Human necrotizing vasculitis: immunoglobulins and complement in vessel walls of cutaneous lesions and normal skin

Galactose-deficient IgA1 in skin and serum from patients with skin-limited and systemic IgA vasculitis

BACKGROUND

IgA vasculitis (IgAV) encompasses a systemic form involving kidneys, gut, skin, or joints, and a skin-limited form. One characteristic feature of systemic IgAV is deposition of galactose-deficient IgA1 (GD-IgA1) in kidneys (as in IgA nephropathy). The relevance of GD-IgA1 for cutaneous vasculitis is unknown.

OBJECTIVE

We investigated whether GD-IgA1 is deposited perivascularly in systemic and also skin-limited IgAV and whether its serum levels differ between both forms.

METHODS

In a case-control study, deposition of GD-IgA1 was analyzed immunohistochemically by KM55 antibody in skin biopsy specimens from 12 patients with skin-limited IgAV and 4 with systemic IgAV. GD-IgA1 levels were compared by enzyme-linked immunosorbent assay in sera from 15 patients each with skin-limited and systemic IgAV and from 11 healthy individuals.

RESULTS

All biopsy samples from systemic IgAV, and also from skin-limited IgAV, revealed perivascular GD-IgA1 deposition. The average GD-IgA1 concentration in serum was significantly higher in systemic IgAV than in skin-limited IgAV, despite overlap between the groups.

LIMITATIONS

Although high GD-IgA1 levels may be predictive of systemic IgAV, patient numbers were too low to determine cutoff values for systemic versus skin-limited IgAV.

CONCLUSION

Perivascular GD-IgA1 deposition is a prerequisite for systemic and skin-limited IgAV; however, high GD-IgA1 levels in some patients with systemic IgAV suggest a dose-dependent effect of GD-IgA1 in IgAV.

PITYRIASIS LICHENOIDES ET VARIOLIFORMIS ACUTA IMMUNOHISTOPATHOLOGIC STUDY*

Immunoglobulin M and complement (Clq, C3 and C9) were found to be deposited together in the walls of affected blood vessels and also in the basement membrane zone of skin lesions from two patients with pityriasis lichenoides et varioliformis acuta (PLVA). The fluorescence appeared to be most intensely distributed in blood vessels which were affected by inflammatory infiltrates and frequently showed hyaline or fibrinoid changes of their walls. Deposits of C3 activator, fibrin and albumin were not observed. These findings suggest that the disease process in PLVA is the result of a vasculitis mediated by an immune complex and possibly by activation of the classical complement pathway. In addition, serum IgM was slightly increased in both patients.

Direct immunofluorescence in cutaneous vasculitis: experience from a referral hospital in India

Background:

Cutaneous vasculitis is commonly recognized and biopsied, owing to ease of access. Most biopsies are also subjected to direct immunofluorescence (DIF), though the rates of positivity vary. This is an attempt to assess the utility of DIF and glean data that will help optimize the test.

Objective:

To assess the diagnostic utility of DIF in cutaneous vasculitis.

Materials and Methods:

All cases of suspected cutaneous vasculitis submitted for DIF between 2004 and 2010 were included. Clinical data, histopathologic diagnosis, DIF findings and additional tests such as anti nuclear antibody (ANA), anti neutrophil cytoplasmic antibody (ANCA) (where done) were noted.

Results:

There were 198 patients in the study group, with a female predominance. Purpura was the commonest clinical presentation. Extracutaneous involvement was noted in 29% of patients’ i.e., joint pain, abdominal pain and hematuria. Leukocytoclastic vasculitis was the commonest histologic diagnosis. DIF showed an overall positivity of 39% (n = 77) with C3 in 26% (n = 52) and IgA in 23% (n = 46) cases. Forty one cases of suspected Henoch Schonlein Purpura (HSP) showed IgA positivity. The timing of biopsy ranged from <3 days to six months, with 38% being done within seven days. DIF was positive in 86% of biopsies performed within seven days of onset of lesions. Sixty percent of patients with extracutaneous manifestations showed deposits. Vascular deposits were also noted in dermatitis herpetiformis, dematomyositis and prurigo.

Conclusion:

DIF positivity is strongly influenced by the timing of the biopsy and the presence of extracutaneous features. Its clinical value is greatest in patients with HSP, being contributory in 90% of cases. Vascular deposits may be seen in non-vasculitic conditions and need clinicopathologic correlation.

Mast cells in cutaneous allergic vasculitis: a case report

BACKGROUND

The mechanism of cutaneous allergic vasculitis still remains unclear, and to the best of our knowledge, no case has been reported in the literature in which the number of mast cells was examined.

METHODS

A 33-year-old woman, with a past history of allergic rhinitis due to Japanese cedar and Phleum pratense (timothy), presented with a chief complaint of palpable papules on both lower legs in December 2002. On blood examination, peripheral blood eosinophilia was present, but all other examinations for immunologic diseases were negative, including specific IgE. We suspected cutaneous allergic vasculitis and performed skin biopsy.

RESULTS

In December 2002, histological examination of biopsy specimens of the skin lesions showed leukocytoclastic vasculitis. The diagnosis of cutaneous allergic vasculitis was made based on the clinical symptoms and the pathological findings of biopsy specimens. Immunohistochemical staining for human mast cell tryptase using monoclonal antibody against human mast cell tryptase showed an accumulation of mast cells. Treatment with oral corticosteroid resulted in the disappearance of clinical symptoms, and the steroid tapered. A second skin biopsy was performed in June 2005 after informed consent was obtained. Histological examination showed no findings of leukocytoclastic vasculitis, and the number of mast cells had decreased. She has been well without treatment.

CONCLUSIONS

Mast cells may increase in the skin lesion of cutaneous allergic vasculitis.

Cutaneous Vasculitis Update: Diagnostic Criteria, Classification, Epidemiology, Etiology, Pathogenesis, Evaluation and Prognosis

Vasculitis, inflammation of the vessel wall, can result in mural destruction with hemorrhage, aneurysm formation, and infarction, or intimal-medial hyperplasia and subsequent stenosis leading to tissue ischemia. The skin, in part due to its large vascular bed, exposure to cold temperatures, and frequent presence of stasis, is involved in many distinct as well as un-named vasculitic syndromes that vary from localized and self-limited to generalized and life-threatening with multi-organ disease. To exclude mimics of vasculitis, diagnosis of cutaneous vasculitis requires biopsy confirmation where its acute signs (fibrinoid necrosis), chronic signs (endarteritis obliterans), or past signs (acellular scar of healed arteritis) must be recognized and presence of extravascular findings such as patterned fibrosis or collagenolytic granulomas noted. Although vasculitis can be classified by etiology, many cases have no identifiable cause, and a single etiologic agent can elicit several distinct clinicopathologic expressions of vasculitis. Therefore, the classification of cutaneous vasculitis is best approached morphologically by determining vessel size and principal inflammatory response. These histologic patterns roughly correlate with pathogenic mechanisms that, when coupled with direct immunofluorescent examination, anti-neutrophil cytoplasmic antibody (ANCA) status, and findings from work-up for systemic disease, allow for specific diagnosis, and ultimately, more effective therapy. Herein, we review cutaneous vasculitis focusing on diagnostic criteria, classification, epidemiology, etiology, pathogenesis, and evaluation of the cutaneous vasculitis patient.

Diagnostic, prognostic and pathogenic value of the direct immunofluorescence test in cutaneous leukocytoclastic vasculitis

BACKGROUND

No precise studies have been performed on cutaneous leukocytoclastic vasculitis (LV) to establish whether it is better to obtain a skin biopsy from lesional or from perilesional skin for direct immunofluorescence (DIF). There is no agreement on the immunoglobulins most frequently detected and the value of DIF for the classification of cutaneous vasculitis.

METHODS

A prospective study of DIF in lesional and perilesional skin was performed in 50 leukocytoclastic vasculitis patients and 15 nonvasculitis patients.

RESULTS

We detected a higher level of positivity in involved skin than in uninvolved skin for IgG, IgA, IgM, C3 and fibrinogen but not for C1q. In vasculitic patients, IgA was the immunoglobulin most frequently detected in lesional (82%) and perilesional skin (68%), followed by IgM (56 and 34%, respectively) and IgG (20 and 8%, respectively). Only IgA deposits were associated with the diagnosis of vasculitis, with a sensitivity of 82% in lesional and 68% in perilesional skin, and with a specificity of 73 and 66.7%, respectively. The presence of IgA in lesional skin was associated with renal involvement but there was no association with severity. The presence of IgG or IgM, or the absence of IgA in perilesional skin was related to the presence of cryoglobulins. The absence of IgA in lesional and perilesional skin was also related to hepatitis C virus infection.

CONCLUSIONS

DIF findings in involved skin are more closely related to the diagnosis of vasculitis and can give more information about overall renal involvement than findings in uninvolved skin. However, findings in uninvolved skin are more closely related to the pathogenic factors that trigger the development of vasculitis.

Leukocytoclastic vasculitis--correlation between different histologic stages and direct immunofluorescence results

BACKGROUND

Leukocytoclastic vasculitis is a well-known clinico-pathologic entity. A good correlation between clinical and direct immunofluorescence (DIF) findings has been shown only in the early stages of vasculitis. Our purpose was to determine the correlation between different stages of vasculitis, etiology of vasculitis, and DIF findings.

METHODS

Histologic and DIF studies were performed and evaluated from 40 patients with leukocytoclastic vasculitis.

RESULTS

Thirty-seven out of 40 patients (92%) showed positive DIF findings in the blood vessel walls. Eight patients were in the early stage of vasculitis and exhibited deposits mainly of fibrinogen, C3, and IgM. Seventeen patients were at the fully developed vasculitis stage and showed albumin, fibrinogen, and IgG deposits. Fifteen patients were in the late stage of vasculitis and showed deposits of mainly fibrinogen and C3 in the blood vessel walls.

CONCLUSIONS

The present study demonstrates that DIF examination is a very sensitive test in the diagnosis of vasculitis, and can be used in all stages of vasculitis and not only in the early stages as has been shown in previous studies.

Acute haemorrhagic oedema of infancy: a case report

Acute haemorrhagic oedema of infancy (AHOI) is not a clinically well-recognized disease. We present the case of a 10-month-old girl with AHOI, and compare the clinical, histopathological and immunohistological features of this acute purely cutaneous leukocytoclastic vasculitis with those of the more frequent Henoch-Schönlein purpura. AHOI should be regarded as a separate clinicopathological entity for correct prediction of prognosis and prevention of unnecessary treatment.

Clinical analysis of recurrent hypergammaglobulinemic purpura associated with Sjögren syndrome

Recurrent purpuric lesions are occasionally seen in patients with Sjögren syndrome. Hypergammaglobulinemia is one of the underlying precipitating factors of this condition. Clinical and histopathological analyses were performed on 5 cases of hypergammaglobulinemic purpura associated with Sjögren's syndrome, and the effects of immunomodulatory therapy were evaluated with regards to these conditions. Three out of 5 cases were successfully treated with oral gold compound (Auranofin) and one case with a low dose of cyclophosphamide. Episodic purpura subsided two months after initiation of therapy with improved serum IgG levels. Salivary flow and serum amylase levels also improved in some cases. Immunomodulatory therapy may be useful in managing recurrent purpura based on hypergammaglobulinemia associated with Sjögren syndrome.

Local and systemic activation of the whole complement cascade in human leukocytoclastic cutaneous vasculitis; C3d,g and terminal complement complex as sensitive markers

We have studied complement activation both in plasma samples and in lesional skin from patients with leukocytoclastic cutaneous vasculitis (LCV). Enzyme immunoassay (EIA) quantification of the complement activation markers, C3d,g and the terminal complement complex (TCC) in plasma, showed that their levels were significantly increased in 66% and 55% of the patients, respectively (n = 29) compared with healthy controls, whereas the standard measurements of C3, factor B, C1q, C4 and C2 were generally within normal range. Elevations of C3d,g and TCC levels in plasma were significantly correlated. Importantly, a significant correlation was found between the severity of the vasculitis and both C3d,g and TCC plasma levels. Immunofluorescence studies of skin biopsy specimens demonstrated simultaneous presence of perivascular dermal deposits of C3d,g and TCC in lesional skin from 96% and 80% respectively of the patients (n = 25). There was a significant correlation between the intensity of the deposits of both markers. Clusterin, a TCC inhibitory protein, was always found at the same sites of perivascular TCC deposits. Immunofluorescence studies at the epidermal basement membrane zone (BMZ) revealed in each case deposits of C3d,g which were accompanied by TCC deposits in 52% of the biopsy specimens. These data demonstrate that there is a local and systemic activation of the whole complement cascade in human LCV. The presence of both C3d,g and clusterin-associated TCC perivascular deposits suggests an intervention of a regulatory mechanism of local complement activation in LCV. Finally, measurement of plasma C3d,g and TCC appears to be a sensitive indicator of systemic complement activation and disease severity in LCV.

Livedo vasculitis: vasculitis or thrombotic vasculopathy?

Elevated fibrinopeptide A levels, suggestive of a thrombogenic state, were observed in six patients with livedo vasculitis. Serological studies demonstrated normal complement levels, and circulating immune complexes were not identified by standard assays. Morphological studies showed no evidence of immune complex deposition or a neutrophilic vascular reaction. These results support classification of this disorder as a thrombogenic vasculopathy rather than as a small vessel vasculitis. Further investigations into the thrombotic abnormalities underlying this entity are warranted.

Presence and interpretation of vascular immune deposits in human skin: the value of direct immunofluorescence

Direct immunofluorescence investigation of the skin is an easy and valuable technique to establish the diagnosis immune complex vasculitis. Vascular immune deposits can be found in 60-80% of all cases. Absence of vascular immune deposits, however, does not exclude vasculitis per se, since the dynamics of the vasculitic process limit their presence in time. Knowledge of these dynamics is indispensable for both the clinician and the interpreter. Several practical options are discussed that may increase sensitivity. The specificity of vascular immune deposits has become a complex matter. Different immunoglobulin classes have different specificity, indicating that specificity also depends on the relative incidence of individual immunoglobulin classes. Some of these relative incidences seem to have changed over the years. Furthermore, several non-vasculitic diseases and conditions have now been described, that may show fluorescent pictures similar to vasculitis and thus decrease specificity.

Leukocytoclastic vasculitis (anaphylactoid purpura): a unique occurrence in the oral cavity

Leukocytoclastic vasculitis, immune complex disorder (type III), is a skin disease with both an acute form characterized by bullae, vesicles and ulcerations, and a chronic form characterized by petechiae, macules and ulcerations. The disease presents certain systemic features including diffuse or focal glomerulonephritis and renal failure. The histopathologic characteristics of leukocytoclastic vasculitis in the skin appear primarily in small blood vessels and consist of an infiltration of inflammatory cells, leukoclasis, swelling of endothelial cells, occlusion of blood vessels, accumulation of fibrin and fibrinoid degeneration, as well as the presence of immune complexes in and around blood vessel walls. Although leukocytoclastic vasculitis is described as several diseases which can spread systemically, including the gastrointestinal tract and the kidneys, the manifestations of the disease in the oral cavity have not yet been reported. The present paper reports unique oral lesions in a 38-yr-old woman, diagnosed as leukocytoclastic vasculitis, without any accompanying skin or systemic lesions.

Decreased expression of decay-accelerating factor on endothelial cells of immune complex-mediated vasculitic skin lesions

Endothelial cells may be damaged directly by the membrane attack complex of complement in immune complex vasculitis of the skin. However, for endothelial cell membrane injury to occur, normal regulatory mechanisms must fail. One of the main complement regulatory proteins of endothelial cells is decay-accelerating factor, a surface protein which interferes with either the classical or alternative pathway C3 and C5 convertases. We have investigated the expression of decay-accelerating factor in 4 patients with histologically proven cutaneous immune complex vasculitis, using an immuno-electronmicroscopic technique. We demonstrated that endothelial cells of upper dermal vessels in vasculitic lesions were almost completely devoid of decay-accelerating factor. By contrast, the expression of this protein on endothelial cells in uninvolved skin of the patients was the same as in skin of healthy volunteers. As yet, the mechanism responsible for depletion of decay-accelerating factor is not clear. Absence of decay-accelerating factor may follow enzymatic release from the phosphatidylinositol anchor, proteolytic stripping from the cell membrane or a down-regulation of decay-accelerating factor synthesis. Regardless of mechanism, endothelial cell injury or death could serve a phlogistic function to facilitate complement-mediated destruction of endothelial cells for removal and repair.

The sweat gland in cutaneous vasculitis

Cutaneous vasculitis commonly presents as palpable purpura, and the late stages may become nodular, bullous, infarcted and ulcerated. Involvement of sweat glands in vasculitic lesions has not been previously described. In a detailed study of 48 cases of non-infarcted cutaneous vasculitis, 18 (36%) revealed morphologically abnormal sweat glands. Basal cell degeneration, necrosis, regeneration and basal cell hyperplasia were found in the excretory ducts. Necrosis of the secretory gland was seen either as apoptosis involving the clear cells or as a whole gland necrosis involving both cell types. This unusual feature has only been described in association with coma, commonly due to barbiturate and carbon monoxide poisoning. Its presence in non-infarcted vasculitis adds support to the hypoxia/ischaemia hypothesis. The functional impact of such lesions in widespread cutaneous vasculitides requires further study.

Koebnerization as a cutaneous manifestation of immune complex-mediated vasculitis

Two unusual examples of the cutaneous manifestations of vasculitis are presented. In both cases lesions occurred on previously traumatized skin and on normal skin of the dependent areas. Lesional skin biopsy specimens obtained from the koebnerized sites and from the other dependent sites revealed evidence of vascular injury in both patients. A diagnosis of leukocytoclastic vasculitis was made in one patient and pityriasis lichenoides et varioliformis acuta in the other. Direct immunofluorescence microscopy of lesional skin specimens from both patients demonstrated dermal vascular immune deposits. Raji cell assay detected a significant elevation of circulating immune complexes in the serum of both patients. Neither koebnerizing leukocytoclastic vasculitis nor koebnerizing pityriasis lichenoides et varioliformis acuta has been reported previously.

Cutaneous immunofluorescence

Immunofluorescence, especially direct immunofluorescence of skin, has been widely used for diagnosis of connective tissue diseases. It is principally of value for LE and may be used also as a prognostic test for SLE. It is of relatively little value for diagnosis of other connective tissue diseases and appears not to predict the outcome of undifferentiated connective tissue disease. Cutaneous immunofluorescence is widely available and has an established place in the field of dermatopathology. As with other microscopic interpretations, substantial experience, along with an understanding of basic immunopathologic principles, is necessary for reliable results. Antibodies to certain ultrastructural components of the basement membrane zone are now available. These are being evaluated for further diagnostic applications to LE and other diseases that involve the epidermal basement membrane zone.

Complement-mediated endothelial cell damage in immune complex vasculitis of the skin: ultrastructural localization of the membrane attack complex

Activation of the complement system is an important element in our concept of the pathomechanism of immune complex (IC) vasculitis. Both deposition of IC and attraction of polymorphonuclear leukocytes (PMN) are effected by products of complement activation. Actual tissue damage, however, is believed to be caused by PMN penetrating the vessel wall. Our former finding that deposits of membrane attack complex of complement (MAC) are found predominantly in skin lesions of patients with IC vasculitis and not in perilesional skin, has raised the question whether the complement system itself (by way of the MAC) contributes to tissue damage. Our present study shows the ultrastructural localization of MAC in lesional and clinically uninvolved skin in two patients with a cutaneous IC vasculitis. Lesional skin deposits of MAC were found on endothelial cells (EC) of upper dermal vessels and on infiltrating PMN. Uninvolved skin deposits of MAC were found on some EC, but clearly to a lesser extent than on EC of the lesional skin. In the skin of two healthy controls MAC was only found sporadically on EC. Deposits of MAC on EC in the lesional skin were often associated with a typical form of local cell swelling. This local form of endothelial cell swelling was incidentally seen in vessels of clinically uninvolved skin, but not in the skin of the two controls. The association of the endothelial cell swelling with deposits of MAC suggests that the complement system can have a direct damaging effect on EC in IC vasculitis by the assembly of MAC on the endothelial cell membrane.

Neutrophilic vascular reactions

Dermatologic diseases are classified most commonly by morphology, by pathogenesis, or by etiology. Nontraditional classifications may be useful in terms of providing a reassessment of traditional views about disease interrelationships. This review of dermatoses characterized by neutrophilic infiltrates and dermal vessel changes reveals evidence suggesting that these dermatoses result from immune complex-mediated, neutrophil-induced dermal vessel damage. Therapeutic approaches to these heretofore unlinked dermatoses are remarkably similar.

Evidence of immune deposits and of basement membrane alterations in dermal vessels of normal skin of patients with essential mixed cryoglobulinemia

To gain insight into the pathogenic mechanisms of immune complex-mediated vasculitis, clinically normal skin specimens from the forearms of 12 patients with essential mixed cryoglobulinemia were investigated by light microscopy, immunofluorescence microscopy, and electron microscopy. Basement membrane alterations were documented in 9 patients. Eleven patients had deposits in vessel walls, but only in 1 was there evidence of inflammation. The same immunoglobulins of the cryoproteins could be demonstrated in the tissue deposits by immunofluorescence analysis and by immunoelectron microscopy. These findings suggest that, in essential mixed cryoglobulinemia, immune reactants in dermal vessels of normal skin are more common than is evidenced by clinical examination. Moreover, it seems that cryoglobulins, as such, are not sufficient to trigger an inflammatory process: Additional local or plasma factors are required. Deposits were absent in 7 patients with cryoglobulinemia that was associated with a primary disorder. This could be ascribed to the lower cryocrit levels documented in this group of patients, or to the shorter duration of their disease.

Sulfone therapy in the treatment of leukocytoclastic vasculitis. Report of three cases

Dapsone therapy for leukocytoclastic (necrotizing) vasculitis has been little used, except for the variant forms of erythema elevatum diutinum and urticarial vasculitis. We report three patients with the common (palpable purpura) form of the disease, limited to the skin, and successfully treated with moderate doses of dapsone (100-150 mg daily). Although the natural course of leukocytoclastic vasculitis is highly unpredictable, the prompt disappearance of new lesion formation after initiation of treatment and the rapid recurrence of lesions after therapy is discontinued (both often within 4 to 8 days after the critical dose level is reached) reflect drug efficacy. We believe that dapsone deserves wider evaluation as a therapeutic agent for chronic or recurrent cases of the common form of leukocytoclastic vasculitis.

Killing of human dermal capillary endothelial cells by antibody-dependent cellular cytotoxicity

Damage to the microvasculature occurs commonly in autoimmune diseases affecting the skin. There has been little investigation of immune mechanisms other than immune complex deposition as a major cause of microvascular damage. We have investigated the potential of antibody-dependent cellular cytotoxicity (ADCC) to cause vascular destruction in an in vitro model consisting of human dermal microvascular endothelial cells to which were added antibody and leukocytes. Severe damage was induced by antibody and lymphocytes. Monocytes or neutrophils were not able to mediate cytotoxicity although activated neutrophils caused endothelial detachment. The cytotoxic cells were OKT3-, Leu 11+ and were identified as K cells. ADCC was not inhibited by human serum or aggregated IgG. These results imply that ADCC may have a role in causing the vascular destruction observed in some human autoimmune skin diseases.

A simple and improved method for direct and indirect immunofluorescent staining

Several technics for immunofluorescent staining have been described in the literature and are presently used by laboratories performing direct and indirect tissue immunofluorescence. The purpose of this communication is to describe a simple immunofluorescent technic that uses a five-slide polypropylene slide mailer containing the diluted conjugated antisera. This technic eliminates the need for an incubation chamber, decreases background staining, and uses less antiserum.

Activation of the alternative pathway of complement by skin immune deposits

Skin immune deposits at the basement membrane zone have been demonstrated by functional assays to activate complement. This important biologic function has not yet been explored for immune deposits present in other locations mainly because many cytoplasmic structures in the skin have the capacity to activate the complement cascade by the classical pathway. In this study the capacity of immune deposits to activate directly the alternative pathway was examined using a functional guinea pig C3 binding test. This test was devised so as to avoid complement activation by normal cutaneous structures, thus it did not examine the capacity of immune reactants to activate the classical pathway. The main findings were that alternative pathway activation could be demonstrated only when human C3 deposits were seen by direct immunofluorescence, but not all C3 deposits were found to activate the alternative pathway; such activation was restricted to vascular deposits; the phlogistic potential of the immune deposits correlated with serologic evidence of ongoing immune reactions, i.e., hypocomplementemia and circulating immune complexes. It is suggested that this test provides data on one aspect of the phlogistic potential of skin immune deposits not detectable by direct immunofluorescence.

Cutaneous manifestations of serum sickness in patients receiving antithymocyte globulin

We have prospectively evaluated the cutaneous manifestations of serum sickness in thirty-five patients treated with horse antithymocyte globulin for bone marrow failure. Twenty-one patients (21/35) were treated with antithymocyte globulin (15 mg/kg/day) for 10 days, and fourteen of thirty-five patients were treated with antithymocyte globulin (15 mg/kg/day) for 14 days and then every other day for an additional 14 days. Clinical evidence of serum sickness developed in thirty patients and included fever and malaise (100%), cutaneous eruptions (93%), arthralgias and myalgias (67%), gastrointestinal complaints (67%), and lymphadenopathy (13%). Cutaneous findings consisted of morbilliform eruptions (n = 19), urticaria (n = 1), or a combination of these two reaction patterns (n = 8). Cutaneous manifestations of serum sickness began on day 7 +/- 1 and lasted for 12 +/- 2 days for the group as a whole. Biopsies of lesional skin revealed mild perivascular lymphohistiocytic infiltrates by light microscopy in these leukopenic patients. Direct immunofluorescence microscopy of lesional skin from patients with serum sickness demonstrated immunoreactants in seven of nine subjects (78%). Immunoreactants were confined to the walls of dermal blood vessels and consisted of IgM (7/9), C3 (6/9), IgE (5/9), and IgA (4/9). IgG (horse or human) was not identified in any of these specimens. Twenty-one patients (21/28) also developed an erythematous eruption on the sides of the fingers, toes, palms, and soles 12 to 48 hours prior to their morbilliform eruption. This study describes the cutaneous manifestations of human serum sickness occurring during therapy with horse antithymocyte globulin, documents a cutaneous sign of serum sickness, and suggests that the cutaneous eruptions associated with human serum sickness are immunologically mediated.

Pathogenesis of cutaneous lupus erythematosus

Antibody-dependent mechanisms of tissue damage are the principle mechanism of disease in systemic and cutaneous lupus erythematosus. Antibody-dependent mechanisms of keratinocyte damage appear to be a primary pathogenetic factor in all forms of papulosquamous cutaneous lupus. Photosensitive papulosquamous lupus syndromes, such as subacute cutaneous LE, neonatal LE, "ANA-negative" LE, and complement-deficient LE are all strongly associated with antibodies to the ribonucleoprotein SSA. Evidence is accumulating that antibodies to SSA (and perhaps to SSB) induce antibody-dependent cell-mediated cytotoxicity (ADCC) of basal keratinocytes in all of these lupus syndromes. Evidence is also growing that autoantibodies in cutaneous LE syndromes are directly involved in disease pathogenesis, and are not simply markers of disease subsets. The relationship of the photosensitive anti-SSA-associated LE syndromes to more classical discoid LE or to acute papulosquamous LE in SLE patients remains to be studied. In both discoid LE and acute LE, basal keratinocyte damage can be seen, just as in the anti-SSA-associated photosensitive LE syndromes, but other antigen-antibody systems may be involved in initiating keratinocyte damage, or other cytotoxic mechanisms may produce keratinocyte damage characteristic of these syndromes.

Human hypersensitivity angiitis, an immune complex disease

Human hypersensitivity angiitis is an immune complex disease in which patients present with palpable purpuric lesions of the skin and may often have multiple organ involvement. The antigen may be derived from an infectious organism such as the hepatitis virus, streptococcus, or a drug, and complexes with antibody. Under circumstances of vascular turbulence or vessel wall dilatation this complex may become fixed, activating the complement sequence with elaboration of chemotactic factors for neutrophils. These cells release lysosomal enzymes resulting in vessel wall destruction. Red blood cells leak into the tissue producing purpura and the inflammatory infiltrate accounts for the palpability. Although many patients have skin lesions only, others may have involvement of joints, gastrointestinal tract, kidneys, and even the lungs. The central question in the pathogenesis of this disease is why the immune complex is so selective in its site of deposition. Part of the reason must be related to the lattice formation of a particular complex, while other reasons are related to host factors of altered vascular permeability, integrity of clearance mechanisms or even a genetically determined defect of the phagocytic system.

Drug eruptions presenting at sites of prior radiation damage (sunlight and electron beam)

Two patients are described in whom sunburn and electron beam radiodermatitis, respectively, were critical determinants in localizing the initial presentation of drug eruptions. In the first instance, a severe sunburn of the back and thighs was followed 7 months later by the appearance of a toxic epidermal necrolysis drug reaction to trimethoprim-sulfamethoxazole in the exact sites of the previous bullous sunburn reaction. In the second patient, a radiodermatitis of the left upper arm due to electron beam therapy for metastatic breast cancer was followed 7 weeks later by a codeine drug reaction confined to the area of the radiodermatitis. In both instances, oral rechallenge with the offending drug reproduced the eruption.

Lymphocytic vasculitis: is it a specific clinicopathologic entity?

Seventy-one biopsy specimens taken at the Mayo Clinic from June 1977 through May 1981 demonstrated lymphocytic vasculitis. All specimens met the criteria for lymphocytic vasculitis, defined as (1) a predominantly lymphocytic infiltrate that involves and surrounds blood vessel walls, (2) fibrinoid necrosis of blood vessel walls, and (3) endothelial cell hyperplasia. Other histologic findings such as thrombosis, extravasation of erythrocytes, ulceration, epidermal infarction, and evidence of nuclear dust were seen only occasionally. Hypocomplementemia and other serologic abnormalities were very rare, even when lymphocytic vasculitis was extensive. The clinical diagnoses varied, with drug reaction (12 patients) and chronic urticaria (10 patients) being most frequent. In 32 cases, no specific diagnosis could be made at the time of dermatologic dismissal. In the remaining 39 cases, the diagnoses were varied and no definite clinical categories can be applied to them. We also observed typical lymphocytic vasculitis in some cases of other clinical entities, such as nodular scabies, erythema multiforme, and urticarial vasculitis, and so forth. We conclude that lymphocytic vasculitis is probably not a specific clinicopathologic entity but is more likely a reactive process, secondary to severe lymphocytic inflammation in the skin.

Electron-dense deposits in the renal arterioles of two patients with hypersensitivity vasculitis

Immune complex deposition in the vessel wall is presumed to be the major pathogenetic mechanism leading to hypersensitivity vasculitis. Despite this, histologic evidence of vascular immune complex deposition such as that provided by electron-dense deposits has been reported only rarely in dermal vessels and never in visceral organs. The cases of two patients with hypersensitivity vasculitis affecting primarily the skin and the kidney are reported. Clinical renal involvement was manifested by proteinuria, hematuria, and a moderate increase in serum creatinine in one case. Renal biopsy showed minimal glomerular changes in one patient and focal necrotizing glomerulitis in the other. The arterioles appeared normal on light microscopic examination. However, obvious electron-dense deposits in the arteriolar wall could be demonstrated electron microscopically in both cases. This observation lends strong support to the theory of immune-complex-mediated vascular damage as the main pathophysiologic mechanism in vasculitis with visceral involvement.

Neurological complications of vasculitis

The vasculitides are a group of disorders that include the polyarteritis nodosa group of systemic necrotizing vasculitides, hypersensitivity vasculitis, Wegener's granulomatosis, lymphomatoid granulomatosis, giant cell arteritis, Behçet's disease, and isolated angiitis of the central nervous system. Classification is based on clinical, angiographic, and histological features. The frequency and distribution of neurological involvement vary with the underlying disorder and may provide the initial symptoms. Polyarteritis nodosa and Wegener's granulomatosis may affect both the central and peripheral nervous systems, whereas isolated angiitis of the central nervous system and Behçet's disease affect the central nervous system alone. Neurological dysfunction occurs in 80% of patients with polyarteritis nodosa and fewer than 10% of patients with hypersensitivity vasculitis. The mechanism of neurological dysfunction in the vasculitides is tissue ischemia. The clinical effects of ischemia vary, and symptoms may be transient or prolonged. Mononeuritis multiplex, polyneuropathy, and stroke are frequent complications, but encephalopathies, cranial neuropathies, and brachial plexopathies are seen as well. The occurrence of symptoms late in the course of a disease suggests ischemia resulting from healed, scarred vessels as well as from those that are acutely inflamed; this is the case in Takayasu's arteritis and possibly also in polyarteritis nodosa. Treatment is based on identifying and removing the sensitizing agent when possible. Wegener's granulomatosis requires therapy with cyclophosphamide; temporal arteritis, with corticosteroids. In other vasculitides a balance must be reached between the progression of the disease and the side effects of immunosuppression.

Complement deposition in the skin of patients with herpes-associated erythema multiforme

Granular staining for C3 by direct immunofluorescence is a frequent finding along the dermoepidermal junction and in papillary blood vessels in the early skin lesions of erythema multiforme. In order to evaluate whether the complement cascade is activated by the classical or alternative pathway, ten biopsies from patients with herpes-associated erythema multiforme, which were positive for granular C3 along the dermoepidermal junction, were stained by an immunofluorescence technic for other complement components. Staining for the components of classical pathway, C1q and C4, were found in none of the ten biopsies. However, in nine of ten biopsies, granular staining for properdin was present along the dermoepidermal junction. These findings suggest complement activation by the alternative complement pathway in herpes-associated erythema multiforme.

Circulating immune complexes in Henoch-Schonlein purpura

Henoch-Schonlein purpura (HSP) is a symptom complex which may involve the skin, joints, gastrointestinal tract, and kidney. Skin involvement occurs in more than 50% of the patients and may appear as erythematous purpuric macules or papules. The skin lesions show histologic features of leukocytoclastic vasculitis. Deposits of immunoglobulin and complement may be present in the involved vessel walls. A case of HSP is described where high levels of circulating immune complexes were found. This further suggests the possible involvement of immune complexes in the pathogenesis of HSP.

Dermatologic conditions reported in patients with rheumatoid arthritis

Dermatologists, while becoming increasingly involved in the diagnosis and management of patients with connective tissue diseases, have left rheumatoid arthritis relatively unexplored. An increased awareness of possible pathomechanisms of rheumatoid arthritis may allow for generalizations that lead to increased understanding of other connective tissue disorders. The types of cutaneous disorders that occur in association with rheumatoid arthritis include: vasoreactive dermatoses (e.g., various forms of vasculitis), which may occur secondary to the circulating immune complexes present in rheumatoid arthritis; autoimmune bullous disorders, which may occur in the setting of a suppressor T cell defect in rheumatoid arthritis; and various miscellaneous cutaneous associations. Hopefully, this review will lead to an increased understanding of both rheumatoid arthritis and the wide array of cutaneous associations of rheumatoid arthritis.