Detection of linear IgE deposits in bullous pemphigoid and mucous membrane pemphigoid: a useful clue for diagnosis.

BACKGROUND: Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease of the skin associated with IgG autoantibodies to BP180 and BP230, while mucous membrane pemphigoid (MMP) comprises a heterogeneous group of autoimmune blistering diseases characterized by a predominant mucous membrane involvement and scarring tendency associated with an autoantibody response to various autoantigens, including BP180. While the pathogenicity of IgG autoantibodies to BP180 has been demonstrated in BP, the role of IgE autoantibodies in mediating tissue damage in BP and MMP is unclear. OBJECTIVES: To assess the presence of tissue-bound IgE in patients with BP and MMP, and their correlation with distinct clinical features. METHODS: In this retrospective study, we assessed the presence of IgE deposits as detected by direct immunofluorescence microscopy of skin biopsy specimens obtained from 44 and 13 patients with a new diagnosis of BP and MMP, respectively. Distinct clinical features at time of diagnosis, such as itch, urticarial papules and plaques and eczematous lesions, were noted. RESULTS: In 18 of 44 (41%) patients with BP linear deposits of IgE of variable intensity were detectable along the dermoepidermal junction. In 14 (32%) of the cases, IgE deposits were found concomitantly with IgG and C3. In two (5%) patients, diagnosis of BP was based on the isolated detection of IgE together with consistent clinicopathological features. Nine of 13 (69%) patients with MMP also exhibited linear IgE deposits, including one case with isolated linear IgE deposits. Patients with BP with tissue-bound IgE deposits had clinically significant urticarial papules and plaques when compared with patients with BP without IgE deposits. CONCLUSIONS: Our findings indicate that demonstration of tissue-bound IgE deposits provides an additional useful criterion for diagnosis of BP and MMP in some patients. Prospective studies are needed to better correlate the presence of tissue-bound and circulating IgE autoantibodies and their specificity with distinct clinical features and course of BP and MMP.

The -308 tumour necrosis factor-alpha gene polymorphism predicts therapeutic response to TNFalpha-blockers in rheumatoid arthritis and spondyloarthritis patients.

OBJECTIVE: To examine whether the G-to-A polymorphism at position -308 in the promoter of the tumour necrosis factor-alpha (TNFalpha) gene influences the therapeutic response to TNFalpha-blockers in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and ankylosing spondylitis (AS). METHODS: A total of 54 patients with RA, 10 with PsA and 22 with AS were genotyped by polymerase chain reaction for the -308 TNFalpha promoter polymorphism. They were treated with infliximab (n = 63), adalimumab (n = 10) or etanercept (n = 13). Clinical response was assessed after 24 weeks by the Disease Activity Score in 28 joints (DAS28) for RA and PsA, and the Bath Ankylosing Spondylitis Activity Index (BASDAI) for AS patients. RESULTS: All patients with the A/A genotype (n = 3, all RA) and two patients with the A/G genotype (AS) failed to respond to anti-TNF treatment. Irrespective of the underlying disease, moderate response (n = 44) was predominantly associated with the A/G genotype (A/G 18/22, G/G 4/22), whereas good response (n = 59) was exclusively seen in patients with the G/G genotype. The average improvement in the DAS28 score was 0.83 in the A/A, 1.50 in the A/G and 2.64 in the G/G group of RA and PsA patients (P < 0.0001). The BASDAI score in AS improved on average by 1.21 in the A/G and by 3.30 in the G/G group (P < 0.005). CONCLUSIONS: The data suggest that humans with a TNFalpha -308 G/G genotype are better responders to anti-TNFalpha treatment than those with A/A or A/G genotypes independent of the treated rheumatic disease (RA, PsA or AS).

Sequence analysis of the upstream regions of Xenopus laevis beta-globin genes and arrangement of repetitive elements within the globin gene clusters.

The globin gene clusters of Xenopus laevis are interspersed by various different repetitive DNA elements. A specific repeat, the JH12 element, has been mapped by Southern analysis and some of its locations have been subsequently confirmed by nucleotide sequencing. JH12 family members seem to represent mobile genetic elements and display a high degree of divergence. The nucleotide sequences upstream to the adult beta I-globin gene and to the two coordinately expressed larval beta I- and beta II-globin genes have been determined and compared to those of the adult alpha-genes. Besides some repetitive DNA elements and a short sequence of rather weak homology we have found no characteristic sequence motifs to be common to the adult alpha- and beta-genes. The two larval beta-genes share one short sequence element being absent from the adult genes. This might reflect completely different sequence requirements for protein interactions and for the regulation of adult and larval globin gene expression.

Growth factors, lipid mediators and effector cells.

Hematopoetic growth factors stimulate the proliferation of leukocyte precursors in bone marrow cultures, but some also augment the responsiveness of mature effector cells. For example, granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances superoxide production and cytotoxicity of neutrophils stimulated by diverse agonists. We show that preexposure of neutrophils to GM-CSF is absolutely required for the induction of leukotriene B4 and platelet-activating factor (PAF) synthesis by a soluble agonist, C5a or N-formyl-methionyl-leucine-phenylalanine (FMLP). Lipid mediator synthesis occurs very rapidly after triggering with the second signal, and under identical conditions superoxide release is enhanced. Interleukin-3 (IL-3), another hematopoetic growth factor, enhances granule release and more profoundly leukotriene C4 (LTC4) synthesis in basophils stimulated by immunoglobulin-E (IgE)-dependent or -independent agonists. Sequential stimulation with IL-3 and C5a results in the production of large quantities of LTC4, while neither factor alone induces the release of lipid mediators. We conclude that a major function of these cytokines is to allow lipid mediator synthesis in effector cells after triggering with agonists which by themselves do not induce the production of bioactive lipids. We also propose that lipoxygenase metabolites and PAF represent an autocrine response amplification pathway in effector cells which might explain the enhanced responsiveness of cells primed by these cytokines.

Primary structure and evolutionary relationship between the adult alpha-globin genes and their 5'-flanking regions of Xenopus laevis and Xenopus tropicalis.

To investigate the evolution of globin genes in the genus Xenopus, we have determined the primary structure of the related adult alpha I- and alpha II-globin genes of X. laevis and of the adult alpha-globin gene of X. tropicalis, including their 5'-flanking regions. All three genes are comprised of three exons and two introns at homologous positions. The exons are highly conserved and code for 141 amino acids. By contrast, the corresponding introns vary in length and show considerable divergence. Comparison of 900 bp of the 5'-flanking region revealed that the X. tropicalis gene contains a conserved proximal 310-bp promoter sequence, comprised of the canonical TATA and CCAAT motifs at homologous positions, and five conserved elements in the same order and at similar positions as previously shown for the corresponding genes of X. laevis. We therefore conclude that these conserved upstream elements may represent regulatory sequences for cell-specific regulation of the adult Xenopus globin genes.

Lymphokine production by human peripheral blood lymphocytes: analysis by in situ hybridization.

Lymphokine production in human peripheral blood mononuclear cells (PBMNCs) was investigated by in situ hybridization with 35S-labelled RNA probes coding for interleukin 2 (IL-2), gamma-interferon (gamma-IFN) and granulocyte/macrophage colony stimulating factor (GM-CSF). The proportion of PBMNCs expressing lymphokine mRNA varied according to the stimuli used and followed similar patterns to those previously observed by Northern blot analysis. Only a relatively low proportion of PBMNCs expressed lymphokine mRNA after stimulation for a given time, and this seems not to be due to the heterogeneity of T cells.

Conserved sequences and cell-specific DNase I hypersensitive sites upstream from the co-ordinately expressed alpha I- and alpha II-globin genes of Xenopus laevis.

The globin gene family of Xenopus laevis comprises pairs of closely related genes that are arranged in two clusters, each pair of genes being co-ordinately and stage-specifically expressed. To get information on putative regulatory elements, we compared the DNA sequences and the chromatin conformation 5' to the co-ordinately expressed adult alpha-globin genes. Sequence analysis revealed a relatively conserved region from the cap site up to position -289, and further upstream seven distinct boxes of homology, separated by more diverged sequences or deletions/insertions. The homology boxes comprise 22 to 194 base-pairs showing 78 to 95% homology. Analysis of chromatin conformation showed that DNase I preferentially cuts the upstream region of both genes at similar positions, 5' to the T-A-T-A and the C-C-A-A-T boxes, only in chromatin of adult erythroblasts and erythrocytes, where adult globin genes are expressed, but not in chromatin of adult liver cells or larval erythrocytes, where these genes are silent. This suggests that cell- and stage-specific activation of these genes coincides with specific changes in chromatin conformation within the proximal upstream region. No difference was found in the nucleotide sequence within the DNase I hypersensitive region proximal to the adult alpha 1-globin gene in DNA from embryonic cells, in which this gene is inactive, and adult erythrocytes, expressing this gene.