Hapten application to the skin induces an inflammatory program directing hapten-primed effector CD8 T cell interaction with hapten-presenting endothelial cells (60.6)

Contact hypersensitivity (CHS) is a CD8 T cell-mediated response to hapten sensitization and challenge of the skin. Effector CD8 T cell recruitment into the skin parenchyma to elicit CHS to hapten challenge requires prior CXCL1-directed neutrophil infiltration within 3-6 h after challenge and is dependent on IFN-γ and IL-17 produced by the hapten-primed CD8 T cells. Mechanisms directing CD8 T cell localization and activation in the challenge site to induce CXCL1 production in response to 2, 4-dinitrofluorobenzene were investigated. Both TNFα and IL-17, but not IFN-γ, mRNA was detectable within 1 h of hapten challenge of sensitized mice and increased thereafter. Expression of ICAM-1 was observed by 1 h after challenge of sensitized and non-sensitized mice and was dependent on TNFα. The induction of IL-17, IFN-γ and CXCL1 in the challenge site was not observed when ICAM-1 was absent or neutralized by specific antibody. During the elicitation of CHS, endothelial cells (EC) expressed ICAM-1 and produced CXCL1. EC isolated from challenged skin of naïve and sensitized mice had acquired the hapten and the ability to activate hapten-primed CD8 T cell cytokine production. These results indicate that hapten application to the skin of sensitized animals initiates an inflammatory response promoting hapten-primed CD8 T cell localization to the challenge site through TNFα induced ICAM-1 expression and CD8 T cell activation to produce IFN-γ and IL-17 through EC presentation of hapten.

Hapten application to the skin induces an inflammatory program directing hapten-primed effector CD8 T cell interaction with hapten-presenting endothelial cells

Contact hypersensitivity is a CD8 T cell-mediated response to hapten sensitization and challenge of the skin. Effector CD8 T cell recruitment into the skin parenchyma to elicit the response to hapten challenge requires prior CXCL1/KC-directed neutrophil infiltration within 3-6 h after challenge and is dependent on IFN-γ and IL-17 produced by the hapten-primed CD8 T cells. Mechanisms directing hapten-primed CD8 T cell localization and activation in the Ag challenge site to induce this early CXCL1 production in response to 2,4-dinitrofluorobenzene were investigated. Both TNF-α and IL-17, but not IFN-γ, mRNA was detectable within 1 h of hapten challenge of sensitized mice and increased thereafter. Expression of ICAM-1 was observed by 1 h after challenge of sensitized and nonsensitized mice and was dependent on TNF-α. The induction of IL-17, IFN-γ, and CXCL1 in the challenge site was not observed when ICAM-1 was absent or neutralized by specific Ab. During the elicitation of the contact hypersensitivity response, endothelial cells expressed ICAM-1 and produced CXCL1 suggesting this as the site of CD8 T cell localization and activation. Endothelial cells isolated from challenged skin of naive and sensitized mice had acquired the hapten and the ability to activate hapten-primed CD8 T cell cytokine production. These results indicate that hapten application to the skin of sensitized animals initiates an inflammatory response promoting hapten-primed CD8 T cell localization to the challenge site through TNF-α-induced ICAM-1 expression and CD8 T cell activation to produce IFN-γ and IL-17 through endothelial cell presentation of hapten.

A novel method for subarachnoid hemorrhage to induce vasospasm in mice

Mouse models take advantage of genetic manipulations that can be achieved in this species. There are currently two accepted mouse models of subarachnoid hemorrhage (SAH) and cerebral vasospasm (CVs). Both are technically demanding and labor intensive. In this study, we report a reproducible and technically feasible method to induce SAH, and subsequently CVs, in mice. We tested this model in multiple strains of mice that are commonly used for genetic manipulation.

METHODS

SAH was induced in C57BL/6NCr, FVB, 129S1, BalbC and SJL mice, weighing 28-32 g, by an intracisternal vessel transection technique. Animals were perfused with India ink at 24h postprocedure and vessel diameters were quantified. Brain slices were obtained for hematoxylin-eosin staining (H&E) to look for vascular changes consistent with CVs.

RESULTS

There was no mortality during or after the procedure. Four of the five mouse strains showed significant CVs at 24 h postprocedure characterized by decreased vessel diameter of the middle cerebral artery close to the Circle of Willis. Histologically, the vessel wall displayed significant corrugation and thickening, consistent with CVs.

CONCLUSION

A novel mouse model to induce SAH is described and tested in several mouse strains. Four of the five strains used in this study developed CVs after the induction of SAH. The procedure is brief, straightforward, reproducible with low mortality, and applicable to commonly used background strains for genetically engineered mice.

Pretransplant cellular alloimmunity as assessed by a panel of reactive T cells assay correlates with acute renal graft rejection

BACKGROUND

The panel reactive antibody test (PRA) is an established method for assessing posttransplant risk of immune-mediated graft injury. The panel of reactive T cell assay (PRT) in which transplant candidates' peripheral blood mononuclear cells are tested for reactivity to a panel of allogenic stimulator cells by the IFN-gamma enzyme-linked immunosorbent spot assay analogously assesses the strength of the pretransplant effector-memory alloreactive T cell repertoire.

METHODS

PRT assays were performed in 30 kidney transplant candidates and results were correlated with acute rejection (AR). A positive PRT assay was defined as a response to at least 75% of the stimulators tested.

RESULTS

A positive pretransplant PRT test was observed in 11 of 30 (37%) patients, and AR within 1 year posttransplantation was seen in 7 of 30 (23%) subjects. Six of the seven (86%) patients with AR were PRT-positive (P=0.01) whereas only one of seven (14%) patients with a PRA greater than 15% had AR. The mean pretransplant PRT percentage was 40% for patients with no AR versus 81% for patients with AR (P=0.01). Estimated glomerular filtration rate (mL/min/1.73 m2) showed a trend towards a lower value in PRT-positive (48+/-15) versus PRT-negative (55+/-13) individuals.

CONCLUSIONS

The data suggest that pretransplant PRT screening can identify patients at risk for posttransplant cellular immune mediated graft injury despite the absence of humoral allosensitization. Once confirmed by larger prospective trials, PRT screening could be used to guide clinical decision-making with regard to choosing donor organs and individualizing immunosuppression regimens.