Detection of antibodies against the non-calcium-dependent epitopes of desmoglein 3 in pemphigus vulgaris and their pathogenic significance

BACKGROUND

Antidesmoglein (anti-Dsg) 3 serum antibody titres are usually correlated with the disease activity of pemphigus vulgaris (PV), but some patients retain high titres even in remission.

OBJECTIVES

The aim of our study was to determine whether anti-Dsg3 antibodies in PV sera recognized calcium (Ca(2+) )-dependent or non-Ca(2+) -dependent epitopes, and to evaluate their pathogenicity.

METHODS

Dsg3 baculoprotein-coated enzyme-linked immunosorbent assay (ELISA) plates were treated with 0.5 mmol L(-1) ethylenediaminetetraacetic acid (EDTA). The binding ability of anti-Dsg3 monoclonal antibodies (mAbs) was analysed. Eight of the 83 patients with PV who were screened had elevated Dsg3 ELISA index values > 00 in remission. The binding ability of these PV sera was analysed. We evaluated the pathogenicity of anti-Dsg3 serum antibodies against the non-Ca(2+) -dependent epitopes using a dissociation assay.

RESULTS

The reactivity of pathogenic anti-Dsg3 mAbs against the Ca(2+) -dependent epitopes diminished markedly in the EDTA-treated ELISA, whereas no such reduction was observed in mAbs against the non-Ca(2+) -dependent epitopes. The sera of all the patients contained antibodies against both Ca(2+) -dependent and non-Ca(2+) -dependent epitopes. In six out of the eight patients, the ratio of antibodies against Ca(2+) -dependent to non-Ca(2+) -dependent epitopes decreased in remission. EDTA-treated Dsg3 baculoproteins adsorbed anti-Dsg3 serum antibodies against the non-Ca(2+) -dependent epitopes, but the remnant PV antibodies retained the ability to induce acantholysis in the dissociation assay.

CONCLUSIONS

We have established an assay to measure indirectly the titres of anti-Dsg3 serum antibodies against the Ca(2+) -dependent epitopes, based on the differences between EDTA-untreated and EDTA-treated ELISA index values, as a routine laboratory test to reflect the pathogenic anti-Dsg3 serum antibody titres more accurately.

Involvement of granulysin-producing T cells in the development of superficial microbial folliculitis

BACKGROUND

Granulysin is a recently identified antimicrobial protein expressed on cytotoxic T cells, natural killer (NK) cells and NKT cells. It has been shown that granulysin contributes to the defence mechanisms against mycobacterial infection. Superficial microbial folliculitis is a common skin disease. In a previous report, we showed that, as a first line of defence, alpha-defensin, a human neutrophil peptide, and beta-defensin (human beta-defensin-2) were expressed in infiltrating neutrophils and in lesional epidermal keratinocytes, respectively, in superficial folliculitis. As we also observed many infiltrating lymphocytes in lesional dermis, we hypothesized that infiltrating lymphocytes may possess antimicrobial substances, such as granulysin, and play a role in the defence mechanism as a second line of defence.

OBJECTIVES

Seven specimens of superficial microbial folliculitis diagnosed clinically and histologically were examined by means of immunohistochemistry. To identify the phenotype of cells expressing granulysin, confocal laser microscopic examination was performed.

RESULTS

A dense lymphoid cell infiltrate was observed in pustules, in the perivascular regions. A large number of these lymphoid cells were positive for granulysin. Phenotypically, cells consisted of CD3+ T cells, CD8+ T cells and UCHL-1+ T cells. CD20+ cells and CD56+ cells were not observed. Microscopic examination with a confocal laser showed that the lymphocytes producing granulysin were CD3+ and CD4+ T cells but not CD8+ T cells.

CONCLUSIONS

We showed that many granulysin-bearing T cells infiltrated affected follicles and perilesional dermis in superficial microbial folliculitis. However, few granulysin-positive lymphoid cells were observed in sterile pustular lesions. Our observations indicated that adaptive immunity such as granulysin, a lymphocyte-produced antimicrobial protein, may play an important role in the cutaneous defence mechanism.

Detection of cryptdin in mouse skin

Defensins are widely distributed and broad-spectrum antimicrobial peptides with activities against bacteria, fungi, and enveloped viruses. Defensins have been isolated from granules of neutrophils from humans, rabbits, rats, and guinea pigs. They have also been found in lung macrophages as well as in Paneth cells of the human, rabbit, and mouse small intestine. The human beta-defensin-2 was recently isolated from human skin. In this study, we detected the expression of mRNA for the defensin cryptdin in BALB/c mouse skin by means of reverse transcriptase PCR amplification. Expression was also detected in dispase-separated epidermis and cultured keratinocytes, but expression was not detected in fibroblasts. The expression of cryptdin mRNA was found to begin on embryonic day 17.5. As determined with specific primers, the cDNA sequence cloned from the skin was found to be identical to that previously reported for cryptdin-5. cDNA derived from cultured keratinocytes demonstrated the sequences of the cryptdin-6 and cryptdin-1 isoforms. In situ hybridization analysis showed that the mRNA of cryptdin was expressed in the suprabasal keratinocytes of the skin in embryonic and neonatal days and then shifted to the hair bulbs in the skin of adult mice.

Hyperimmunoglobin E syndrome: a sign of TH1/TH2 imbalance?

We report on a patient with hyperimmunoglobulin E syndrome, who developed pruritic vesiculopapules from the age of six months and also had recurrent episodes of skin abscesses and oral thrush. Serum IgE was extremely elevated at 59,514 IU/ml and specific IgE antibody to Staphylococcus aureus was positive. Histological examination from a vesiculopapule on the face revealed that eosinophil-rich infiltration involved hair follicles, similar to eosinophilic pustular folliculitis. We also examined cytokine profiles of circulating CD4+ T cells by intracellular cytokine staining and flow cytometry. The ratio of cells positive for interferon-gamma was significantly reduced compared with a control. Several reports have shown decreased interferon-gamma production by peripheral blood mononuclear cells of patients with hyperimmunoglobulin E syndrome. We think that this cytokine profile and the histological findings of our patient support the hypothesis that TH1/TH2 imbalance is involved in hyperimmunoglobulin E syndrome.

Schnitzler's syndrome versus adult onset Still's disease

We report the case of a 50-year-old man with a 4-year history of high spiking fever accompanied by a widespread, urticarial, non-pruritic or only sometimes mildly pruritic eruption and arthralgia. He also had generalized lymphadenopathy, hepatosplenomegaly, and hyperosteoses of the lower lumbar spine. Laboratory examination revealed an elevated erythrocyte sedimentation rate, elevated white blood cell and platelet counts, hypoalbuminemia, and elevated serum IgM with IgM kappa monoclonal immunoglobulin. We diagnosed his condition as Schnitzler's syndrome, in contrast to the diagnosis of adult onset Still's disease, for which he had been initially followed up by his internist. We compare clinical and histopathological findings for both diseases and, as this patient meets two of the six existing diagnostic criteria for adult onset Still's disease, we propose that Schnitzler's syndrome is an important entity to be added to the list of differential diagnoses for adult onset Still's disease.