Palladium-Induced Temporal Internalization of MHC Class I Contributes to T Cell-Mediated Antigenicity

Palladium (Pd) is a widely used metal and extremely important biomaterial for the reconstruction of occlusions during dental restorations. However, metallic biomaterials can cause serious allergic reactions, such as Pd-related oral mucositis seen in dentistry. Metal allergy is categorized as a type IV allergy and we demonstrated that CD8 T cells play an important role in Pd allergy previously. As TCR of CD8 T cells recognizes MHC class I/peptide complex, the antigen specificity to this complex seems to be generated during Pd allergy. However, it remains unknown if Pd affects the MHC class I/peptide complex. In this study, we investigated the behavior of the MHC class I/peptide complex in response to Pd treatment. We found that PdCl2 treatment altered peptide presentation on MHC class I and that co-culture with Pd-treated DC2.4 cells induced activation of Pd-responsive TCR-expressing T cell line. Furthermore, PdCl2 treatment induced temporal MHC class I internalization and inhibition of membrane movement suppressed Pd-induced T cell-mediated antigenicity. These data suggest that Pd-induced MHC class I internalization is critical for generation of antigenicity through a mechanism including differential peptide loading on MHC class I, which results in Pd allergy.

Exopolysaccharide Produced by Lactobacillus paracasei IJH-SONE68 Prevents and Improves the Picryl Chloride-Induced Contact Dermatitis

Allergic disease is one of the most important and common health problems worldwide. We have previously demonstrated that a fig leaf-derived lactic acid bacterium Lactobacillus (Lb.) paracasei IJH-SONE68 produces a novel exopolysaccharide (EPS). Furthermore, we have shown that the EPS inhibits the catalytic activity of hyaluronidase (EC 3.2.1.36) promoting inflammatory reactions. To evaluate the anti-allergy and anti-inflammatory effects of the EPS, in the present study, we employed the picryl-chloride-induced delayed-type (type IV) allergy model mice, which is used to evaluate the contact dermatitis. Oral administration of the EPS was observed to reduce the ear swelling in the model mice. We also observed that the overexpression of ear interleukin-4 (T helper (Th) 2 cytokine) mRNA and the increase in serum immunoglobulin E (IgE) are repressed. However, the expression of interferon-γ (Th1 cytokine) was not accelerated in all of the allergen-challenged model mice. The improvement may be responsible for the Th2 downregulation rather than the Th1 upregulation. In addition, the symptom of immediate-type (type I) allergy model mice was improved by oral administration of the IJH-SONE68 cell (data not shown). We can conclude that the IJH-SONE68-derived EPS is useful to improve the type I and IV allergies including atopic dermatitis.

“NITROSAMINE SAFE” THIURAM DISULFIDE

ABSTRACT An investigation into the technological performance of a new nitrosamine safe thiuram disulfide, tetraisononylthiuramdisulfide (TINTD), in natural rubber was undertaken. Initially, TINTD was synthesized from di(3,5,5-trimethylhexyl)amine. It was then demonstrated to function as a sulfur donor, a primary accelerator, and as a secondary accelerator when combined with sulfenamides. These investigations found that the long-branched alkyl chain on the nitrogen of TINTD and of its vulcanization breakdown product zinc diisononyldithiocarbamate (ZDNC) makes both chemical species very soluble in the elastomer. This high solubility of TINTD and ZDNC in the rubber makes TINTD highly attractive for use in soluble efficient vulcanization systems. In addition, the nature of the long-branched alkyl chain means that the formation of carcinogenic N-nitrosamine is difficult, and if formed, it is toxicologically much less hazardous in terms of both acute toxicity and metabolic activity. Thus, concerns of accelerator toxicity, irritant dermatitis from thiuram and dithiocarbamate, and type IV allergy may be reduced or totally eliminated. The curing efficiency of various thiuram disulfides was also investigated as a function of alkyl chain length and the degree of chain branching. The cure performance was found to be determined by both chain length and chain branching.

Allergic Reaction to Polyether Ether Ketone Following Cross-Reactivity to Epoxy Resin

Polyether ether ketone (PEEK) is a thermoplastic polymer frequently used in engineering but also in medical devices. Only 1 case of allergic reaction to PEEK used as an implanted medical device has been reported so far; however, the route of sensitization remained unclear. Here we report on a 62-year-old male patient with a preknown, severe type IV allergy to epoxy resin. He reported strong pain in his shoulder after implantation of a PEEK-containing device after a rotator cuff injury. For testing, the device was implanted in a small pouch subcutaneously on the abdomen. The patient reported massive pain starting 8 hours after the implantation, strictly limited to the procedural area and showing perifocal erythema. A possible explanation of the sensitization mode is the source material for PEEK and epoxy resin, as both are mainly based on bisphenols. An allergic reaction to PEEK with preknown epoxy resin sensitization has not been reported so far. As epoxy resins are a frequent cause of occupational contact dermatitis and PEEK is widely used for medical and nonmedical devices, we believe that this is of great clinical relevance.