Detection of serum anti-melanocyte antibodies and identification of related antigens in patients with vitiligo.

We detected autoantibodies against melanocytes in serum samples obtained from 50 patients, including 4 with HBV, with vitiligo and identified the associated membrane antigens. Heat shock protein 70 (HSP70) and anti-tyrosinase-related protein 1 (TRP-1) antibody levels were analyzed. The associated antigens in normal human melanocyte were identified by immunofluorescence. Autoantibodies against melanocyte membrane and cytoplasmic proteins were detected by western blot. Membrane antigens with higher frequencies were identified by protein mass spectrometry. The HSP70 and anti-TRP-1 antibody levels (N = 70; 10 with HBV) were detected by ELISA. The specific antigens were detected in melanocyte cytoplasm and membrane (40/50; 80% incidence; western blot). The autoantibodies reacted with several membrane antigens with approximate molecular weights (Mr) of 86,000, 75,000, 60,000, 52,000, and 44,000 (strip positive rates: 36, 58, 22, 2, and 2%, respectively). Thirty percent of the patients showed the presence of cytoplasmic antigens (Mr: 110,000, 90,000, 75,000, 50,000, and 400,000; strip positive rates: 12, 4, 12, 10, and 2%, respectively). Fifteen and 5% of the healthy subjects showed positive expression of membrane and cytoplasmic antigens, respectively. Protein mass spectrometry predicted membrane proteins with Mr of 86,000 and 75,000 and 60,000 to be Lamin A /C and Vimentin X1, respective. High titers of anti-TRP-1 antibody were detected and showed positive correlation with HSP70 (r = 0. 927, P < 0. 01). This study identified a novel membrane antigen associated with vitiligo, which might assist future investigations into autoimmune pathogenesis of vitiligo and formation of autoantibodies. HBV infection was correlated to vitiligo.

B-cell epitopes of antigenic proteins in Leishmania infantum: an in silico analysis.

Serodiagnosis of visceral leishmaniasis is often hindered by cross-reactions to other parasitic diseases. Identifying specific B-cell epitopes in proteins is therefore important for immunodiagnostics, as well as for disease control by vaccines. This study aimed to identify linear and conformational B-cell epitopes and to evaluate the secondary structure of antigen proteins in Leishmania infantum using in silico analysis. Linear epitopes were predicted using the Immune Epitope Database and Analysis Resource (IEDB), BepiPred and BcePred programs. The conformational B-cell epitopes were identified using the CBTOPE server. The combination of the predictions using IEDB, BepiPred and BcePred generated 148 linear epitopes from the calpain-like cysteine peptidase (CP), thiol-dependent reductase 1 (TDR1) and HSP70 proteins. In total, 164 conformational epitopes were predicted, mostly located in the linear epitope region. The predicted epitopes are located in α helix and random coil regions in the thiol-dependent reductase 1 and HSP70 proteins. New linear and conformational B-cell epitopes of L. infantum proteins were identified in silico, and the prediction using various programs ensures greater accuracy of the results, as suggested by confirmation of previously identified HSP70 epitopes.

Oxidative and nitrosative stress on phagocytes' function: from effective defense to immunity evasion mechanisms.

Although oxygen, nitrogen, and chlorine reactive species have been associated with disease pathogenesis, their partial absence is very harmful to the body's innate immune defense. Lacking of adequate release of free radicals from activated phagocytes is related to impaired ability on fungi, bacteria, and protozoa killing. We constructed an updated conceptual landmark regarding the paramount role of free radicals in phagocyte defense systems (phagocyte oxidase, myeloperoxidase, and nitric oxide/peroxynitrite system) on natural immunity. Diverse fungal, bacterial and protozoal pathogens evade the phagocytes' oxidative/nitrosative burst though antioxidant genes, enzymes and proteins. The most important evasion mechanisms were also described and discussed. These interconnected systems were reviewed and discussed on the basis of knowledge from relevant research groups around the globe. Phagocyte-derived free radicals are essential to destroy important human pathogens during the course of innate immunity.

Tissue distribution of quiescin Q6/sulfhydryl oxidase (QSOX) in developing mouse.

Quiescin Q6/sulfhydryl oxidases (QSOX) are revisited thiol oxidases considered to be involved in the oxidative protein folding, cell cycle control and extracellular matrix remodeling. They contain thioredoxin domains and introduce disulfide bonds into proteins and peptides, with the concomitant hydrogen peroxide formation, likely altering the redox environment. Since it is known that several developmental processes are regulated by the redox state, here we assessed if QSOX could have a role during mouse fetal development. For this purpose, an anti-recombinant mouse QSOX antibody was produced and characterized. In E(13.5), E(16.5) fetal tissues, QSOX immunostaining was confined to mesoderm- and ectoderm-derived tissues, while in P1 neonatal tissues it was slightly extended to some endoderm-derived tissues. QSOX expression, particularly by epithelial tissues, seemed to be developmentally-regulated, increasing with tissue maturation. QSOX was observed in loose connective tissues in all stages analyzed, intra and possibly extracellularly, in agreement with its putative role in oxidative folding and extracellular matrix remodeling. In conclusion, QSOX is expressed in several tissues during mouse development, but preferentially in those derived from mesoderm and ectoderm, suggesting it could be of relevance during developmental processes.

An analysis of the topography of molecular forms 1 and 3 of rat liver biliverdin reductase using polyclonal antibodies.

Rat liver biliverdin reductase exists in two molecular forms. The major one (molecular form 1) is transformed, under conditions of oxidative stress into another molecular form (molecular form 3) which is an S-S bridged dimer of form 1. The chemical modifications of the thiol, arginine and lysine residues of molecular form 1 which resulted in an inhibition of its catalytic activity did not affect the activity of molecular form 3. Rabbit polyclonal antibodies raised against form 1 did not recognize form 3. This lack of recognition persisted even when the dimer (form 3) was denatured with SDS or urea under non-reductive conditions. Reduction of form 3 with reduced thioredoxin gave the monomeric form 1, which was fully recognized by the antibodies. The latter recognized the biliverdin reductases from rat spleen and kidney to the same extent as they did with form 1. Molecular form 1 was completely inhibited by the addition of the antibodies. This inhibition was prevented by preincubation of the enzyme with either the substrate (biliverdin) or the cosubstrate (NADPH). Preincubation with the latter or with NADP+ (but not with bilirubin) strongly impaired the recognition of form 1 by the antibodies. Modification of the lysine or arginine residues of form 1 which were involved in substrate binding, impaired the interaction of the enzyme with the antibodies. The antisera blocked the enzymatic conversion of form 1 to form 3, but alkylation of the thiol residue involved in this dimerization had no effect on the interaction of form 1 with the antibodies. The lack of recognition of form 3 by the antibodies suggest that the antigenic site of the former becomes buried upon dimerization.