Pemphigoïde du sujet jeune

INTRODUCTION

Bullous pemphigoid usually affects elderly people. Only a few isolated cases among people younger than 65 years have been reported.

OBJECTIVES

Describe the clinical and biological characteristics of patients younger than 60 years suffering from bullous pemphigoid, compare them with the usual characteristics known among elderly people and search for potential pathological associations.

PATIENTS AND METHODS

Retrospective, national, multicenter study. Clinical, biological and histological characteristics were recorded with a standardised questionnaire as well as treatments and associated pathologies.

RESULTS

Seventy-four cases of bullous pemphigoid diagnosed between June 1970 and March 2002 were analyzed. Mean age at the beginning of the disease was 46 +/- 11.6 years. Further explorations by indirect immunofluorescence of separated skin and/or immuno-electron microscopy and/or immunoblotting were performed for 42 patients (56.8 p. 100). Clinical characteristics among this restricted population were comparable to those found among the 32 other cases. Compared to usual data on bullous pemphigoid in elderly people, we observed a greater proportion of extensive form of disease (75 p. 100), a more frequent head and neck involvement (39.2 p. 100) and an overexpression of anti-BP180 autoantibodies (48 p. 100). Neoplasm was notified for 7 patients (9.5 p. 100), 18 (24.3 p. 100) suffered from a pathology of the basement membrane zone (6 psoriasis, 6 atopic dermatitis and 6 lichen) and 13 from neurological disease, among which 4 were bedridden. Fourty-six patients (62.2 p. 100) received drugs for the long term (mean 2.12 +/- 2.43), 4 patients were treated by PUVAtherapy and 2 by radiotherapy.

DISCUSSION

Our results suggest that bullous pemphigoid among young people is more severe and more active than the usual form in the elderly. This particular form could be the result of a higher expression of anti-BP180 autoantibodies, which are considered as a marker of poor prognosis in this disease. We also found a high frequency of pathological associations and physical treatment, all responsible for damage to the basement membrane zone, which can involve auto-immunization against hemidesmosome components.

Early quantitative and functional deficiency of NK1+-like thymocytes in the NOD mouse

An immunoregulatory role has recently been attributed to the discrete subset of major histocompatibility complex class I-restricted NK1+ mature heat-stable antigen- (HSA-) thymocytes expressing an unusual Vbeta8-biased T cell receptor repertoire. NK1+ T cells are the main interleukin (IL)-4 producers upon priming. We have studied the size and the function of this subset in the nonobese diabetic (NOD) mouse, a model of spontaneous T cell-mediated autoimmune insulin-dependent diabetes. This study was complicated by the absence in this strain of the NK1.1 allele, the only one for which an antibody is available. To circumvent this difficulty, the cells, hereafter designated the NK1+-like T subset, were characterized by the use of monoclonal antibodies which showed the Vbeta8 bias in the CD44+ Ly-49+ MEL-14- 3G11- thymocyte subset of non-autoimmune strains and of its absence in class I-deficient (beta2-microglobulin-/-) mice. A clear deficit in the number of NK1+-like cells was evidenced at 3 weeks of age in NOD mice. It was still present at 8 weeks of age in the double-negative CD4-CD8- population. The functional anomaly was even more striking: NOD mouse NK1+-like thymocytes virtually lacked the ability to produce IL-4 at 3 weeks and still showed a very reduced capacity at 8 weeks. NK1+ T cell deficiency was also suggested in the periphery by the reduction of Ly-49A+ cells in the spleen of 3- and 8-week-old NOD mice and the absence of short-term production of IL-4 in vitro by NOD mouse spleen cells 90 min after the administration of anti-CD3 antibody, a response attributed to NK1+ T cells. Taken together, these data demonstrate a very early defect in NK1+-like T cells which could be involved in the genesis of autoimmunity in NOD mice through a deficiency in Th2 cell function.

IL-7 reverses NK1+ T cell-defective IL-4 production in the non-obese diabetic mouse

Converging data suggest an important role for IL-7 in T lymphocyte maturation as illustrated by the severe T lymphopenia observed in IL-7-deficient mice. We recently reported that IL-7 preferentially promotes the in vitro expansion of a discrete MHC class I-dependent lymphocyte subset comprising both CD4+ and CD4-CD8- TCR alpha beta + cells bearing several NK cells markers such NK1.1 and Ly-49. These T cells, designated as NK1+ T cells, have the unique property among thymocytes of producing large amounts of IL-4 upon primary stimulation via the TCR. We have further demonstrated that thymic NK1+ T cells of non-obese diabetic (NOD) mice, a spontaneous model of autoimmune type I diabetes, are markedly deficient in maturation both quantitatively and functionally (IL-4 production). In the present experiments, the addition of exogenous IL-7 completely restored IL-4 production by anti-TCR alpha beta-stimulated mature (HSA-CD8-) thymocytes in NOD mice. A short 2 h preincubation with IL-7 was sufficient to restore both the expression of IL-4 mRNA and IL-4 production capacity. This was related to a direct effect on NK1+ thymocytes since: (i) the effect of IL-7 was restricted to the non-mainstream MEL-14- 3G11- TCR alpha beta + subset which mostly concentrates the IL-4-producing capacity and (ii) IL-7 did not restore IL-4 production in class I-deficient mice which lack the NK1+ T cell subset. Importantly, this activity of IL-7 on NK1+ T cells was also demonstrated in non-autoimmune strains of mice. These results were extended in vivo by showing that the IL-7 treatment significantly increased the anti-CD3 triggered IL-4 production by NK1+ T spleen cells. These findings confirm the role of IL-7 in NK1+ T cell maturation and suggest that the NK1+ T cell defect in NOD mice could be related to insufficient intrathymic IL-7 bioavailability.

Early defect of immunoregulatory T cells in autoimmune diabetes

A potential immunoregulatory function has recently been attributed to the discrete subset of major histocompatibility complex (MHC) class I-restricted TCR-alpha beta mature thymocytes expressing an unusual V beta 8-biased T cell receptor repertoire. This T cell subset which also selectively express the CD44 marker is the main IL-4 producer in the thymus. Nonobese diabetic (NOD) mice were found to have a marked deficit in the number and functional capacity of CD44+ TCR-alpha beta+ thymocytes from as early as 3 weeks of age. The deficiency in IL-4 production was completely corrected after incubation with interleukin-7 (IL-7), a selective growth factor for CD44+ TCR-alpha beta+ mature thymocytes. This abnormality in T cell differentiation could explain the Th2 functional deficiency that may be a key element in the emergence of Th1-driven autoimmune disease in NOD mice.