Alteration of human epidermal transglutaminase during its activation

The effects of enhancement of enzymatic activity by heating at 56 degrees C or by limited treatment with dimethylsulfoxide, trypsin and cathepsin D on two forms (Mr = 50 kDa and 72 kDa) of human epidermal transglutaminase were studied by immunoblots using rabbit antihuman epidermal transglutaminase. Both 50 kDa and 72 kDa transglutaminase bands were detected without any alteration in the mobility of the transglutaminase bands during activation induced by heating at 56 degrees C or by pretreatment with dimethylsulfoxide. With a preincubation period longer than 60 min, the trypsin pretreated sample showed progressive disappearance of the 72 kDa transglutaminase band in conjunction with the loss of transglutaminase activity. On the other hand, samples preincubated with cathepsin D showed a complete disappearance of the 50 kDa band after 180 min. These studies suggest the different forms of human epidermal transglutaminase may regulate enzyme activity each other during normal epidermal differentiation.     

Similarity between mycobacterial and human epidermal antigens

Eight out of 17 mouse anti-Mycobacterium leprae monoclonal antibodies (MAb) were previously observed to react with human nerve and skin antigenic determinants in cryostat sections, using an indirect immunoperoxidase technique. These observations suggested that antigenic mimicry may be involved in the development of the clinical manifestations of leprosy. In the present study we have extended our earlier findings by investigating sera from leprosy patients and MAb using Western blot technique. It was observed that 30 sera and their corresponding F(ab')2 fragments from isolated IgG fractions of both tuberculoid and lepromatous patients reacted with 40-50 epidermal proteins of molecular weights (MW) ranging from 10 to 130 kDa. Sera from 14 controls, however, showed similar reactivity patterns. Absorption of nine patient and control sera with M. tuberculosis, M. marinum and M. kansasii resulted in the removal of several components of different MW in nine, four and three cases, respectively. No consistent differences between sera from leprosy patients and controls were observed. Four out of eight MAb against M. leprae which reacted with determinants in human epidermis and/or dermis in skin cryostat sections reacted with epidermal proteins of MW higher than 39 kDa in Western blot. Four MAb which showed reactivity in cryostat sections did not react in Western blot. Another four MAb did react with human epidermal proteins in Western blot but did not react in cryostat sections, indicating that the MAb were reacting with different epitopes in the two systems. Five MAb did not react with human epidermal proteins either in cryostat sections or in Western blot.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hsp72 antigen expression in the proliferative compartment of involved psoriatic epidermis

Oxidative damage to growth regulatory proteins has been implicated in the aetiology of psoriasis. However, the transient synthesis of heat shock proteins has been shown to protect cells against the adverse effects of oxidative and other forms of physiological stress. This study has used an hsp72 monoclonal antibody to measure inducible 72 kDa heat shock protein expression in heat stressed normal human skin and established plaque psoriasis. Hsp72 was detected in the basal and suprabasal layer cells of heat-stressed normal skin, and in 12 involved psoriasis lesions. Hsp72 expression was not detected in unstressed normal skin or in 12 cases of uninvolved psoriasis. Immunoprecipitation and Western blotting of cell lysates from heat stressed normal skin and involved psoriasis lesions confirmed the presence of a 72 kDa polypeptide with hsp72 immunoreactivity. The MIB-1 monoclonal antibody was used to determine the proliferative fraction of normal and involved psoriastic epidermis. The Ki67 antigen was localised to the nuclei of basal and suprabasal layer cells of normal and involved psoriatic epidermis. Involved psoriatic epidermis contained a higher number of proliferating keratinocytes when compared with normal skin. The study has also demonstrated a strong correlation between hsp72 expression and keratinocyte proliferation in involved psoriatic epidermis (r=0.864, p<0.001). We believe that the 72 kDa inducible heat shock protein performs a protective function in the proliferative compartment of normal and involved psoriatic skin.     

Isolation and characterization of a lower molecular weight protein doublet of horny cell outer leaflet: a possible novel epidermal differentiation marker

The water-soluble fraction of stratum corneum contains numerous unidentifiable proteins and polypeptides when examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Intensely stained polypeptide bands of low molecular weights (LMW) [8 and 10 kDa] are also present, and the abundance and invariable presence of this LMW protein doublet in the soluble proteins of stratum corneum prompted us to isolate and characterize them. Extracts of stratum corneum, using 8 M urea, 0.05 M Tris, pH 9.0, 0.025 M 2-mercaptoethanol, were dialysed against water. Water-insoluble proteins were removed by repeated dialysis and centrifugation. From the remaining soluble proteins, a LMW protein doublet was isolated by Sephadex G50 column chromatography and reversed-phase high-performance liquid chromatography (HPLC). The amino acid compositions of the 8 and 10 kDa proteins were similar to, but different from, those of known structural proteins in the stratum corneum. Rabbit antibody was raised against the 10-kDa protein band and cross-reacted with the 8-kDa protein band by Western immunoblot technique. The antibody recognized only this protein doublet amongst the proteins extracted from cultured keratinocytes. The 8- and 10-kDa proteins therefore appear to be closely related to, but different from, known structural proteins or degradation products. Immunofluorescence and immunoelectron microscopy demonstrated that this protein doublet was located in the cytoplasm of the cells of the malpighian layer, and in the outer layer of the marginal band of the horny layer. Its distribution was shown to be limited to stratified squamous epithelia by organ specificity studies. These results suggest that this protein doublet appears to be a novel soluble protein and a new epidermal differentiation marker of stratified epithelium.     

Positive correlation between serum immunoreactivity to Demodex‐associated Bacillus proteins and erythematotelangiectatic rosacea

Background Rosacea is a chronic inflammatory condition that affects the skin of the face and the eyes. Erythematotelangiectatic rosacea is characterized by flushing, oedema and telangiectasia. Patients with rosacea demonstrate elevated densities of Demodex mites in their skin compared with controls. A bacterium (Bacillus oleronius) isolated from Demodex mites from a patient with papulopustular rosacea has been demonstrated to produce antigenic proteins that may play a role in papulopustular and ocular rosacea. Objectives To establish whether there was a correlation between the reactivity of sera from patients with erythematotelangiectatic rosacea to Bacillus antigens, and to characterize the proteins to which these patients showed reactivity. Methods Serum samples from patients with erythematotelangiectatic rosacea and controls were examined for reactivity to Bacillus proteins by Western blot analysis. Proteins to which the sera reacted were excised from gels, trypsin digested, and putative identities were assigned following liquid chromatography‐mass spectrometry (LC‐MS) analysis. Results Eighty per cent (21/26) of patients with erythematotelangiectatic rosacea showed serum reactivity to the 62‐ and 83‐kDa proteins of B. oleronius, compared with 40% (9/22) of controls (P = 0·004). The 62‐kDa protein was characterized by LC‐MS and showed homology to groEL chaperonin, which provokes a strong immune response in mammals. The 83‐kDa protein showed homology to aconitate hydratase, of which expression is increased in bacteria under oxidative stress, and which is highly immunogenic. Conclusions The majority of patients with erythematotelangiectatic rosacea show serum reactivity to two proteins from B. oleronius, suggesting that this bacterium may play a role in the induction of this condition. The two proteins to which patient sera reacted were found to be similar to a heat shock protein and an enzyme involved in regulating the stress response of the bacterium.     

Antigenic components of Malassezia species for immunoglobulin E antibodies in sera of patients with atopic dermatitis

Antigenic components of Malassezia furfur, M. globosa, M. restricta, M. slooffiae, and M. sympodialis were studied for immunoglobulin E antibodies in sera of patients with atopic dermatitis (AD). Antigenic components were extracted from Malassezia cells by treatment with beta-mercaptoethanol, referred to as 2-ME extract. CBB staining and lectin blots using Con A, LCA, PHA-E4, PNA or RCA120 showed that the 2-ME extracts contained several species-dependent components that differed quantitatively and qualitatively among the Malassezia species at the protein level. In the Western blot with the 2-ME extracts, of 54 sera of the patients with AD (54 patients), the patients' IgE antibodies most frequently recognized components showing molecular weights of 43-46 kDa for M. slooffiae, 12-22 kDa for M. sympodialis, 35-40 kDa for M. restricta, 45-50 kDa for M. globosa, and of 67-72 kDa for M. furfur, respectively. In the correlative study, in which the total band intensities generated for each extract in Western blot were compared among the Malassezia species, the intensity for M. globosa was well correlated with that for M. sympodialis (r=0.756). In the Western blot inhibition test, the 2-ME extract of M. globosa partially inhibited the reaction of the antigenic components of other Malassezia species with the patient's IgE antibodies. These results indicated that Malassezia species contained both species-specific and common antigenic components at the IgE antibody level.     

Properties and histochemical application of a novel antibody against trichohyalin granules

We obtained an antibody, anti-inner root sheath cells antibody (anti-IRSC Ab), that reacted with the inner root sheath (IRS) cells especially trichohyalin granules (THG). In order to compare the properties of anti-IRSC Ab and AE15, which is a specific monoclonal antibody against THG, histochemical and biochemical examinations were performed. In vivo localization with anti-IRSC Ab and AE15 indicated that both antibodies reacted with THG, but anti-IRSC Ab reacted with THG in the suprabulbar region of the Huxley layer, whereas AE15 reacted with THG in the suprabulbar region and upper bulbar portion of the Huxley layer, as shown by immunohistochemical and immunoelectron microscopic analyses. The results of immunoblot analysis showed that anti-IRSC Ab reacted with a protein spot at 45 kDa, pI 6.5, but AE15 reacted with high molecular weight proteins at pI 5.5. Furthermore, anti-IRSC Ab reacted with specimens of squamous cell carcinoma (SCC) but did not react with those of basal cell carcinoma (BCC). In contrast, AE15 reacted with neither SCC nor BCC. These findings suggest that anti-IRSC Ab and AE 15 recognized different component proteins in THG, and therefore indicated that THG, like as keratohyalin granules, might consist of several proteins. It is the novel finding that the anti-IRSC Ab positive substance in THG in the normal hair and SCC cells.     

Distinct types of IgG and IgA anti-intercellular autoantibodies from patients with pemphigus and vesiculopustular dermatosis

The pattern of binding of two different types of IgA class pemphigus-like antibodies was compared with that of the true IgG class pemphigus antibody. The IgG antibodies from pemphigus vulgaris (PV) and pemphigus foliaceus (PF) sera bound to the intercellular spaces in normal human epidermis, whereas only the PV antibody reacted with monolayers of keratinocytes derived from human foreskin. Both IgG and IgA antibodies from a patient with PF were found in the intercellular spaces of the epidermis and only the IgA antibody reacted with the cultured keratinocytes. The IgA antibody from a patient with a vesiculopustular eruption and whose serum contained IgA intercellular space antibody alone, bound to the upper epidermis but not to the monolayers of keratinocytes. These findings indicate that PV but not PF antigens can be expressed by monolayers of cultured human keratinocytes and that there are at least two distinct types of IgA intercellular antibodies.     

Epidermolysis bullosa acquisita antigen: relationship between the collagenase-sensitive and -insensitive domains

To clarify the relationship of the 290 and 145 kDa chains of the epidermolysis bullosa acquisita (EBA) antigen, we subjected urea extracts of skin basement membrane zone (BMZ) proteins and isolated 290 and 145 kDa chains of the EBA antigen cut out of sodium dodecyl sulfate polyacrylamide gels to treatment with clostridial collagenase. When the reaction products were electrophoresed, transblotted, and reacted with EBA patient sera or two monoclonal antibodies to the EBA antigen, the 290 kDa chain was degraded into the 145 kDa band that was resistant to cleavage with collagenase. The 145 kDa domain, isolated after collagenase treatment of the whole BMZ extract, was resistant to degradation by hyaluronidase, chondroitinase ABC, heparinase, and heparitinase but was readily degraded by V-8 protease. These data suggest that the EBA antigen consists of collagen and noncollagen domains of identical size (Mr 145,000), and that the 145 kDa noncollagen domain is generated via degradation of the native 290 kDa species by collagenase.     

Studies of the relationship of the 230-kD and 180-kD bullous pemphigoid antigens

In bullous pemphigoid (BP), autoantibodies from most patients recognize a high molecular weight 230-kD epidermal antigen (Ag) by immunoprecipitation. By Western immunoblotting, 50-70% of sera recognize the high molecular weight Ag, but 30-50% recognize a low molecular weight, 180-kD epidermal Ag. We examined the specificities of affinity-purified antibodies against these Ag. Antibodies specific for the 230- and 180-kD Ag were prepared by immunoaffinity against Ag immobilized on nitrocellulose and released by acid glycine. IgG eluted from the 230-kD Ag band retained its specific binding to the 230-kD Ag by immunoblotting, and bound to the epidermal basement membrane zone (BMZ) by indirect immunofluorescence (IF) and to hemidesmosomes by indirect immunoelectron microscopy (EM). IgG affinity purified by the 180-kD Ag band bound only the 180-kD Ag in immunoblotting, with no cross reaction to the 230-kD Ag, bound the epidermal BMZ by indirect IF, and also bound to hemidesmosomes in immuno-EM. IgG specific for the 230-kD Ag in immunoblotting immunoprecipitated only the 230-kD Ag, with no apparent precipitation of the 180-kD Ag. Surprisingly, IgG specific for the 180-kD Ag precipitated both the 180- and the 230-kD Ag in immunoprecipitation, and the 230-kD Ag band was much more intense than the 180-kD Ag band. This study shows that apparent cross-reactivity between these Ag by BP autoantibodies can only be detected in native conditions by immunoprecipitation, and cannot be demonstrated using denatured Ag in immunoblotting. The two proteins appear to be distinct Ag, closely associated in the epidermal hemidesmosome, but the exact relationship of these Ag to each other may not be clarified until complete structural data become available.     

Galectin‐7 and actin are components of amyloid deposit of localized cutaneous amyloidosis

The precursor protein of localized cutaneous amyloidosis (LCA) is believed to be cytokeratins on the basis of previous immunohistochemical studies. To identify the candidate amyloid protein biochemically, amyloid proteins were extracted with distilled water from lesional skin of LCA associated with Bowen's disease. The proteins were resolved on one‐ or two‐dimensional polyacrylamide gel electrophoresis followed by characterization with immunoblot analysis. The proteins with multiple molecular weights of 50–67 kDa and two proteins with 25 and 35 kDa were identified as keratins, serum amyloid P component and apolipoprotein E, respectively. The unknown 14‐kDa (pI = 7.0) and 42‐kDa (pI = 5.4) proteins reacted with the antibody against galectin‐7 and actin, respectively. The protein with the molecular weight of 14 kDa was identified as galectin‐7 by MALDI‐TOF mass spectrometer. Their electrophoretic mobilities were identical with normal counterparts extracted from cultured normal human keratinocytes. Galectin‐7 and actin were detected by immunoblot assay in the water‐soluble fractions prepared from the lesional skins of two patients with primary LCA. Immunohistochemical studies of tumor‐associated (n = 9) and primary (n = 10) LCA revealed various degrees of positive immunoreactivities with the antibodies for galectin‐7 and F‐actin. Galectin‐7 and actin, which contain considerable amount of β‐sheet structure, may be candidate amyloidogenic proteins of primary and secondary LCA.     

Antikeratin 14 monoclonal antibody staining in psoriasis and seborrhoeic keratosis: immunofluorescence and two colour FACS studies

Summary A monoclonal antibody (ES3A) was raised against a mouse graft-versus-host reaction (GVHR) model. This antibody was against basal cell cytoplasm and reacted with an acidic (pI 6.2) 50 kDa keratin of human epidermis. However, ES3A reacted with several lower layers of epidermal cells in psoriasis and seborrhoeic keratosis. Acanthotic seborrhoeic keratosis showed varying patterns even in a single lesion. If combined with FACS analysis, ES3A-positive cells could be quantified. Normal skin showed 28%, while psoriasis and seborrhoeic keratosis showed 44% and 51%, respectively. ES3A-positive compartments of the acanthotic type of seborrhoeic keratosis were larger than those of the hyperkeratotic type. ES3A may be suitable for quantification of germinative or proliferative cells.     

淋病奈瑟菌膜蛋白抗原表位的研究

目的利用人工合成多肽制备针对淋球菌外膜蛋白PIB抗原表位的特异性多克隆抗体,以期用于淋球菌的检测,为进一步建立新型淋病快速诊断方法提供研究基础。方法根据PIB抗原表位的氨基酸序列合成一段多肽(LD1),并将其与钥孔血蓝蛋白(KLH)偶联构成完全抗原LD1-KLH,免疫动物,收集抗血清,用ELISA和Western blot检测其特异性。结果ELISA检测表明,LD1-KLH具有免疫原性,免疫动物能刺激机体产生较强的体液免疫反应,兔血清抗体和豚鼠血清抗体效价最高分别达到1:3200和1:25600;抗血清能与淋球菌临床株特异性结合,与葡萄球菌、链球菌、大肠杆菌和真菌等其他微生物之间没有交叉反应;Westernblot结果显示,抗血清能识别淋球菌裂解物,产生特异性条带,相对分子质量(Mr)为37300。结论人工合成多肽具有免疫原性,能诱导机体产生识别淋球菌抗原表位的特异性抗体。     

Serum antibodies to Trichomonas vaginalis in invasive cervical cancer patients.

OBJECTIVE--To evaluate, by seroepidemiology, the possible role of the sexually-transmitted flagellate, Trichomonas vaginalis, in invasive cervical cancer. SUBJECTS AND METHOD--Sera from 121 invasive cervical cancer patients and 242 random age-matched female controls. Antibodies to T. vaginalis were detected by the western blot technique. RESULTS--Antibodies to T. vaginalis were detected in the sera of 41.3% (50/121) of invasive cervical cancer patients compared with only 5.0% (12/242) of female controls. All the reactive sera reacted strongly with the immunogenic surface membrane proteins of T. vaginalis of molecular weights of about 92 and 115 kDa, with variable reactivity to other immunogenic proteins of T. vaginalis. CONCLUSION--The significantly increased relative risk, RR = 3.42 (95% CI = 1.73-6.78), is comparable to the RRs derived in seroepidemiological studies of human papillomavirus, suggesting that T. vaginalis may be even more closely associated with invasive cervical cancer than previously realized.     

A vesicular variant of bullous pemphigoid with autoantibodies against unidentified 205- and 150-kDa proteins at the basement membrane zone

Summary We describe a 75-year-old man who developed a vesicular variant of bullous pemphigoid with a distinctive result of immunoblot analysis. Characteristic symptoms consisted of vesiculopapular eruptions with erythematous patches on the arms and legs, many of which fused to form irregularly outlined areas of erythema varying in size. Direct immunofluorescence revealed a linear deposition of IgG at the basement membrane zone of the skin, and indirect immunofluorescence detected circulating IgG autoantibodies at a titre of 1: 160. which reacted with the antigens located on the epidermal side of skin split with 1 mol/L, NaCI. Immunoblot analysis using epidermal extracts demonstrated the presence of IgG antibodies directed to 150, 205, 240 and 280 kDa proteins as well as to the 180kDa bullous pemphigoid antigen (BPAG2). All antibodies eluted from nitrocellulose membrane imprints of individual bands with molecular weights of 150, 180 and 205 kDa were found by indirect immunofluorescence to react with the basement membrane zone, whereas those elutcd from the bands with molecular weights of 240 and 280 kDa did not. These findings suggest that antibodies directed not only to the 180kDa BPAG2, but also to 150 and 205 kDa proteins, are involved in the pathogenesis of bulla formation in this patient.     

Lichen planus pemphigoides: its relationship to bullous pemphigoid

Clinical and immunopathological studies of three patients with lichen planus pemphigoides (LPP) were carried out to investigate the relationship between LPP and bullous pemphigoid (BP) and to determine whether the antigen in LPP is the classical BP antigen. LPP is usually considered to be the coexistence of lichen planus with BP. The bullae in LPP were subepidermal and indistinguishable from BP. Indirect immunofluorescence demonstrated antibody binding to the epidermal surface of 1 M NaCl-split skin and mucosae, as in BP. The tissue distribution of the LPP antigen mirrored the distribution of BP in stratified squamous epithelia but was absent from transitional epithelia (pig bladder). Immunoelectron microscopy, both direct (two cases) and indirect (one case), showed binding to the lamina lucida as with BP antigen. Western blotting of epidermal extracts using the patients' sera showed that instead of reacting with the classical bullous pemphigoid antigen (220 kDa in our series), the antisera reacted with a unique band of 200 kDa in addition to the band of 180 kDa found as a minor antigen in bullous pemphigoid, but more commonly in pemphigoid gestationis. The relationship between these antigens awaits molecular characterization. These findings suggest that the target antigen in LPP may be unique.     

Coexistence of beta2 microglobulin and lambda light chain in amyloid fibrils of dialysis-unrelated plasma cell dyscrasia-associated systemic amyloidosis

BACKGROUND: Systemic amyloidosis occurs as a result of amyloid deposition in various tissues. The amyloid fibrils in systemic amyloidosis have been reported to originate from immunoglobulin light chains. OBJECTIVE: We studied the composition of amyloid fibrils from two patients with plasma cell-associated systemic amyloidosis (PASA). METHODS: A double immunofluorescence study of the lesional skin of PASA was undertaken. Amyloid proteins were extracted with distilled water from one case of PASA. RESULTS: The double immunofluorescence study showed that anti-lambda light chain and anti-beta2 microglobulin antibodies mostly reacted with the same area of amyloid deposit. Amyloid deposits from two patients with PASA who had never undergone haemodialysis showed a positive reaction with the antibodies for beta2 microglobulin as well as immunoglobulin lambda light chain. By the use of immunoblot assay of amyloid fibril proteins, polypeptides immunoreactive with antigamma light chain antibody (29 kDa) and with anti-beta2 microglobulin antibody (12 kDa) were detected. CONCLUSIONS: These results indicate that beta2 microglobulin is a component of amyloid fibrils in PASA.     

Immunoblot and immunoelectronmicroscopic analysis of endemic Tunisian pemphigus

Tunisian pemphigus is a newly described form of endemic pemphigus whose clinical, histological and epidemiological characteristics have recently been detailed. The objective of this study was to analyse the binding properties of autoantibodies present in sera from patients with endemic Tunisian pemphigus using immunoblotting and indirect immunoelectron microscopy (IEM). Thirty patients with pemphigus foliaceus (PF) and six with pemphigus vulgaris (PV) seen in the dermatology department of Tunis Hospital between 1992 and 1994 were selected for this study. Seven of 30 (23%) and six of 12 (50%) PF sera tested bound to the 160 kDa band of desmoglein 1 when tested on bovine tongue and human epidermal extracts, respectively. Two of six and two of three PV sera tested bound to the 130 kDa desmoglein 3 in these two extracts. Immunoblot and indirect IEM showed that 24 of 30 (80%) PF sera contained IgG1, IgG3 or IgG4 antibodies that bound to a 185-kDa polypeptide localized on the desmosomal plaque. This immunological analysis showed that most endemic Tunisian pemphigus sera correspond to PF sera and are characterized by a high frequency of autoantibodies directed against a recently identified 185-kDa antigen of the desmosomal plaque.     

Paraneoplastic pemphigus without antidesmoglein 3 or antidesmoglein 1 autoantibodies

Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous blistering disease characterized by IgG autoantibodies that bind to various epithelia and immunoprecipitate a complex of 250, 230, 210, 190 and 170 kDa proteins. A recent study has suggested that PNP patients have antidesmoglein (Dsg) 3 autoantibody and that the antibody plays a pathogenic role in PNP. We report a 72-year-old woman with PNP associated with thymoma and adenocarcinoma of the lung. Diagnosis of PNP was made by the characteristic clinical, histological and immunopathological findings, as well as immunoprecipitation of characteristic 230, 210 and 190 kDa proteins. Using enzyme-linked immunosorbent assay with baculovirus-expressed recombinant proteins, the patient's serum was negative against both Dsg 3 and Dsg 1. This finding is unusual, and it suggests that the target antigen, which is involved in acantholysis, may be other than Dsg 3 in this case.     

Advanced glycation end product-modified beta2-microglobulin is a component of amyloid fibrils of primary localized cutaneous nodular amyloidosis

Primary localized cutaneous nodular amyloidosis is a rare form of cutaneous amyloidosis. Amyloid fibrils in primary localized cutaneous nodular amyloidosis have been reported to be originated from immunoglobulin light chains. Immunohistochemical studies on the lesional skins of four patients with primary localized cutaneous nodular amyloidosis demonstrated that amyloid deposits of all cases showed a positive reaction with the antibodies for beta2-microglobulin and advanced glycation end products as well as immunoglobulin light chain (kappa or lambda). No beta2-microglobulin and advanced glycation end product immunoreactivity was found in the amyloid deposits of other primary localized cutaneous amyloidosis (lichen amyloidosis and macular amyloidosis). Double immunofluorescence study of the lesional skin of primary localized cutaneous nodular amyloidosis showed that anti-kappa light chain, anti-beta2-microglobulin and anti-advanced glycation end product antibodies mostly reacted with the same area of amyloid deposit. Amyloid proteins were sequentially extracted with distilled water from one case of primary localized cutaneous nodular amyloidosis and recovered in the five water-soluble fractions (fractions I-V). Immunoblot assay of amyloid fibril proteins demonstrated that immunoreactive polypeptides with anti-kappa light chain antibody (29 kDa) and with anti-beta2-microglobulin antibody (12 kDa) were detected in fractions I-V, whereas immunoreactive polypeptide with anti-advanced glycation end product antibody (12 kDa) was detected exclusively in fractions III-V but not in fractions I and II. Two-dimensional polyacrylamide gel electrophoresis revealed that 12 kDa polypeptide in fractions I and II was electrophoretically identical with authentic beta2-microglobulin and that beta2-microglobulin in fractions III-V was advanced glycation end product-modified beta2-microglobulin with more acidic pI value. These results indicate that beta2-microglobulin is another major component of amyloid fibrils in primary localized cutaneous nodular amyloidosis and that beta2-microglobulin in primary localized cutaneous nodular amyloidosis is partly subjected to the modification of advanced glycation end product.