OBJECTIVEThe International Association of the Diabetes and Pregnancy Study Groups (IADPSG) recently recommended new criteria for diagnosing gestational diabetes mellitus (GDM). This study was undertaken to determine whether adopting the IADPSG criteria would be cost-effective, compared with the current standard of care.RESEARCH DESIGN AND METHODSWe developed a decision analysis model comparing the cost-utility of three strategies to identify GDM: 1) no screening, 2) current screening practice (1-h 50-g glucose challenge test between 24 and 28 weeks followed by 3-h 100-g glucose tolerance test when indicated), or 3) screening practice proposed by the IADPSG. Assumptions included that 1) women diagnosed with GDM received additional prenatal monitoring, mitigating the risks of preeclampsia, shoulder dystocia, and birth injury; and 2) GDM women had opportunity for intensive postdelivery counseling and behavior modification to reduce future diabetes risks. The primary outcome measure was the incremental cost-effectiveness ratio (ICER).RESULTSOur model demonstrates that the IADPSG recommendations are cost-effective only when postdelivery care reduces diabetes incidence. For every 100,000 women screened, 6,178 quality-adjusted life-years (QALYs) are gained, at a cost of $125,633,826. The ICER for the IADPSG strategy compared with the current standard was $20,336 per QALY gained. When postdelivery care was not accomplished, the IADPSG strategy was no longer cost-effective. These results were robust in sensitivity analyses.CONCLUSIONSThe IADPSG recommendation for glucose screening in pregnancy is cost-effective. The model is most sensitive to the likelihood of preventing future diabetes in patients identified with GDM using postdelivery counseling and intervention.

Tertiary lymphoid tissues are lymph node-like cell aggregates that arise at sites of chronic inflammation. They have been observed in transplanted organs undergoing chronic rejection, but it is not known whether they contribute to the rejection process by supporting local activation of naïve lymphocytes. To answer this question, we established a murine transplantation model in which the donor skin contains tertiary lymphoid tissues due to transgenic expression of lymphotoxin-a (RIP-LT a ), whereas the recipient lacks all secondary lymphoid organs and does not mount primary alloimmune responses. We demonstrate in this model that RIP-LT a allografts that harbor tertiary lymphoid tissues are rejected, while wild-type allografts that lack tertiary lymphoid tissues are accepted. Wildtype allografts transplanted at the same time as RIP-LT a skin or 60 days later were also rejected, suggesting that tertiary lymphoid tissues, similar to secondary lymphoid organs, generate both effector and memory immune responses. Consistent with this observation, naive T cells transferred to RIP-LTa skin allograft but not syngeneic graft recipients proliferated and differentiated into effector and memory T cells. These findings provide direct evidence that tertiary lymphoid structures perpetuate the rejection process by supporting naïve T-cell activation.

Foreign Ags that enter immunologically privileged sites such as the eye, brain, and testis persist for an extended period of time, whereas the same Ags are rapidly eliminated at conventional sites. Immune privilege, therefore, provides unwanted refuge for pathogens and tumor cells but is beneficial for the survival of allogeneic grafts. In this study, we asked whether memory T cells can eliminate foreign Ags deposited at an immunologically privileged site by studying CD8 memory T cell-mediated rejection of pancreatic islet allografts placed either in the testis (a privileged organ) or under the kidney capsule (a nonprivileged site) of diabetic mice. We found that CD8 memory T cells reject intratesticular grafts at a significantly slower rate than the rejection of intrarenal grafts. Delayed graft rejection in the testis was not due to reduced homing or proliferation of memory T cells but due to their increased apoptosis at that site. Apoptosis was mediated by the combined actions of two TNFR family members that are up-regulated on activated memory T cells, Fas, and CD30. Therefore, memory T cells survey immunologically privileged tissues but are subject to the immunosuppressive mechanisms present at these sites.

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