Synopsis of Lestes from Brazil with description of Lestes demarcoi sp. nov. (Zygoptera: Lestidae).

The Brazilian fauna of Lestidae contains two genera (Archilestes Selys, 1862 and Lestes Leach in Brewster, 1815) with 14 species, many of which are poorly defined and/or known only by primary literature. To improve the knowledge of the Brazilian species of the genus Lestes we examined 97 specimens pertaining to 11 of the 13 described species. Additionally, a new species is described here in honor to Prof. Dr. Paulo De Marco Júnior: Lestes demarcoi (Holotype and Allotype: Brazil: Amazonas, Manaus, Reserva Adolpho Ducke, Acará trail, 02º55'46" S 59º58'22" W, 62 m, 13.iv.2009, collected in tandem, U.G. Neiss leg. and deposited in FAAL). Diagnostic illustrations of all species are provided. Color photographs of live individuals of Lestes dichrostigma Calvert, 1909, Lestes forficula Rambur, 1842 and Lestes paulistus Calvert, 1909 are also presented.

Non-coordinate synthesis of MHC class II proteins and invariant chains by epidermal Langerhans cells derived from short-term in vitro culture.

Epidermal cells (EC) prepared from Lewis rat skin contained 2-3% class II+, LCA+ Langerhans cells (LC). LC enriched from freshly isolated EC suspensions proved highly effective accessory cells when presenting the nominal antigen OVA to an RT1.Bl-restricted ovalbumin (OVA)-specific rat T cell clone. Short-term preculture of the EC resulted in diminished OVA presenting capacity of the LC. Flow cytometry (FCM) analysis of class II and gamma chain expression revealed an up-regulation of class II on the LC's cell surface, consistent with earlier findings in mouse and human. However, while the presence of gamma chains in mouse LC was reported to decline to negligible levels during culture we observed substantial gamma surface expression on 3 day cultured rat LC, accompanied by increasing quantities of gamma inside the cells as revealed by FCM analysis on permeabilized cells. Biosynthetic labeling of panning-enriched LC from fresh and cultured EC confirmed and extended the immunocytological analysis. In contrast to the synthesis of class II proteins, that declined during culture to background levels, gamma chain synthesis was strongly augmented after 1 day in culture and remained at prominent levels throughout the culture period. In LC pulse labeled for 4 h and subjected to a 3 day chase period prominent quantities of labeled class II complexes were detectable with the majority of the dimers exhibiting the compact (C)-type folding form. On the basis of our findings a novel function of the invariant gamma chain is suggested to be effective in LC.

Contact allergens modulate the expression of MHC class II molecules on murine epidermal Langerhans cells by endocytotic mechanisms.

MHC class II molecules play an important role during the sensitization phase of allergic contact dermatitis. To study the influence of contact allergens on the expression of these molecules by murine epidermal Langerhans cells (LC), we performed a flow-cytofluorometric analysis of the Ia-antigen expression after in vivo application of contact allergens. A distinct decrease in the Ia-antigen expression of the entire LC population was noticed 3 h after in vivo application of the contact allergen 2,4-dinitrofluorobenzene (DNFB). This decrease was transient and balanced 24 h after in vivo application of DNFB. A downregulation was also detectable after in vivo application of the contact allergens 1-chloro-2,4-dinitrobenzene (DNCB), oxazolone, K2Cr2O7, 2,4,6-trinitrochlorobenzene (TNCB), and toxic concentrations of the irritant compound sodium dodecyl sulfate (SDS). In vitro studies showed that freshly prepared as well as 3-d cultured LC downregulated their Ia-antigen expression in the presence of DNFB, which was used as a model compound. This decrease was not inhibited by the MHC class II molecule transport-inhibitor brefeldin A nor by the ionophore monensin. The inhibition of receptor-mediated endocytosis with hypertonic media (0.45 M sucrose) abolished the DNFB-mediated downregulation of Ia-antigen expression. An accelerated clearance of cell-surface-expressed antibody-labeled IA molecules was detectable in the presence of DNFB. Internalization studies carried out with peroxidase-labeled anti-IA-antibody complexes showed remarkable alterations in the intracellular distribution of endocytosed material under the influence of subtoxic concentrations of DNFB, DNCB, K2Cr2O7, and TNCB. The irritant substance sodium dodecyl sulfate (SDS) influenced the intracellular distribution pattern of internalized material only when used in toxic concentrations. An augmented participation of MHC class II molecules in endocytotic processes is mediated by reactive substances like contact allergens and might contribute to the processing and presentation of these compounds.