Paratope- and framework-related cross-reactive idiotopes on anti-acetylcholine receptor antibodies

Cross-reactive idiotopes are a possible target for therapeutical interventions in autoimmune diseases. To investigate their role in the pathogenesis of experimental autoimmune myasthenia gravis (EAMG) we analyzed the Id of rat anti-AChR mAb 6, 35, 61, 65 and a control myeloma protein IR27. Anti-Id 6, 35, 61, 65 bound in a direct binding assay with various affinity to all rat anti-AChR mAb that were tested. Anti-Id IR27 recognized none of the anti-AChR mAb. The specificity of these crossreactions was confirmed by inhibition studies with anti-AChR mAb and two control rat myeloma proteins (IR27 and IR241). In addition, the Id expression on mAb D6, a mouse anti-human AChR mAb was recognized by anti-Id 6, 35, and 65. Anti-Id, except anti-Id IR27, bound to affinity purified IgG from the sera of rats with EAMG, but not to preimmune Lewis IgG. These results suggest extensive sharing of idiotopes among anti-AChR mAb, which are also present in EAMG serum. Anti-AChR mAb against the main immunogenic region (6, 35, 65) from different rat strains, shared at least one paratope-related cross-reactive idiotopes. In the view of the fact that anti-main immunogenic region antibodies might form a predominant fraction of the polyclonal response against AChR, it is conceivable that an anti-Id recognizing these antibodies could have therapeutical applications as for example a selective immune absorbent or in immunotoxin therapy.     

The origin of transfer of P307

The DNA fragment carrying the oriT region from the enterotoxin plasmid P307 was isolated and its polynucleotide sequence was determined. Using Southern hybridization assays with a synthetic oligonucleotide probe, the oriT region was identified on a 7.9-kb EcoRI fragment from P307. By ligating the fragment with the cloning vector pUC119, plasmid pAG10 was obtained. The physical map of the insert was determined and oriT was located on a 540-bp BglII/SalI fragment. After this fragment was subcloned into sequencing phages, the polynucleotide sequence was established. Part of the sequence proved to be almost identical to segments of the oriT regions of the plasmids F and R1; another neighboring region was very different among all three sequences. The polynucleotide sequence proximal to traM is highly similar to that of F but different from that of R1.     

Sequence variation in a newly identified HLA-B35-restricted epitope in the influenza A virus nucleoprotein associated with escape from cytotoxic T lymphocytes

Here, we describe a new HLA-B*3501-restricted cytotoxic T lymphocyte (CTL) epitope in the influenza A virus (H3N2) nucleoprotein, which was found to exhibit a high degree of variation at nonanchor residues. The influenza virus variants emerged in chronological order, and CTLs directed against old variants failed to recognize more recent strains of influenza A virus, indicating an escape from CTL immunity.     

Real‐time monitoring of herbivore induced volatile emissions in the field

When plants are damaged by herbivorous insects they emit a blend of volatile organic compounds (VOCs) which include a range or terpenoids and green leaf volatiles (GLVs) formed via different metabolic pathways. The precise timing of these emissions upon the onset of herbivore feeding has not been fully elucidated, and the information that is available has been mainly obtained through laboratory based studies. We investigated emissions of VOCs from Populus tremula L. ×P. tremuloides Michx. during the first 20 h of feeding by Epirrita autumnata (autumnal moth) larvae in a field site. The study was conducted using Proton Transfer Reaction‐Mass Spectrometry (PTR‐MS) to measure emissions online, with samples collected for subsequent analysis by complementary gas chromatography‐mass spectrometry for purposes of compound identification. GLV emission peaks occurred sporadically from the outset, indicating herbivore activity, while terpene emissions were induced within 16 h. We present data detailing the patterns of monoterpene (MT), GLV and sesquiterpene (SQT) emissions during the early stages of herbivore feeding showing diurnal MT and SQT emission that is correlated more with temperature than light. Peculiarities in the timing of SQT emissions prompted us to conduct a thorough characterization of the equipment used to collect VOCs and thus corroborate the accuracy of results. A laboratory based analysis of the throughput of known GLV, MT and SQT standards at different temperatures was made with PTR‐MS. Enclosure temperatures of 12, 20 and 25°C had little influence on the response time for dynamic measurements of a GLV or MT. However, there was a clear effect on SQT measurements. Elucidation of emission patterns in real‐time is dependent upon the dynamics of cuvettes at different temperatures.     

An Optimized Immunohistochemistry Technique Improves NMO-IgG Detection: Study Comparison with Cell-Based Assays

Cell-based assays (CBA) have increased the sensitivity of the neuromyelitis optica (NMO)-IgG/aquaporin-4-antibody detection compared to classical tissue-based indirect assays. We describe the sensitivity of an optimized immunohistochemistry (IHC-o) to detect NMO-IgG/aquaporin-4-antibody in comparison with that of two CBA: an in-house (CBA-ih) and a commercial (CBA-c) assay (Euroimmun, Germany). Coded serum from 103 patients with definite NMO and 122 inflammatory controls were studied by IHC-o, CBA-ih, and CBA-c. IHC-o used the same protocol described to detect antibodies against cell surface antigens. CBA-ih used live cells transfected with the aquaporin-4-M23-isoform. The sensitivity of the IHC-o was 74.8% (95% confidence interval [CI] 65-83) and was similar to that of the CBA-ih 75.7% (95% CI 66-84) and the CBA-c 73.8% (95% CI 64-82). The specificity of the three assays was 100% (95% CI 97-100). Interassay concordance was high, 100 of 103 samples were coincident in all techniques. The optimized immunohistochemistry proves to be as sensitive and specific as the cell-based assays. This assay extends the available tools for NMO-IgG/aquaporin-4-antibody detection.     

A monoclonal antibody that induces T cell aggregation reacts with vascular endothelial cells and placental trophoblasts

We have found that a mouse monoclonal antibody (alpha Leu-13) to a 16 kilodalton human lymphocyte surface antigen reacts with vascular endothelial cells as determined by immunoperoxidase staining of frozen tissue sections. In earlier studies, alpha Leu-13 was found to induce purified T cells to aggregate when added to cultures in nanogram concentrations. In the studies reported here, alpha Leu-13 stained vascular endothelial cells of arteries, capillaries, and veins in all organs examined from adults. It also reacted weakly with epithelial cells of proximal tubules of the kidney and with nonkeratinized basal epithelial cells of the cervix and esophagus. When a panel of tissues from a 14-wk-old fetus was examined, alpha Leu-13 was not found to react with endothelial cells of any specimen. However, it did stain medullary thymocytes and placental trophoblasts of this fetus. The implications of these findings to the possible function of the Leu-13 antigen in immune ontogeny are discussed.     

Nanoscopic cell-wall architecture of an immunogenic ligand in Candida albicans during antifungal drug treatment

The cell wall of Candida albicans is composed largely of polysaccharides. Here we focus on β-glucan, an immunogenic cell-wall polysaccharide whose surface exposure is often restricted, or “masked,” from immune recognition by Dectin-1 on dendritic cells (DCs) and other innate immune cells. Previous research suggested that the physical presentation geometry of β-glucan might determine whether it can be recognized by Dectin-1. We used direct stochastic optical reconstruction microscopy to explore the fine structure of β-glucan exposed on C. albicans cell walls before and after treatment with the antimycotic drug caspofungin, which alters glucan exposure. Most surface-accessible glucan on C. albicans yeast and hyphae is limited to isolated Dectin-1–binding sites. Caspofungin-induced unmasking caused approximately fourfold to sevenfold increase in total glucan exposure, accompanied by increased phagocytosis efficiency of DCs for unmasked yeasts. Nanoscopic imaging of caspofungin-unmasked C. albicans cell walls revealed that the increase in glucan exposure is due to increased density of glucan exposures and increased multiglucan exposure sizes. These findings reveal that glucan exhibits significant nanostructure, which is a previously unknown physical component of the host–Candida interaction that might change during antifungal chemotherapy and affect innate immune activation.     

The Barrier Reef sediment apron: Tobacco Reef,Belize

Sedimentological and biological surveys of the back-reef sediment apron of Tobacco Reef, a continuous segment of the Belizean Barrier Reef, reveal five distinct biogeological zones: (1) coralline-coral-Dictyota pavement, (2) Turbinaria-Sargassum rubble, (3) Laurencia-Acanthophora sand and gravel, (4) bare sand and 95 Thalassia sand. These zones parallel the entire 9-km reef. The distribution of these zones is related to the spatial patterns of fish herbivory, the size of bottom sediments, and the stability of the substrate. Sedimentological and hydrodynamic studies indicate that most of the sediments in this area are transported from the reef crest and fore reef during periods of storm or hurricane activity and that their size distribution is largely the result of differential transport by high bottom-water velocities during those periods.