Microsolvation in superfluid helium droplets studied by the electronic spectra of six porphyrin derivatives and one chlorine compound.

After almost two decades of high resolution molecular spectroscopy in superfluid helium droplets, the understanding of microsolvation is still the subject of intense experimental and theoretical research. According to the published spectroscopic work including microwave, infrared, and electronic spectroscopy, the latter appears to be particularly promising to study microsolvation because of the appearance of pure molecular transitions and spectrally separated phonon wings. Instead of studying the very details of the influence of the helium environment for one particular dopant molecule as previously done for phthalocyanine, the present study compares electronic spectra of a series of non-polar porphyrin derivatives when doped into helium droplets consisting of 10(4)-10(5) helium atoms. Thereby, we focus on the helium-induced fine structure, as revealed most clearly at the corresponding electronic origin. The interpretation and the assignment of particular features obtained in the fluorescence excitation spectra are based on additional investigations of dispersed emission spectra and of the saturation behavior. Besides many dopant-specific results, the experimental study provides strong evidence for a particular triple peak feature representing the characteristic signature of helium solvation for all seven related dopant species.

Electronic spectroscopy of molecules in superfluid helium nanodroplets: an excellent sensor for intramolecular charge redistribution.

Electronic spectra of molecules doped into superfluid (4)He nanodroplets reveal important details of the microsolvation in superfluid helium. The vibrational fine structure in the electronic spectra of phthalocyanine derivatives and pyrromethene dye molecules doped into superfluid helium droplets have been investigated. Together with previous studies on anthracene derivatives [J. Chem. Phys.2010, 133, 114505] and 3-hydroxyflavone [J. Chem. Phys.2009, 131, 194307], the line shapes vary between two limiting cases, namely, sharp Lorentzians and nonresolved vibrational fine structure. All different spectral signatures are initiated by the same effect, namely, the change of the electron density distribution initiated by the electronic excitation. This change can be quantified by the difference of the electrostatic moments of the molecule in the electronic ground state and the corresponding Franck-Condon point in the excited state. According to the experimental data, electronic spectroscopy suffers from drastic line broadening when accompanied by significant changes of the charge distribution, in particular, changes of the dipole moment. Vice versa, the vibrational fine structure in electronic spectra of molecules doped into helium droplets is highly sensitive to changes of the electron density distribution.

Intramedullary spinal sarcoidosis: clinical improvement reflected in T-lymphocyte subpopulation ratios.

STUDY DESIGN: Case report. OBJECTIVES: A case report of spinal sarcoidosis improving clinically and radiographically with treatment which correlated with improvement in cerebrospinal fluid T-lymphocyte subpopulation ratios. SETTING: Walter Reed Army Medical Center. CASE REPORT: A 46-year-old man presented with an enhancing spinal cord lesion. Lymph node biopsy confirmed sarcoidosis, and cerebrospinal fluid (CSF) analysis showed elevation in the ratio of two T-lymphocyte subpopulations. Treatment with steroids resulted in clinical resolution and immunocytologic improvement in the CSF.

The humanized SCID mouse model to study HLA class II-linked autoimmunity to desmoglein 3 in pemphigus vulgaris.

BACKGROUND: Pemphigus vulgaris (PV) is a severe autoimmmune skin disorder induced by antibodies against desmoglein (Dsg) 3 on epidermal keratinocytes. OBJECTIVES: To establish an active animal model of PV to analyse the T-cell-regulated production of pathogenic antibodies in vivo. METHODS: Immunodeficient SCID mice were injected with peripheral blood lymphocytes (PBL) from an HLA-DRB1*0402/DQ8+ patient with PV or a DRB1*0402/DQ8+ healthy donor, with or without subsequent injections of human Dsg3 or preincubation of PBL with Dsg3. RESULTS: Human immunoglobulins (2.7-18.5 mg mL-1) were detected in all the mice after 8 weeks. Only one of 30 PBL-treated mice developed IgM against Dsg3 and showed intercellular IgM deposits in skin, nostrils and tongue. In contrast, in a previous study, 41% of SCID mice injected with PBL from patients with PV developed anti-Dsg3 antibodies in vivo. CONCLUSIONS: Our inability to reproduce these findings may be due to the transfer of slightly lower numbers of PBL (20 x 10(6) vs. 25-30 x 10(6)).

IgG, IgA and IgE autoantibodies against the ectodomain of desmoglein 3 in active pemphigus vulgaris.

BACKGROUND: IgG autoantibodies against desmoglein (Dsg) 3 play a key part in the pathogenesis of pemphigus vulgaris (PV), the most severe autoimmune bullous disorder. OBJECTIVES: To determine whether immunoglobulin isotypes other than IgG are detectable in the sera of patients with PV and whether a particular immunoglobulin subtype is associated with a distinct clinical phenotype of PV. METHODS: Sera from 41 patients with acute-onset, chronic active, and remittent PV disease with mucosal and cutaneous lesions were assayed against a baculovirus-expressed Dsg3 protein by immunoblot analysis. RESULTS: In acute-onset PV, Dsg3-reactive IgG1 was detected in nine of 15 (60%), IgG4 in 14 of 15 (93%), IgA in nine of 15 (60%) and IgE in two of 15 (13%) sera. In chronic active PV, Dsg3-reactive IgG1 was detected in 11 of 18 (61%), IgG4 in 16 of 18 (89%), IgA in 13 of 18 (72%) and IgE in two of 18 (11%) sera. In contrast, sera from patients with remittent PV disease contained only Dsg3-reactive IgG1 in six of eight (75%) and IgG4 in four of eight (50%) cases, but not Dsg3-reactive IgA or IgE. CONCLUSIONS: In extension of previous findings, our study demonstrates that, in addition to IgG autoantibodies, IgA and occasionally IgE autoantibodies reactive with Dsg3 are present in acute and chronic active PV. The detection of Dsg3-reactive autoantibodies of the IgG4, IgA and IgE subclasses in active PV provides additional evidence that PV is a T-helper 2-regulated autoimmune disorder.

Frequency analysis of autoreactive T-helper 1 and 2 cells in bullous pemphigoid and pemphigus vulgaris by enzyme-linked immunospot assay.

BACKGROUND: Bullous pemphigoid (BP) and pemphigus vulgaris (PV) are autoimmune bullous skin diseases mediated by autoantibodies against adhesion molecules of the skin. Previous studies have identified autoreactive T cells in patients with BP and PV, which may be critical in providing B-cell help for autoantibody production. OBJECTIVES: To evaluate the frequency of autoreactive T-helper (Th) 1 and Th2 cells in patients with BP (n = 7) or PV (n = 1) and in healthy controls (n = 11). METHODS: In an enzyme-linked immunospot (ELISPOT) assay, microtitre plates were coated with antihuman interleukin (IL)-5 IgG or antihuman interferon (IFN)-gamma IgG prior to culturing human peripheral blood lymphocytes (PBL) with BP180 or desmoglein (Dsg) 3 proteins for 7 days. Cytokine-producing autoreactive T cells were visualized as spot-forming units. RESULTS: One BP patient with extensive blisters had 5.1 +/- 1.5 (mean +/- SD) BP180-reactive Th1 cells and 2.9 +/- 1.5 Th2 cells per 105 PBL. In contrast, PBL from six BP patients in remission or on immunosuppressive therapy did not form IFN-gamma- or IL-5-producing spots per

HLA class II restriction of autoreactive T cell responses in pemphigus vulgaris: review of the literature and potential applications for the development of a specific immunotherapy.

Pemphigus vulgaris (PV) is a life-threatening autoimmune bullous disease of the skin and mucous membranes which requires immunosuppressive therapy, most commonly a combination of glucocorticoids and additional immunosuppressive agents. Since the side effects of long-term immunosuppressive therapy contribute to the poor prognosis of this disorder, there is considerable interest in a more specific treatment of this severe skin disease. PV may serve as a model disease for the development of a specific immunotherapy, because its pathogenesis as well as involved immunogenetic factors are well-characterized. This review focuses on the characterization of autoreactive T cell responses to desmoglein 3 (Dsg3), the autoantigen of PV, that presumably regulate the production of autoantibodies by providing help to the autoreactive B cells. Current knowledge on T cell epitopes of Dsg3 and the HLA class II alleles that restrict Dsg3-specific autoreactive T cell responses, as well as potential applications for a specific immunotherapy of PV, are described.

Analysis of the T cells that are potentially involved in autoantibody production in pemphigus vulgaris.

Pemphigus vulgaris (PV) is a classical example of an antibody-mediated autoimmune disease of the skin. Direct evidence exists that autoantibodies against the desmosomal adhesion molecule, desmoglein 3 (Dsg3), are critical in the pathogenesis of this disease. The transfer of serum IgG antibodies reactive with Dsg3 into newborn mice induces a bullous skin disease resembling PV. Autoreactive T cell responses to Dsg3 may be critical in the pathogenesis of PV because 1) antibody production generally requires T cell help, 2) the involvement of CD4+ T lymphocytes in PV has been suggested by the strong association with distinct HLA class II alleles, and 3) T cell recognition of epitopes of Dsg3 may be crucial for the initiation and perpetuation of the production of Dsg3-specific autoantibodies by B cells. We and others have identified autoreactive T cells recognizing distinct epitopes of the extracellular portion of Dsg3 in PV patients. These autoreactive CD4+ T cells preferentially produced TH2 cytokines such as IL-4, and IL-10. Autoantibodies of the TH2-dependent IgG4 subtype are preferentially seen in active stages of PV disease, while autoantibodies of the TH1-dependent IgG1 subclass are predominant upon remission of PV. Healthy individuals who carried HLA class II alleles similar or identical to those found to be highly prevalent in PV also developed autoreactive T cell responses to Dsg3. Autoreactive T cells from PV patients produced both TH1 and TH2 cytokines; autoreactive T cells from normals produced TH0 cytokines. These observations suggest that Dsg3-specific T cells may provide targets to eventually modulate the T cell-dependent production of pathogenic autoantibodies in PV.