Sustained delayed-type hypersensitivity reaction after in vivo priming but successful induction of unresponsiveness after adoptive transfer of CD4+ effector T cells

Facilitated Peptide Transport via the Mucosal Epithelium: Impact on Tolerance Induction

A hallmark of autoimmunity is the breakdown of tolerance and generation of effector responses against self-antigens. Re-establishment of tolerance in autoimmune disorders was always the most desired treatment option; however, despite many efforts, clinical trials have been largely unsuccessful. This also applies to the generation of oral tolerance, which seems to be a default response type of the mucosa-associated lymphoid tissues to harmless antigens. In this study, we report improved efficacy of oral tolerance induction by coupling antigen with the newly identified mucosal carrier peptide 13C. Antigen coupled to 13C is efficiently taken up in the gastrointestinal tract and could be visualized in cells of the lamina propria. Oral, rectal, or nasal treatment effectively induced the proliferation of antigen-specific T cells with some increase in the frequency of regulatory T cells. In a model of delayed-type hypersensitivity, especially intrarectal tolerization treatment resulted in reduced footpad swelling, demonstrating a moderate tolerogenic effect of mucosal treatment with 13C coupled antigen. Coupling of antigens to a transmucosal carrier, therefore, is a promising tool to improve the efficacy of vaccination via mucosal surfaces.

Wound drainage after metal-on-metal hip arthroplasty secondary to presumed delayed hypersensitivity reaction

An emerging concern with metal-on-metal total hip arthroplasty is metal-induced hypersensitivity. Currently, this is a diagnosis of exclusion in patients with groin pain after metal-on-metal total hip arthroplasty. We describe a patient presenting nearly a year after arthroplasty with incisional drainage. Infection was presumed; but preoperative studies were nondefinitive, and the wound was explored. The operative cultures were negative; the histology revealed lymphocytic vasculitis. The patient recovered uneventfully after exchange to a metal polyethylene bearing couple. We believe that metal-induced hypersensitivity should be considered with draining wounds with this bearing couple if infection cannot be proven.

T cells as pioneers: antigen-specific T cells condition inflamed sites for high-rate antigen-non-specific effector cell recruitment

Cellular infiltration is a classic hallmark of inflammation. Whereas the role of T cells in many types of inflammation is well established, the specific impact of antigen recognition on their migration into the site and on the accumulation of other effector cells are still matters of debate. Using a model of an inflammatory effector phase driven by T-cell receptor (TCR) transgenic T cells, we found (i) that antigen-specific T cells play a crucial role as 'pioneer cells' that condition the tissue for enhanced recruitment of further T effector cells and other leucocytes, and (ii) that the infiltration of T cells is not dependent on antigen specificity. We demonstrate that a small number of antigen-specific T cells suffice to initiate a cascade of cellular immigration into the antigen-loaded site. Although antigen drives this process, accumulation of T cells in the first few days of inflammation was not dependent on T-cell reactivity to the antigen. Both transgenic and wild-type T effector cells showed enhanced immigration into the site of antigen challenge after the initial arrival and activation of antigen-specific pioneer cells. This suggests that bystander accumulation of non-specific effector/memory T cells is a general feature in inflammation. Furthermore, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma were identified as mediators that contribute to conditioning of the inflammatory site for high-rate accumulation of T effector cells in this T-cell-driven model.