Selective deposition of immunoglobulin A1 in immunoglobulin A nephropathy, anaphylactoid purpura nephritis, and systemic lupus erythematosus

To further characterize the IgA deposits found in glomeruli of patients with IgA nephropathy, anaphylactoid purpura nephritis, and systemic lupus erythematosus, renal biopsies from patients with these disorders were stained by immunofluorescence with monoclonal anti-IgA subclass reagents, anti-light chain reagents and anti-J chain. The mesangium and peripheral capillary were brightly stained for IgA1 and were negative for IgA2. IgA1 and, to a lesser extent, IgA2 were contained in tubular casts. Both kappa and lambda light chains were found in all deposits. The intensity of J chain staining correlated with the intensity of IgM and not IgA staining. Biopsies brightly stained for IgA but negative for IgM were negative for J chain. These results indicate that glomerular IgA deposits in these disorders consist predominantly of monomers of IgA1.

What is the difference between IgA nephropathy and Henoch-Schönlein purpura nephritis?

Henoch-Schönlein purpura nephritis (HSPN) and IgA nephropathy (IgAN) are considered to be related diseases since both can be encountered consecutively in the same patient, they have been described in twins, and bear identical pathological and biological abnormalities. Apart from the presence of extrarenal clinical signs found only in HSPN, other differences are noticed between the two diseases. The peak age ranges between 15 and 30 years for a diagnosis of IgAN, whereas HSPN is mainly seen in childhood. Nephritic and/or nephrotic syndromes are more often seen at presentation in HSPN. In contrast to IgAN, HSPN has been described in association with hypersensitivity. Endocapillary and extracapillary inflammations as well as fibrin deposits in the glomerulus are more frequent in HSPN. No major biological differences have been found between the two illnesses, except for a larger size of circulating IgA-containing complexes (IgA-CC) and a greater incidence of increased plasma IgE levels in HSPN. As tissue infiltration by leukocytes is a major feature of HSPN vasculitis, a possible role of a more potent activation of the latter cells by IgA-CC and/or circulating chemokines in HSPN should be considered. Further studies are required to elucidate this possible mechanism as well as the role of hypersensitivity in HSPN.

Immunologic studies in IgA nephropathy

Circulating immune complexes (CIC) were detected in 43.6% of 78 patients with primary IgA nephropathy by the solid-phase Clq radioimmunoassay. The IC were intermediate (9 to 17S) in size and contained IgA, IgG, and less commonly IgM. CIC were often present intermittently, correlating with episodes of macroscopic hematuria. Elevated serum IgA concentrations (38.7%) did not correlate with the detection of CIC. Similar findings were observed in sera samples from patients with Henoch Schonlein purpura and in IgA glomerulonephritis associated with alcoholic cirrhosis and/or portal systemic shunts. The factors responsible for the mesangial localization of the IC are not clear, but elevations in serum antibody titers to respiratory pathogens (mycoplasma pneumoniae, herpes virus, influenza), gut flora (E. coli 07), and bovine serum albumin suggest that common exogenous antigens may be involved in the pathogenesis. Primary defects in either mucosal antigen exclusion or reticuloendothelial IC sequestration are proposed to account for these findings.

IgA immune complexes in Henoch-Schönlein purpura

Raised levels of IgA immune complexes were found in 13 of 18 children with Henoch-Schönlein purpura irrespective of whether they developed nephritis or not. In contrast, only those children who developed nephritis had raised levels of IgG immune complexes as well. In 2 children with nephritis, two discrete peaks of IgA complexes were found, corresponding to 4 x 10(5) to 8 x 10(5) and 2.5 x 10(6) to 4 x 10(6) daltons. IgG complexes were found only in the larger-molecular-weight peak. Such differences in immune complexes may underlie the different manifestations of this disease.

Henoch-Schönlein Purpura: A Literature Review

Henoch-Schönlein purpura is the most common childhood vasculitis, but may also affect adults. This article reviews the literature since 2011 on advances in diagnosis, clinical disease manifestations, pathophysiology and treatment of Henoch-Schönlein purpura. The clinical manifestations are thought to arise from IgA depositions in blood vessel walls in the affected organs, mostly skin, gastrointestinal tract, joints and kidneys. Corticosteroids may be effective in rapid resolution of renal manifestations and treating joint and abdominal pain, but they are not proven effective for treating organ manifestations and complications, such as glomerulonephritis, bowel infarction or intussusception. Mycophenolate mofetil or cyclosporine A may be better treatment choices in case of renal involvement. Other immunosuppressive and immunomodulating drugs, such as rituximab and dapsone, are promising, but larger studies are needed to confirm these findings. Cancer screening should be considered in older males diagnosed with Henoch-Schönlein purpura.

Henoch-Schönlein purpura

Although Henoch-Schönlein purpura (HSP) can occur at any age from infancy to adulthood, it is overwhelmingly a disease of childhood. Indeed, HSP is the most common vasculitis syndrome affecting children. The clinical features of HSP have been well documented, and the diagnosis is generally not difficult. However, there are substantial gaps in our understanding of the etiology, pathogenesis, and treatment of HSP. This article briefly reviews the clinical aspects of HSP and new information concerning therapy. The major focus of this review is recent information concerning abnormalities of immunoglobulin A1 glycosylation and the role of aberrantly glycosylated immunoglobulin A1 in the pathogenesis of HSP.

Postinfectious purpura fulminans caused by an autoantibody directed against protein S

OBJECTIVE

To determine the mechanism responsible for idiopathic purpura fulminans, we investigated the procoagulant and anticoagulant pathways in five consecutive patients, four after varicella, and the fifth after a nonspecific infection.

METHODS

Procoagulant and anticoagulant factors, including protein C, protein S, and antithrombin III, were measured by quantitative or functional assays. Anti-protein S autoantibodies were identified by dot blotting and Western blotting, and quantified serially by enzyme-linked immunosorbent assay. Clinical and laboratory data were collated retrospectively.

RESULTS

In each case the disease began 7 to 10 days after the onset of the precipitating infection, with rapidly progressive purpura leading to extensive areas of skin necrosis. The illness was complicated by impaired perfusion of limbs or digits (two patients), peripheral gangrene resulting in an above-knee amputation (one patient), and major organ dysfunction caused by thromboembolic phenomena involving the lungs (two patients), the heart (one patient), or the kidneys (one patient). Protein S levels were virtually undetectable at the time of admission and failed to respond to infusions of fresh frozen plasma, despite correction of other procoagulant and anticoagulant factors. All five children had anti-protein S IgM and IgG autoantibodies, which persisted for less than 3 months after admission. Decline in the anti-protein S IgG antibody concentration was associated with normalization of the plasma protein S levels.

CONCLUSIONS

Autoimmune protein S deficiency may be a common mechanism causing postinfectious idiopathic purpura fulminans. Recognition of the pathophysiologic mechanism may provide a rational basis for treatment. Immediate heparinization, infusions of fresh frozen plasma, and, in cases complicated by major vessel thrombosis, the use of tissue-type plasminogen activator may limit thromboembolic complications.

Circulating IgA-immune complexes in Henoch-Schönlein purpura. A longitudinal study of their relationship to disease activity and vascular deposition of IgA

In Henoch-Schönlein purpura immune complexes in inflamed vessel walls characteristically contain immunoglobulin A(IgA). To determine whether IgA is also the predominant immunoglobulin in circulating immune complexes, we compared the results of three immune complex assays with specificities for different classes of immunoglobulins in a longitudinal study of 37 patients (30 children and seven adults) with Henoch-Schönlein purpura. Circulating IgA-containing immune complexes were detected by their reactivity with a low avidity anti-IgA antibody in 27 of the 37 patients. IgA was simultaneously present in cutaneous vessel walls in 95 percent of the patients with circulating IgA-containing immune complexes. High levels of IgA-containing immune complexes were found only during the initial phase of the disease. Immune complexes containing bound complement breakdown products were demonstrated by binding to conglutinin. IgA was found in these immune complexes in 17 patients, IgG in 17 and IgM in nine patients. There was no apparent relation with the class of immunoglobulin in the deposits. Conglutinin-binding immune complexes were present later in the course of the disease and after remission. C1q-binding immune complexes were only found in two patients. These findings suggest that immune complexes-containing IgA may initiate the vasculitis of Henoch-Schönlein purpura, whereas complement-reacted immune complexes containing immunoglobulins of the other classes appear in the circulation in a later phase.

Occurrence of vascular IgA deposits in clinically normal skin of patients with renal disease

Skin and kidney biopsies were performed on 262 patients with various nephropathies. In 45 skin biopsy specimens finely granular deposits of predominantly IgA and late-acting complement factors were detected in the walls of superficial capillaries, sometimes concomitantly with IgM, IgG, C4 or a combination of these proteins. Twelve of the 45 patients presented with anaphylactoid purpura and the majority of the other 33 patients had either recurrent macroscopic or microscopic hematuria. The renal lesions in 32 of these 45 patients consisted of focal segmental intracapillary proliferation. In 35 the kidney biopsy specimen showed mesangial deposits of IgA; in one case IgA was deposited along the glomerular basement membrane. In only three of the remaining 217 patients without cutaneous IgA deposits were typical mesangial IgA deposits found. The close correlation between IgA deposits in cutaneous vessels and focal segmental intracapillary proliferation with mesangial IgA deposits suggests that immunofluorescence examination of skin biopsy specimens could prove of diagnostic value. The results provide additional evidence for a close pathogenic relationship between IgA-associated glomerulonephritis and anaphylactoid purpura.

Activated complement C3: a potentially novel predictor of progressive IgA nephropathy

In the search for a serologic marker of disease activity, we measured concentrations of activated C3 (actC3, that is, neoantigens developing after C3 activation on breakdown products), C4-C3 complexes and soluble C5b-9 (sC5b-9) in one or two plasma samples from adult patients with IgA nephropathy (IgAN, N = 50) or Henoch-Schönlein purpura (HSP, N = 4). As controls, 20 patients with non-immune renal disease, but comparable age, degree of proteinuria, renal dysfunction and prevalence of hypertension were studied. Compared to controls, actC3 levels were elevated in 30% of the patients with IgAN and one of the HSP patients. C4-C3 complexes were elevated in only 8% of the IgAN patients, and sC5b-9 levels were within the control range in all IgAN and HSP patients. In IgAN patients with elevated actC3 levels, proteinuria and hematuria were more pronounced than in those with normal levels. Elevated plasma concentrations of actC3 at the first presentation correlated with subsequent deterioration of renal function both in patients with initially normal and already impaired renal function (r = -0.56, N = 44, P = 0.003). The five IgAN patients with elevated actC3 on both occasions of obtaining plasma showed the most rapid loss of renal function. We conclude that mainly alternative pathway complement activation can be demonstrated in patients with IgAN and HSP. In IgAN patients the presence of complement activation is associated with more severe renal disease. Further studies are warranted to examine the clinical usefulness of actC3 as a predictor of the subsequent course of IgAN.

Is there a crossroad between infections, genetics, and Henoch-Schönlein purpura?

Henoch-Schönlein purpura is the most common systemic vasculitis in childhood, characterized by the presence of immunoglobulin A deposits in the small vessels of skin, gastrointestinal tube, joints and kidneys. Although there have been great efforts made in elucidating its pathogenic mechanisms, Henoch-Schönlein purpura etiology remains unknown: the basic scene comes across an abnormal inflammatory process deriving from immune reactions to various antigenic stimuli, which might be bacterial, viral, or parasitic agents, in a genetically prone individual. Then, a peculiar immune complex deposition in the vascular walls and overproduction of different proinflammatory molecules elicit different clinical signs, which might be differentiated according to either a specific trigger or a specific genetic make-up. The aim of this review is to make a critical appraisal of the last 15years' medical literature concerning the relationship between infections, genetics, and Henoch-Schönlein purpura in pediatrics.

Acute hemorrhagic edema of infancy (AHEI)--a variant of Henoch-Schönlein purpura or a distinct clinical entity?

Acute hemorrhagic edema of infancy (AHEI) is an acute cutaneous leukocytoclastic vasculitis (LCV) of infants. The clinical picture has a violent onset with a short benign course followed by spontaneous complete recovery. We report 12 infants with AHEI who were studied clinically, serologically, and immunohistologically. Edema and palpable purpuric skin lesions were present in all infants who were in good general condition. Serologic studies were unremarkable. Light microscopic examination of the skin biopsy specimens revealed LCV as in Henoch-Schönlein purpura (HSP). Direct immunofluorescent study revealed depositions of various immunoreactants, including fibrinogen, C3, IgG, IgM, IgA, and IgE (100%, 100%, 22%, 78%, 33%, and 33%, respectively) in the wall and around the small vessels. Similar deposition of Clq was also present in three infants in whom Clq could be studied (100%). The clinical similarities and differences between AHEI and HSP have been discussed in the literature. AHEI is observed before 2 years of age and is confined to the skin. The skin lesions of HSP are more polymorphic. Although histopathologic findings are similar, the immunohistologic pattern found in our series of AHEI is rather different from the pattern of HSP. Taking all of these findings into account, we suggest that AHEI should be considered as a separate, clinicopathologic entity or a possible variant of HSP. The more descriptive term "acute benign cutaneous LCV of infancy" is offered for this clinicopathologic entity.

CD14+CD16+ monocyte subpopulation in Kawasaki disease

Kawasaki disease (KD) is an acute febrile illness caused by vasculitis, occurring in early childhood. We have demonstrated that the activation of monocytes/macrophages plays a central role during acute KD. Recently, it has been reported that the CD14+CD16+ monocyte subpopulation plays a more important role in inflammation. In this study, we investigated the peripheral blood CD14+CD16+ monocyte subpopulation by flow cytometry, and serum levels of IL-10 and IL-12 using a sandwich ELISA in 28 KD patients. We also investigated this subpopulation in patients with bacterial infections, mononucleosis and anaphylactoid purpura, since the cause of KD remains unknown. We observed an increase in the number of CD14+CD16+ monocytes with acute KD, which was a positive correlation with C-reactive protein levels, and we observed only the patients with severe bacterial infections had increased this subpopulation during the acute stage among control diseases. In addition, we found that the serum levels of IL-10, but not IL-12, were higher during acute KD. These data suggest that increased peripheral blood CD14+CD16+ monocytes are part of the regulatory system of monocyte function during acute KD.

IgA nephropathy and Henoch-Schoenlein purpura nephritis: aberrant glycosylation of IgA1, formation of IgA1-containing immune complexes, and activation of mesangial cells

IgA1 in the circulation and glomerular deposits of patients with IgA nephropathy (IgAN) is aberrantly glycosylated; the hinge-region O-linked glycans are galactose-deficient. The circulating IgA1 of patients with Henoch-Schoenlein purpura nephritis (HSPN) has a similar defect. This aberrancy exposes N-acetylgalactosamine-containing neoepitopes recognized by naturally occurring IgG or IgA1 antibodies resulting in formation of immune complexes. IgA1 contains up to six O-glycosylation sites per heavy chain; it is not known whether the glycosylation defect occurs randomly or preferentially at specific sites. We sought to define the aberrant glycosylation of a galactose-deficient IgA1 myeloma protein and analyze the formation of the immune complexes and their biological activities. Supplementation of serum or cord-blood serum with this IgA1 protein resulted in formation of new IgA1 complexes. These complexes stimulated proliferation of cultured human mesangial cells, as did the naturally-occurring IgA1-containing complexes from sera of patients with IgAN and HSPN. Uncomplexed IgA1 did not affect cellular proliferation. Using specific proteases, lectin Western blots, and mass spectrometry, we determined the O-glycosylation sites in the hinge region of the IgA1 myeloma protein and IgA1 proteins from sera of IgAN patients. The IgA1 myeloma protein had galactose-deficient sites at residues 228 and/or 230 and 232. These sites reacted with IgG specific to galactose-deficient IgA1. IgA1 from the IgAN patients had galactose-deficient O-glycans at the same residues. In summary, we identified the neoepitopes on IgA1 responsible for formation of the pathogenic immune complexes. These studies may lead to development of noninvasive diagnostic assays and future disease-specific therapy.

The role of cytokines in Henoch Schonlein purpura

Serum levels of tumor necrosis factor (TNF) and interleukin(IL-1) were studied in 20 HSP patients, in the acute phase and after remission, by ELISA technique. Skin biopsies obtained during the acute phase both from a lesion and from unaffected skin, as well as during remission, were immunostained for TNF, IL-1, and IL-6. The mean age of the patients was 9.8 (5-13). Mean serum TNF levels during the acute phase and remission were 14.0 +/- 8.9 pg/ml, and 6.8 +/- 2.4 pg/ml, respectively (p < 0.05). Serum TNF levels in patients with renal involvement (18.8 +/- 10.2 pg/ml) were significantly higher than in those without (10.8 +/- 6.5 pg/ml) (p < 0.05). Serum levels of IL-1 in the acute phase and remission were undetectable. All specimens showed leukocytoclastic vasculitis. Immunohistochemical studies revealed TNF, and a less intense IL-1 and IL-6 staining in the nucleated epidermal layer, with a granular, intracellular pattern. Staining was significantly increased in the affected skin during the acute phase. These results suggest that TNF, IL-1, and IL-6 may play a role as a mediator of inflammation in HSP.

Effectiveness of early prednisone treatment in preventing the development of nephropathy in anaphylactoid purpura

A prospective study was performed to verify whether early administration of prednisone could be useful in preventing the development of nephropathy in anaphylactoid purpura. Only patients without signs of nephropathy upon initial presentation entered into the study. A total of 84 patients received delta-prednisone (1 mg/kg per day per os for 2 weeks), and 84 patients did not receive steroids. The patients were followed for 24-36 months. None of the 84 patients treated with steroids and 10 (11.9%) of the 84 control patients developed nephropathy 2-6 weeks after the acute episode. In 2 other patients of the untreated group, signs of renal involvement appeared 2 and 6 years after the acute episode respectively. The difference in the prevalence of nephropathy between the two groups is highly significant (P less than 0.001).

Anti-alpha-galactosyl antibodies and immune complexes in children with Henoch-Schönlein purpura or IgA nephropathy

Episodes of hematuria in IgA nephropathy or Henoch-Schönlein purpura are frequently associated with microbial infections. Some of those infectious agents bear alpha-galactosyl residues on their cell surface. These observations prompted us to determine, by passive hemagglutination, the titers of natural anti-galactosyl antibodies in the serum of children presenting with Henoch-Schönlein purpura (10 cases) or IgA nephropathy (7 cases). Antibody titers of normal subjects (103 cases), children with a pharyngitis of unknown etiology (7 cases), and children exhibiting mesangial IgA deposits but no hematuria at the time of testing (6 cases) ranged from 1:20 to 1:80. Elevated titers (greater than 1:80) were observed in nine of 11 patients with mesangial IgA deposits and micro- or macroscopic hematuria, in nine of 19 children with other evolutive glomerular diseases (5 cases of acute glomerulonephritis and 4 cases of minimal change disease), and in most subjects presenting with a M. pneumoniae (4/5 cases) or a E. Coli (4/5 cases) infection. Antibody titers decreased after incubation of normal and pathological sera with D-galactose (10 mM) or with alpha-galactosyl-glucoside (10 mM), but not with D-glucose (10 mM). The anti-alpha-galactosyl antibodies purified, by affinity chromatography, from sera of 10 normal children, 10 pathological controls and four children with mesangial IgA deposits without hematuria belonged to IgG class. In contrast, both IgG and IgA anti-alpha-galactosyl antibodies were detected in six of six patients with mesangial IgA deposits and hematuria. The IgA content of immune complexes detected in those patients decreased after incubation of sera with alpha-galactosyl-glucoside, but not with D-glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

The level of IgA antibodies to human umbilical vein endothelial cells can be enhanced by TNF-alpha treatment in children with Henoch-Schönlein purpura

Anti-endothelial cell antibodies (AECA) have been found to play an important role in many vascular disorders. In order to determine the presence of AECA in children with Henoch-Schönlein purpura (HSP), and to elucidate the pathogenic and clinical value of their measurement in this disease, AECA were detected by immunofluorescence staining and a human umbilical vein endothelial cell (HUVEC)-based enzyme-linked immunosorbent assay (ELISA) in 20 children with HSP, 10 children with juvenile rheumatoid arthritis (JRA) without vasculitis and 10 normal healthy children. Antibodies against another endothelial cells, human dermal microvascular endothelial cells (HMVEC-d) were also detected by cell-based ELISA. In some experiments, we compared the binding activity of antibodies to HUVEC with and without tumour necrosis factor-alpha (TNF-alpha) or interleukin-1 (IL-1) pretreatment. Patients with acute onset of HSP had higher serum levels of IgA antibodies, both against HUVEC and against HMVEC-d, than healthy controls (P = 0.001, P = 0.008, respectively). Forty-five per cent of patients had positive IgA AECA to HUVEC, and 35% had positive IgA AECA to HMVEC-d. The titres of IgA antibodies to HUVEC paralleled the disease activity. After TNF-alpha treatment, the values of IgA AECA to HUVEC in HSP patients were significantly increased (P = 0.02). For IgG and IgM AECA, there was no difference between HSP patients and controls (P = 0.51, P = 0.91). Ten JRA children without vasculitis had no detectable IgG, IgM or IgA AECA activity. The results of this study showed that children with HSP had IgA AECA, which were enhanced by TNF-alpha treatment. Although the role of these antibodies is not clear, IgA AECA provide another immunological clue for the understanding of HSP.

Recurrence of immunoglobulin A nephropathy after renal transplantation in the cyclosporine era

Immunoglobulin A nephropathy (IgAN) frequently recurs in patients after renal transplantation (RT) on a conventional regimen of immunosuppressive therapy, but little is known about the influence of cyclosporine (Cs) on such a recurrence. We studied 84 patients retrospectively who underwent RT for renal failure attributable to IgAN (n = 71) or Henoch-Schönlein purpura nephropathy (HSPN) (n = 13) in two transplantation units, between January 1985 and June 1991 and were treated with Cs. Four patients died 3 months to 8 years after RT. Graft survival was 88% at 1 year, 75.2% at 5 years, and 63% at 8 years. Fifty patients underwent at least one graft biopsy, but studies with immunofluorescence were performed on only 28 (23 IgAN and 5 HSPN). After a mean follow-up of 68.1 +/- 37.2 months, mesangial IgA deposits recurred in 13 of the 28 patients (12 IgAN and 1 HSP) (prevalence, 46.4%). Among the 13 patients with recurrence of IgA deposits, all but 4 had urinary abnormalities. Light microscopy showed mesangial deposits and focal and segmental glomerular changes in 9 cases. Four patients lost their graft function 69 to 119 months after RT, and 2 had severe graft dysfunction. The rates of graft failure and mean serum creatinine at 1, 5, and 8 years were similar in the 13 patients with recurrence and the 15 patients without proven recurrence. In conclusion, Cs did not reduce the incidence or severity of IgAN recurrence. The latter was the cause of graft loss or dysfunction in 46.1 % of the patients with recurrent IgA deposits. Recurrent glomerulonephritis did not influence the 8-year graft survival in patients with IgAN or HSPN, but it may be an important cause of graft loss as evidenced by more extended follow-up.

Schönlein-Henoch syndrome in patients with familial Mediterranean fever

Ten episodes of Schönlein-Henoch purpura (SHP) in 8 patients with familial Mediterranean fever (FMF) were observed. Five episodes developed 3-14 days after penicillin injections, suggesting an etiologic association. FMF and SHP have clear clinical similarities, and if the frequency of association of the 2 diseases is indeed high, perhaps a common etiologic factor should be sought. An immune complex mechanism might be the link between these 2 disease entities.

A clinical and histologic study of 37 cases of immunoglobulin A-associated vasculitis

Immunoglobulin (Ig) A-associated vasculitis is commonly equated with the multiorgan systemic vasculitic syndrome Henoch-Schonlein purpura (HSP), which occurs predominantly in the pediatric age group. By natural language search of the databases of two outpatient dermatopathology practices, the authors selected for review 37 cases of IgA-associated vasculitis, 23 of which were associated with antecedent infection, most commonly of the upper respiratory tract. Criteria for a diagnosis of HSP were met in 15 cases, 13 of which were in the setting of prior infection. Lower extremity skin involvement was ubiquitous. A more widespread form of vasculitis was also seen, particularly in the setting of previous infection. Several of the patients with previous infection had underlying medical illnesses including rheumatoid arthritis, atopy, renal failure, lupus erythematosus, insulin dependent diabetes mellitus, autoimmune thyroid disease, and Wegener's granulomatosis. In those patients lacking an apparent microbial trigger, Sjogren's disease with anti-Ro antibodies and hypergammaglobulinemia, lupus erythematosus, inflammatory bowel disease, IgA paraproteinemia, bronchogenic and prostatic carcinoma, cryoglobulinemia, and lymphoma were uncovered. Regardless of whether an infectious stimulus was implicated, certain cofactors with the potential to enhance vascular injury were uncovered; these included anti-Ro antibodies, antineutrophil cytoplasmic antibody, diabetic microangiopathy, and a hyperviscosity state. In the infective group, a pustular vasculitis, defined as a neutrophilic vascular reaction in concert with epithelial pustulation, was seen in 81% of cases versus 33% in the noninfectious group (p = 0.02). The prototypic histomorphology in the noninfective group was one of a mild cell poor leukocytoclastic vasculitis; Vasculitis was of greater severity in patients with antecedent infection (p = 0.026). An infectious trigger, typically of mucosal origin, can frequently be identified in patients with cutaneous IgA-associated vasculitis, especially those with the symptom complex of HSP. The light microscopy appears to distinguish patients who have an infectious trigger from those who do not. IgA-associated vasculitis may be a clue to the presence of certain underlying disorders where there is immune dysregulation or enhanced susceptibility to immune complex entrapment.

Henoch-Schönlein vasculitis: direct immunofluorescence study of uninvolved skin

Henoch-Schönlein purpura is a multisystem disease believed to be a consequence of entrapment of circulating IgA-containing immune complexes in blood vessel walls throughout the skin, kidney, and gastrointestinal tract. In this direct immunofluorescence study, twenty-five skin biopsy specimens from twenty patients with Henoch-Schönlein purpura were examined (9 from uninvolved, normal-appearing skin). A distinct stippled pattern of vascular fluorescence was found in 87% of lesion biopsies; 75% of these contained deposits of IgA. In uninvolved skin, seven (78%) showed immunoglobulin in vessel walls and six (67%) contained IgA, suggesting that immune complexes are deposited with equal frequency in normal-appearing and lesional skin of patients with Henoch-Schönlein purpura. Biopsy of uninvolved, rather than of purpuric, skin for direct immunofluorescence studies may be more helpful in confirming the diagnosis of Henoch-Schönlein purpura because tissue morphology is usually of better quality.