Male—female recognition in flowering plants is initiated by mutual contact of pollen and stigma surface components. Analysis of the surface macromolecules of both stigma and pollen of Gladiolus gandavensis revealed a complex mixture of proteins, glycoproteins, and glycolipids. The carbohydrate-containing components amounted to 6% in pollen and 23% in stigma and contained the monosaccharides galactose, arabinose, glucose, mannose, and rhamnose. All the mannose of both preparations was associated with a fraction that bound to concanavalin A. The stigma surface contained an arabinogalactan or arabinogalactan protein as a major component. This component has been isolated by affinity chromatography on tridacnin-Sepharose and shown to be similar in composition to a style canal component isolated in the same way. The capacity of the stigma surface preparations to bind nonspecifically to macromolecules from pollen and other sources has been demonstrated in vivo and in vitro . Specific binding of concanavalin A to the stigma surface decreases the adhesive capacity for pollen protein. The arabinogalactan of the stigma surface may act as an adhesive base. The pollen and stigma surfaces apparently complement one another to provide all the components of an ideal adhesive.

The interaction between compatible pollen grains and the female stigma of Gladiolus gandavensis has been used as a model system for investigation of cell recognition in plants. The Cells of virtually all eukaryotic organisms possess some capacity to distinguish self from not-self (1). Processes reflecting this recognition capacity have been extensively explored in animal systems (2), but plants have been largely neglected. However, recognition between compatible pollen and the female stigma in plants provides a model system for cell recognition which is genetically specified (3), and in which transfer of information has been demonstrated both for pollen, which carries the male gametes (4), and the stigma surface (5). In this communication we describe the recognition events in the self-compatible system of Gladiolus, whose pollen walls are known to contain a range of proteins in both exine and intine sites (6). We have investigated the molecular architecture of the external stigma surface with a view to demonstrating surface receptors. (7) showed that the dialyzed and dried extract contained 25% sodium deoxycholate and 17% MATERIALS AND METHODS

By the use of limited trypsin digestion of purified virions, we generated a membrane anchor-free and crystallizable form of the tick-borne encephalitis virus envelope glycoprotein E. It retained its reactivity with a panel of monoclonal antibodies, and only subtle structural differences from the native protein E were recognized. Treatment with the bifunctional cross-linker dimethylsuberimidate resulted in the formation of a dimer. Crystallization experiments yielded hexagonal rod-shaped crystals suitable for X-ray diffraction analysis.

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Aim: The objective of this study was compare the in vivo distribution of different preparations of dendritic cells (DC) from a single donor after intradermal (ID) administration and correlate FACS analysis of excised tissue and imaging findings. Method: DC were generated from a single healthy donor apheresis product. The DC types were GM-CSF + IL-13 (IL-13 imDC), then further matured with FMKp+IFNg (IL-13mDC), GM-CSF + IL-4 (IL-4 imDC) and matured (IL-4 mDC) and GM-CSF+IFN-α (IFN-α DC). Antigen naive DC preparations were labelled with Yttrium-86 oxine (prepared on site) by incubation at room temperature for 30 minutes followed by centrifugation and resuspension. 5 × 105 radio-labelled cells in 50_L was injected ID into the footpad and the volar aspect of the foreleg of Balb/c nude mice (n=5 per group). A cohort (n=5) of control mice were similarly injected with Yttrium-86 oxine only. Images were acquired on a small animal PET (SAPET) (Mosaic, Philips Medical Systems) at 2, 24 and 45 hours post administration. Mice were then euthanized and popliteal, axillary and inguinal lymph nodes (LN) harvested. LN were processed into single cell suspension, stained with anti-human HLA-DR and CD11c and analysed by flow cytometry. SAPET images were graded: 0 – no signal, 1 – marginal, 2 – definite nodal signal, 3 – strong signal. DC detection by FACS was graded: 0 – no detection, 1 – <0.5% DC, 2 – 0.5.⋄1.5% DC, 3 – >1.5% DC of all viable cellular events. Results: Pre-injection analysis of DC showed expression of HLA-DR, HLA-ABC, CD11c, CD80 and CD86, low levels of CD83, CCR5 and CCR7 along with down regulation of CD14. Matured DC populations showed increased levels of CD83 and CD86. Similar phenotypic expression on the DC populations were observed prior to cryopreservation and upon thawing. Mean DC radiolabelling efficiency of 72% (54% – 88%). There was a minor decrease in cell numbers and viability after labelling most likely due to oxine related toxicity. There were no substantial differences in tracking between cell types. In 28 of 43 nodes assessed, FACS and SAPET results were congruent (27 FACS and SAPET positive and 1 FACS and SAPET negative). Of the 15 discrepant samples, 13 were SAPET positive and FACS negative, while 2 were FACS positive and PET negative. Average FACS and SAPET grades at 45 hours were higher for popliteal nodes than axillary nodes. No false positive nodal accumulation was visualised at 45 hours in control mice. Conclusion: This novel PET technique provides a robust, reproducible method for quantification of in vivo functional DC tracking to LN. Detection of DC migration using this novel PET agent is a more reliable technique than biopsy and FACS analysis, which has an inherent sampling error.

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