary, interesting results were obtained by spectrofluorimetric titrations of mushrooms tyrosinase aqueous solutions with some of the investigated compounds, giving helpful information about possible mechanism of action. The thiosemicarbazones here reported are not cytotoxic on human fibroblasts and do not activate cells in a pro-inflammatory way.

Virtual surgical planning and mirrored, 3-dimensionally printed guides for corrective clavicle osteotomies in clavicle malunions and nonunions.

BACKGROUND: The objective of this study was to retrospectively review clinical and radiographic outcomes of patients who underwent corrective osteotomies for clavicle malunion and internal fixation for nonunion using a combination of virtual surgical planning, patient-specific 3-dimensional (3D)-printed clavicles, and 3D-printed cutting guides manufactured at the point of care. METHODS: Between 2015 and 2021, 18 patients underwent corrective osteotomy for a clavicle malunion (7 shoulders) or internal fixation for a clavicle nonunion (11 shoulders). There were 11 male and 7 female individuals with an average patient age of 43.9 (range 19-76) years. All patients underwent computed tomography evaluation of both clavicles. The DICOM files were manually segmented, virtual surgical planning was performed selectively using commercially available software, and a mirrored version of the normal clavicle was 3D printed along with a 3D-printed replica of the affected clavicle. Three-dimensionally printed mirrored clavicles were used in all cases to ensure adequate restoration of the shape and length of the clavicle and to precontour fixation plates. Virtual surgical planning and 3D-printed cutting guides for osteotomy were used in 4 of 18 (22%) patients. Either cancellous or structural intercalary bone grafting was used in 15 of 18 (83%) cases. Patients were contacted postoperatively to determine clinical outcome scores. Preoperative, early postoperative, and late postoperative radiographs were reviewed to assess for union and complications. The average follow-up time was 24.9 months. RESULTS: Radiographic evaluation at the most recent follow-up demonstrated adequate restoration of length and successful union for all shoulders. There were no complications or reoperations. Postoperative patient-reported outcomes could be obtained in 16 of 18 (88.9%) patients. At the most recent follow-up, the mean visual analog scale for pain was 2.38 points (range, 1-7), the mean shoulder American Shoulder and Elbow Surgeons score was 73.2 points (range, 25-100), and the mean Patient-Reported Outcome Measurement Information System Upper Extremity score was 26 points (range, 7-35). All (100%) the patients were satisfied with their outcome (9 very satisfied, 7 satisfied), and their mean subjective shoulder value was 73% (range, 10%-100%). However, 2 patients complained of hardware-related symptoms, and 1 patient had return of preoperative symptoms after an interim 2 years of pain relief. CONCLUSION: The use of mirrored 3D-printed clavicles combined with virtual surgical planning and patient-specific 3D guides provides a reliable technique for restoring native anatomy when performing corrective osteotomies for clavicle malunion or internal fixation for clavicle nonunion, with a high rate of satisfactory clinical and radiographic outcomes.

Arthroscopic release of the pectoralis minor tendon from the coracoid for pectoralis minor syndrome.

PURPOSE: The term "pectoralis minor syndrome" refers to this constellation of symptoms that can occur when the pectoralis minor (Pm) is shortened and contracted. Release of the tendon of the Pm from the coracoid has been reported to provide substantial clinical improvement to patients presenting with pectoralis minor syndrome. The purpose of this study was (1) to describe the technique for endoscopic release of pectoralis minor tendon at the subdeltoid space, (2) to classify the pectoralis minor syndrome according to its severity and (3) and to report the short-term outcomes of this procedure in a consecutive series of patients diagnosed with pectoralis minor syndrome. METHODS: Endoscopic release of the pectoralis minor tendon was performed in a series of 10 patients presenting with pectoralis minor syndrome. There were six females and four males with a median age at the time of surgery of 42 (range from 20 to 58) years. Four shoulders were categorized as grade I (scapular dyskinesis), and six as grade II (intermittent brachial plexopathy). Shoulders were evaluated for pain, motion, satisfaction, subjective shoulder value (SSV), quick-DASH, ASES score, and complications. The mean follow-up time was 19 (range, 6 to 49) months. RESULTS: Arthroscopic release of the tendon of the Pm led to substantial resolution of pectoralis minor syndrome symptoms in all but one shoulder, which was considered a failure. Preoperatively, the median VAS for pain was 8.5 (range, 7-10) and the mean SSV was 20% (range, 10% - 50%). At most recent follow-up the mean VAS for pain was 1 (range, 0-6) and the mean SSV 80% (range, 50% - 90%). Before surgery, mean ASES and quick-DASH scores were 19.1 (range, 10-41.6) and 83.1 (range, 71 and 95.5) points respectively. At most recent follow-up, mean ASES and quick-DASH scores were 80.1 (range, 40-100) and 19.3 (range, 2.3-68) points respectively. No surgical complications occurred in any of the shoulder included in this study. CONCLUSIONS: Endoscopic release of the tendon of the pectoralis minor from the coracoid improves pain, function and patient reported outcomes in the majority of patients presenting with the diagnosis of isolated pectoralis minor syndrome.

Sonication improves microbiologic diagnosis of periprosthetic elbow infection.

BACKGROUND: Periprosthetic joint infection (PJI) is a relatively frequent and oftentimes devastating complication after total elbow arthroplasty (TEA). Its microbiologic diagnosis is usually based on periprosthetic tissue culture (hereafter referred to as tissue culture), but the sensitivity of tissue culture is variable. Although implant sonication culture has been shown to be superior to tissue culture for the diagnosis of hip and knee PJI, only a single small study (of fewer than 10 infected implants) has assessed sonication for PJI diagnosis after elbow arthroplasty. METHODS: We retrospectively analyzed 112 sonicate fluid cultures from patients who underwent revision of a TEA at a single institution between 2007 and 2019, comparing results to those of tissue cultures. We excluded patients who had fewer than 2 tissues submitted for culture. Using the Infectious Diseases Society of America guidelines to define PJI, there were 49 infected and 63 non-infected cases. Median ages in the PJI and non-infected groups were 66 and 61 years, respectively. In the non-infected group, 65% were female vs. 63% in the PJI group. We reviewed clinical characteristics and calculated the sensitivity and specificity of tissue compared with sonicate fluid culture. In addition, we compared the sensitivity of tissue culture to the combination of tissue and sonicate fluid culture. RESULTS: The most common pathogens were coagulase-negative Staphylococcus sp (49%), followed by Staphylococcus aureus (12%). Sensitivity of tissue culture was 63%, and sensitivity of sonicate fluid culture was 76% (P = .109). Specificity of tissue culture was 94% and specificity of sonicate fluid culture was 100%. Sensitivity of sonicate fluid culture in combination with tissue culture was 84% (P = .002 compared to tissue culture alone). CONCLUSION: In this study, we found that the combination of sonicate fluid and tissue culture had a greater sensitivity than tissue culture alone for microbiologic diagnosis of PJI after TEA.

Hydroxyphenyl thiosemicarbazones as inhibitors of mushroom tyrosinase and antibrowning agents.

Tyrosinase is a metalloenzyme involved in o-hydroxylation of monophenols and oxidation of o-diphenols to o-quinones, with formation of brown or black pigments (melanines). Tyrosinase inhibitors are of great interest in medicine and cosmetics (skin whitening compounds), but also in food and beverage industry (antibrowning agents). Here we report on the activity as mushroom tyrosinase inhibitors of a series of hydroxyphenyl thiosemicarbazones (1-5): one of them revealed an inhibitory activity stronger than kojic acid, used as reference. Enzymatic inhibition activity was confirmed by colorimetric measurements on small wheels of Fuji apples treated with the hydroxyphenyl thiosemicarbazones. The mechanism of action of compounds 1-5 was investigated by molecular modelling and by studying in solution their speciation with Cu(II) ions, the ions in the active site of the enzyme. Finally, compounds 1-5 were tested on human fibroblasts: they are not cytotoxic and they do not activate cells in a pro-inflammatory way.

Vitamin D replacement ameliorates serum lipoprotein functions, adipokine profile and subclinical atherosclerosis in pre-menopausal women.

BACKGROUND AND AIMS: Low vitamin D (vitD) has been linked to increased cardiovascular (CV) risk, but the effects of vitD supplementation are not clarified. We evaluated the impact of vitD normalization on HDL cholesterol efflux capacity (CEC), which inversely correlates with CV risk, the proatherogenic serum cholesterol loading capacity (CLC), adipokine profile and subclinical atherosclerosis. METHODS AND RESULTS: Healthy premenopausal women with vitD deficiency (n = 31) underwent supplementation. Subclinical atherosclerosis was evaluated by flow-mediated dilation (FMD), pulse wave velocity (PWV) and augmentation index (AIx), measured with standard techniques. HDL CEC and serum CLC were measured by a radioisotopic and fluorimetric assay, respectively. Malondialdehyde (MDA) in HDL was quantified by the TBARS assay. Pre-ß HDL was assessed by 2D-electrophoresis. Serum adipokines were measured by ELISA. VitD replacement restored normal levels of serum 25-hydroxyvitamin D (25OHD) and significantly improved FMD (+4%; p < 0.001), PWV (-4.1%: p < 0.001) and AIx (-16.1%; p < 0.001). Total CEC was significantly improved (+19.5%; p = 0.003), with a specific increase in the ABCA1-mediated CEC (+70.8%; p < 0.001). HDL-MDA slightly but significantly decreased (-9.6%; p = 0.027), while no difference was detected in pre-ß HDL. No change was observed in aqueous diffusion nor in the ABCG1-mediated CEC. Serum CLC was significantly reduced (-13.3%; p = 0.026). Levels of adiponectin were increased (+50.6%; p < 0.0001) and resistin levels were decreased (-24.3%; p < 0.0001). After vitD replacement, an inverse relationship was found linking the ABCA1-mediated CEC with pre-ß HDL (r2 = 0.346; p < 0.001) and resistin (r2 = 0.220; p = 0.009). CONCLUSION: Our data support vitD supplementation for CV risk prevention.

Prevention of cardiovascular disease in rheumatoid arthritis.

The increased risk of cardiovascular disease (CVD) in rheumatoid arthritis (RA) has been recognized for many years. However, although the characteristics of CVD and its burden resemble those in diabetes, the focus on cardiovascular (CV) prevention in RA has lagged behind, both in the clinical and research settings. Similar to diabetes, the clinical picture of CVD in RA may be atypical, even asymptomatic. Therefore, a proactive screening for subclinical CVD in RA is warranted. Because of the lack of clinical trials, the ideal CVD prevention (CVP) in RA has not yet been defined. In this article, we focus on challenges and controversies in the CVP in RA (such as thresholds for statin therapy), and propose recommendations based on the current evidence. Due to the significant contribution of non-traditional, RA-related CV risk factors, the CV risk calculators developed for the general population underestimate the true risk in RA. Thus, there is an enormous need to develop adequate CV risk stratification tools and to identify the optimal CVP strategies in RA. While awaiting results from randomized controlled trials in RA, clinicians are largely dependent on the use of common sense, and extrapolation of data from studies on other patient populations. The CVP in RA should be based on an individualized evaluation of a broad spectrum of risk factors, and include: 1) reduction of inflammation, preferably with drugs decreasing CV risk, 2) management of factors associated with increased CV risk (e.g., smoking, hypertension, hyperglycemia, dyslipidemia, kidney disease, depression, periodontitis, hypothyroidism, vitamin D deficiency and sleep apnea), and promotion of healthy life style (smoking cessation, healthy diet, adjusted physical activity, stress management, weight control), 3) aspirin and influenza and pneumococcus vaccines according to current guidelines, and 4) limiting use of drugs that increase CV risk. Rheumatologists should take responsibility for the education of health care providers and RA patients regarding CVP in RA. It is immensely important to incorporate CV outcomes in testing of anti-rheumatic drugs.

The natural compound berberine positively affects macrophage functions involved in atherogenesis.

BACKGROUND AND AIMS: We investigated the effect of berberine (BBR), an alkaloid showing antiatherogenic properties beyond the cholesterol lowering capacity, on macrophage cholesterol handling upon exposure to human serum and on macrophage responses to excess free cholesterol (FC) loading. METHODS AND RESULTS: Mouse and human macrophages were utilized as cellular models. Cholesterol content was measured by a fluorimetric assay; cholesterol efflux, cytotoxicity and membrane FC distribution were evaluated by radioisotopic assays. Monocyte chemotactic protein-1 (MCP-1) secretion was measured by ELISA; membrane ruffling and macropinocytosis were visualized by confocal microscopy. Exposure of cholesterol-enriched MPM to serum in the presence of 1 µM BBR resulted in a reduction of intracellular cholesterol content twice greater than exposure to serum alone (-52%; p < 0.01 and -21%; p < 0.05), an effect not mediated by an increase of cholesterol efflux, but rather by the inhibition of cholesterol uptake from serum. Consistently, BBR inhibited in a dose-dependent manner cholesterol accumulation in human macrophages exposed to hypercholesterolemic serum. Confocal microscope analysis revealed that BBR inhibited macropinocytosis, an independent-receptor process involved in LDL internalization. Macrophage FC-enrichment increased MCP-1 release by 1.5 folds, increased cytotoxicity by 2 fold, and induced membrane ruffling; all these responses were markedly inhibited by BBR. FC-enrichment led to an increase in plasma membrane cholesterol by 4.5 folds, an effect counteracted by BBR. CONCLUSION: We showed novel potentially atheroprotective activities of BBR in macrophages, consisting in the inhibition of serum-induced cholesterol accumulation, occurring at least in part through an impairment of macropinocytosis, and of FC-induced deleterious effects.

Cellular cholesterol efflux and cholesterol loading capacity of serum: effects of LDL-apheresis.

High LDL-cholesterol (LDL-C) characterizes familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCH). LDL-apheresis, used in these patients to reduce LDL-C levels, has been shown to also affect HDL levels and composition. We studied LDL-apheresis effects on six FH and nine FCH subjects' serum capacity to modulate cellular cholesterol efflux, an index of HDL functionality, and to load macrophages with cholesterol. Serum cholesterol efflux capacity (CEC) and macrophage cholesterol loading capacity (CLC) were measured before, immediately after, and two days after LDL-apheresis. The procedure reduced total cholesterol (TC), LDL-C, and apoB plasma levels (-69%, -80% and -74%, respectively), parameters only partially restored two days later. HDL-C and apoA-I plasma levels, reduced after LDL-apheresis (-27% and -16%, respectively), were restored to almost normal levels two days later. LDL-apheresis reduced serum aqueous diffusion (AD) CEC, SR-BI-CEC, and ABCA1-CEC. AD and SR-BI were fully restored whereas ABCA1-CEC remained low two days later. Sera immediately and two days after LDL-apheresis had a lower CLC than pre-LDL-apheresis sera. In conclusion, LDL-apheresis transiently reduces HDL-C levels and serum CEC, but it also reduces also serum capacity to deliver cholesterol to macrophages. Despite a potentially negative effect on HDL levels and composition, LDL-apheresis may counteract foam cells formation.

Molecular epidemiology of drug-resistant Salmonella Typhimurium in Spain.

One hundred and forty-seven Salmonella serotype Typhimurium strains isolated in three provinces in the midwest of Spain were studied. Of these, 93.6% were drug resistant. There were two predominant resistance phenotypes: 43 isolates (29.3%) were resistant to amoxicillin, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole and 27 isolates (18.4%) to amoxicillin, amoxicillin/clavulanic acid, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole. Randomly amplified polymorphic DNA (RAPD) analysis and pulsed field gel electrophoresis (PFGE) were performed for molecular typing. Thirty-six DNA band profiles were differentiated by RAPD, and 38 by PFGE. We found a high level of clonality; 27% of strains were identical by both methods. There were additional smaller clonal lines within every area. The highest discriminatory power was obtained with PFGE, but the greatest degree of genetic diversity was observed among Salmonella Typhimurium using both RAPD and PFGE.

Normal human IgG prevents endothelial cell activation induced by TNFalpha and oxidized low-density lipoprotein atherogenic stimuli.

Normal human immunoglobulin G (IgG) has anti-inflammatory and immuno-regulatory properties, which are exploited in the therapy of selected diseases. A putative mechanisms of action is the direct regulation of endothelial cell function by natural antiendothelial cell antibodies. Endothelium activation is a critical event in atherosclerosis. We have verified the ability of normal human IgG to modulate endothelial responses to the atherogenic stimuli tumour necrosis factor-alpha (TNFalpha) and oxidized low-density lipoproteins (oxLDL) in vitro. Confocal microscopy was used to visualize vascular cell adhesion molecule-1 (CD106) expression on endothelial cells, cytoplasmic free calcium ([Ca++]i) modifications and fluorescein-coupled oxLDL internalization. Cytokine secretion was measured by ELISA on cell supernatants. IgG prevented TNFalpha induced CD106 membrane expression and an increase in [Ca++]i, and inhibited the secretion of interleukin-6 (IL-6) and macrophage-colony-stimulating factor (M-CSF). IgG also inhibited CD106 expression induced by oxLDL and one pathway of their internalization, but were ineffective on oxLDL induced [Ca++]i rise and apoptosis. F(ab)'2 fragments from IgG, but not monoclonal IgG, reproduce IgG effects. These findings point to a regulatory role for specific antibodies included in circulating normal IgG towards proinflammatory responses of endothelial cells in atherogenesis and suggest possible development of new therapeutic strategies.

Natural anti-endothelial cell antibodies (AECA).

Natural AECA constitute a pool of autoantibodies circulating in healthy subjects, which react with a restricted and conserved set of endothelial antigens and establish idiotypic interactions within the immunoglobulin networks. Normal IgG interacts with living endothelial cells and is internalized with a mechanism involving microtubules and resembling that of ligand-receptor internalization. IgG-endothelial cell interaction appears to be dependent on the variable region of antibodies and is followed by modifications of endothelial cell function. Natural AECA increase anti-inflammatory properties of endothelial cells through the selective inhibition of thromboxane A2, endothelin and metalloproteinase-9 secretion, and also through the inhibition of endothelial cell proinflammatory response to TNF-alpha. We have gathered evidence demonstrating that natural AECA constitute a strictly controlled autoantibody pool, interact with living endothelial cells and take part in the regulation of endothelial function, through direct anti-inflammatory effects.

Binding and internalization of human IgG by living cultured endothelial cells.

Interactions between circulating IgG and endothelial cells (EC) in humans have been described only in conditions associated with pathologic immunoglobulins and/or activated or damaged EC. In this study we provide evidence that normal human IgG includes one/some antibody species that bind to and are internalized by living EC in culture. This novel function of EC and natural autoantibodies is of potential importance for the understanding of physiologic interactions between vessels and the immune system and for the clarification of pathogenesis of vasculitis and mechanisms of action of pooled IgG used in the therapy of such conditions.

Normal human polyspecific immunoglobulin G (intravenous immunoglobulin) modulates endothelial cell function in vitro.

We have analysed the in-vitro effect of pooled normal polyspecific immunoglobulin G (IVIg) and F(ab')2 fragments of IVIg on the secretion of prostacyclin (PGI2), thromboxane A2 (TxA2), and endothelin from cultured human umbilical vein endothelial cells. The stable metabolites, 6-keto-PGF1 alpha and TxB2, as well as endothelin, were measured by radioimmunoassay after extraction from the culture supernatants. IVIg inhibited TxB2 and endothelin secretion in a dose-dependent manner, but not that of 6-keto-PGF1 alpha. Therefore the ratio of 6-keto-PGF1 alpha/TxB2 increased (+600%). The effect of F(ab')2 fragments prepared from IVIg was similar to that observed with IVIg, indicating that the effect of IVIg was mediated by the variable region of immunoglobulin. The results suggest that part of the effects of IVIg in inflammatory vasculitis may be due to a modification of the PGI2/TxA2 ratio and inhibition of endothelin secretion, and that natural IgG antibodies may participate in the homeostatic process of endothelium under physiological conditions.

Analysis of natural and disease-associated autoantibody repertoires: anti-endothelial cell IgG autoantibody activity in the serum of healthy individuals and patients with systemic lupus erythematosus.

The present study demonstrates that natural IgG with anti-endothelial cell activity is present in the serum of healthy individuals and in pooled normal human Ig. By using a novel method that allows for the simultaneous and quantitative assessment of reactivities of antibodies with a large number of antigens in tissues, we observed that natural anti-endothelial cell antibody (AECA) recognizes a restricted set of self antigens in endothelial cells that is conserved among healthy individuals. The extent to which natural AECA activity is expressed in serum and the pattern of reactivity of AECA with endothelial cell antigens showed little variability between individuals. Analysis of AECA in the serum of patients with systemic lupus erythematosus (SLE) revealed a higher amount of activity and a wider spectrum of antigenic specificities than that recognized by natural antibodies in endothelial cell extracts. AECA activity of IgG in whole serum was lower than that of purified IgG in the case of healthy individuals and showed little variation among individuals. In contrast, no difference was found between AECA activity of purified IgG and that of IgG in patients' serum suggesting that SLE sera lack the factors that control expression of AECA activity in the serum of healthy individuals. Our results indicate that natural autoantibodies recognize a restricted and conserved set of self antigens. Our observations further suggest that defective regulation of the expressed autoreactive B cell repertoire is the basis for expansion of novel clonal specificities and enhanced autoantibody activity in serum of patients with autoimmune disease.

Selectivity of recognition of variable (V) regions of autoantibodies by intravenous immunoglobulin (IVIg).

In the present study, we demonstrate that intravenous immunoglobulin (IVIg) is capable of binding to variable (V) regions of anti-endothelial cell antibodies (AECA) of healthy donors and patients with systemic lupus erythematosus (SLE). Among V regions of AECAs, IVIg selectively recognized certain idiotypes expressed by the autoantibodies of a given individual, in the case of both natural and SLE-associated AECAs. These observations provide new and direct evidence that IVIg interacts idiotypically with V regions of autoantibodies and that the efficacy of such interaction depends on individual autoantibody specificity. Our findings may be relevant for the understanding of the mechanisms that control expression of natural autoantibody activity in serum and for that of the differences in response to IVIg therapy that are seen between patients with autoimmune disease.

Antineutrophil cytoplasm antibodies (ANCA) of IgA isotype in adult Henoch-Schönlein purpura.

ANCA are associated with certain forms of systemic vasculitis, and have been reported previously to be of the IgG and IgM isotype. We examined the possible association between IgA ANCA and the IgA-related diseases Henoch-Schönlein purpura (HSP) and IgA nephropathy (IgAN). IgA and IgG ANCA were detected by isotype-specific solid-phase assays with a crude neutrophil extract, and their presence was confirmed by antigen-specific fluid-phase competitive inhibition tests and by indirect immunofluorescence. The possible interference by IgA rheumatoid factor was excluded. IgA ANCA were detected in sera from 11/14 HSP patients (79%), from 1/30 IgAN patients (3%), from 1/40 patients with vasculitides classically associated with IgG ANCA (2.5%), and in none of 60 sera from healthy blood donors. IgG ANCA were present with IgA ANCA in three patients with HSP. Only one HSP serum had anti-myeloperoxidase (MPO) activity by both IgA and IgG isotype-specific ELISA, and none was positive for proteinase 3 (PR3). Western blot analysis performed with neutrophil extract showed that the four strongest IgA ANCA-positive HSP sera reacted with a 51-kD protein; Western blot performed on cellular fractions showed that this protein is primarily membrane-associated, and different from fibronectin. Our study suggests that adult HSP is closely associated with circulating IgA ANCA, which may be directed against a different autoantigen than that recognized by IgG ANCA.