Autologous dendritic cells prolong allograft survival through Tmem176b-dependent antigen cross-presentation

The administration of autologous (recipient-derived) tolerogenic dendritic cells (ATDCs) is under clinical evaluation. However, the molecular mechanisms by which these cells prolong graft survival in a donor-specific manner is unknown. Here, we tested mouse ATDCs for their therapeutic potential in a skin transplantation model. ATDC injection in combination with anti-CD3 treatment induced the accumulation of CD8(+) CD11c(+) T cells and significantly prolonged allograft survival. TMEM176B is an intracellular protein expressed in ATDCs and initially identified in allograft tolerance. We show that Tmem176b(-/-) ATDCs completely failed to trigger both phenomena but recovered their effect when loaded with donor peptides before injection. These results strongly suggested that ATDCs require TMEM176B to cross-present antigens in a tolerogenic fashion. In agreement with this, Tmem176b(-/-) ATDCs specifically failed to cross-present male antigens or ovalbumin to CD8(+) T cells. Finally, we observed that a Tmem176b-dependent cation current controls phagosomal pH, a critical parameter in cross-presentation. Thus, ATDCs require TMEM176B to cross-present donor antigens to induce donor-specific CD8(+) CD11c(+) T cells with regulatory properties and prolong graft survival.

The US gun stock: results from the 2004 national firearms survey

OBJECTIVES

To examine the size and composition of the privately held firearm stock in the US; and to describe demographic patterns of firearm ownership and motivations for ownership.

DESIGN, SETTING AND PARTICIPANTS

A nationally representative household telephone survey of 2770 adults aged>or=18 years living in the US, conducted in the spring of 2004.

MAIN OUTCOME MEASURE

Responses to questions regarding firearm ownership, the number and types of guns owned, and motivations for ownership.

RESULTS

38% of households and 26% of individuals reported owning at least one firearm. This corresponds to 42 million US households with firearms, and 57 million adult gun owners. 64% of gun owners or 16% of American adults reported owning at least one handgun. Long guns represent 60% of the privately held gun stock. Almost half (48%) of all individual gun owners reported owning>or=4 firearms. Men more often reported firearm ownership, with 45% stating that they personally owned at least one firearm, compared with 11% for women.

CONCLUSIONS

The US population continues to contain at least one firearm for every adult, and ownership is becoming increasingly concentrated. Long guns are the most prevalent type of gun in the US but handgun ownership is widespread. Ownership demographic patterns support findings of previous studies.

The association between changes in household firearm ownership and rates of suicide in the United States, 1981-2002

OBJECTIVE

To explore whether recent declines in household firearm prevalence in the United States were associated with changes in rates of suicide for men, women, and children.

METHODS

This time series study compares changes in suicide rates to changes in household firearm prevalence, 1981-2002. Multivariate analyses adjust for age, unemployment, per capita alcohol consumption, and poverty. Regional fixed effects controlled for cross sectional, time invariant differences among the four census regions. Standard errors of parameter estimates are adjusted to account for serial autocorrelation of observations over time.

RESULTS

Over the 22 year study period household firearm ownership rates declined across all four regions. In multivariate analyses, each 10% decline in household firearm ownership was associated with significant declines in rates of firearm suicide, 4.2% (95% CI 2.3% to 6.1%) and overall suicide, 2.5% (95% CI 1.4% to 3.6%). Changes in non-firearm suicide were not associated with changes in firearm ownership. The magnitude of the association between changes in household firearm ownership and changes in rates of firearm and overall suicide was greatest for children: for each 10% decline in the percentage of households with firearms and children, the rate of firearm suicide among children 0-19 years of age dropped 8.3% (95% CI 6.1% to 10.5%) and the rate of overall suicide dropped 4.1% (2.3% to 5.9%).

CONCLUSION

Changes in household firearm ownership over time are associated with significant changes in rates of suicide for men, women, and children. These findings suggest that reducing availability to firearms in the home may save lives, especially among youth.