Sulphite oxidase (SO) - a mitochondrial autoantigen as target for humoral and cellular immune reactions in primary sclerosing cholangitis.

BACKGROUND: In a recent study we had evidence that sulphite oxidase (SO) may be a relevant autoantigen in primary sclerosing cholangitis (PSC). Aim of the present study was, therefore, to analyse humoral and cellular immune-reactivity towards SO in these patients in more detail. METHODS: Sera from 53 patients with PSC (30 untreated and 23 treated with ursodeoxycholic acid [UDCA] at time of analysis), from 422 patients with different hepatic and non-hepatic disorders, and from 50 healthy individuals were tested by ELISA for antibodies against full-length-SO (SO-fl) and its three major domains expressed in E.coli (SO-I, SO-II, SO-III). For epitope-mapping, 29 overlapping peptides were used. Peripheral blood mononuclear cells (PBMC) were obtained from 33 PSC-patients and analysed for SO-induced proliferation, production of cytokines, and expression of the activation marker cluster of differentiation (CD) 69. RESULTS: 43% of the 30 untreated and 26% of the 23 treated PSC-patients had IgG anti-SO-antibodies predominantly reacting with SO-fl, SO-I and SO-II. Antibody-reactivity decreased after UDCA-treatment. Prevalence and reactivity of anti-SO-antibodies were significantly higher in PSC than in patients with other hepatic and non-hepatic disorders. Epitope mapping revealed no distinct immuno-dominant regions within SO. Incubation of PBMC from PSC-patients (but not from controls) with SO-antigens revealed an activation of B-cells and a T-helper cell type-2 reaction pattern (production of interleukin [IL]-13, IL-10). CONCLUSIONS: PSC-patients show humoral and cellular immune response towards SO. Antibodies may be predominantly directed against conformational epitopes. SO enhances in vitro especially T-helper cell type-2 immune-reactions, which may be pro-fibrotic. SO is a detoxifying enzyme present also in bacteria; further studies analysing its role in the aetiology and pathogenesis in PSC may, therefore, be important.

Effect of buckminsterfullerenes on cells of the innate and adaptive immune system: an in vitro study with human peripheral blood mononuclear cells.

C60 nanoparticles, the so-called buckminsterfullerenes, have attracted great attention for medical applications as carriers, enzyme inhibitors or radical scavengers. However, publications evaluating their immunological mechanisms are still rather limited. Therefore, we aimed to analyze systematically the in vitro influence of polyhydroxy-C60 (poly-C60) and N-ethyl-polyamino-C60 (nepo-C60) on peripheral blood mononuclear cells (PBMC) from healthy individuals, angling their effect on proliferation, expression of surface markers, and cytokine production. We isolated PBMC from 20 healthy subjects and incubated them in a first step only with poly-C60 or nepo-C60, and in a second step together with recall antigens (purified protein derivative, tetanus toxoid, bacillus Calmette-Guérin). Proliferation was determined by (3)H-thymidine incorporation, activation of PBMC-subpopulations by flow cytometry by measurement of the activation marker CD69, and secretion of T helper cell type 1 (TH1)- (interferon-gamma [IFN-γ], tumor necrosis factor beta [TNF-ß]), TH2- (interleukin-5 [IL-5], -13, -10) and macrophage/monocyte-related cytokines (IL-1, IL-6, TNF-α) into the supernatants by enzyme-linked immunosorbent assay. Both fullerenes did not influence T cell reactivity, with no enhanced expression of CD69 and production of T cell cytokines observed, the CD4/CD8 ratio remaining unaffected. In contrast, they significantly enhanced the release of IL-6 and CD69-expression by CD56 positive natural killer cells. PBMC, which had been cultured together with the three recall antigens were not affected by both fullerenes at all. These data indicate that fullerenes do not interact with T cell reactivity but may activate cells of the innate immune system. Furthermore, they seem to act only on 'naïve' cells, which have not been prestimulated with recall antigens, there are however, large inter individual differences.

Differential effects of the tumor necrosis factor alpha-blocker infliximab and etanercept on immunocompetent cells in vitro.

The tumor necrosis factor-alpha (TNFα) antagonists infliximab or etanercept are used in the management of chronic inflammatory disorders but have differences in clinical activity. Here we show that both have different effects on immunocompetent cells in vitro. Peripheral blood mononuclear cells (PBMC) from 20 healthy donors were incubated with infliximab or etanercept alone and in a co-culture with recall-antigens (BCG, tetanus toxoid [TT]). Expression of the activation marker CD69 on different PBMC-subpopulations was determined by flow cytometry, release of Th1-, Th2- and macrophage/monocyte-related cytokines into the supernatants by ELISA. There were strong inter-individual differences in reactivity of PBMC of the 20 donors towards infliximab and etanercept. On the whole group level, both enhanced IL-10 production but had opposite effects on the TNFα- and IFNγ-secretion; Th2-cytokine-secretion (IL-13, IL-5) was differentially influenced. IL-13 production was significantly reduced by infliximab but not by etanercept. IL-5 secretion was strongly enhanced in individual subjects but was not significantly influenced on the whole group level. Etanercept but not infliximab significantly decreased the CD69-expression by CD8+ T- and CD56+ natural killer(NK)-cells. Co-culture with recall antigens enhanced most of these reactions. Our data indicate that individual predisposition and immunological reactivity may be an important factor influencing the therapeutic efficacy of anti-TNFα agents.