Cutting Edge: CD28 Controls Dominant Regulatory T Cell Activity during Active Immunization

Cutting edge: CD28 controls peripheral homeostasis of CD4+CD25+ regulatory T cells.

CD28/B7 blockade leads to exacerbated autoimmune disease in the nonobese diabetic mouse strain as a result of a marked reduction in the number of CD4(+)CD25(+) regulatory T cells (Tregs). Herein, we demonstrate that CD28 controls both thymic development and peripheral homeostasis of Tregs. CD28 maintains a stable pool of peripheral Tregs by both supporting their survival and promoting their sel...

Cutting edge: CD28 and c-Rel-dependent pathways initiate regulatory T cell development.

Regulatory T cell (Treg) development proceeds via a two-step process in which naive CD4(+) thymocytes are first converted into CD4(+)CD25(+)CD122(+)GITR(+)Foxp3(-) Treg progenitors, followed by a second step in which IL-2 converts these Treg progenitors into CD4(+)Foxp3(+) Tregs. The costimulatory molecule CD28 is required for efficient Treg development. However, the stage at which CD28 affects...

Cutting Edge: Responder T cells regulate human DR+ effector regulatory T cell activity via granzyme B.

MHC class II expression identifies an effector subset of human CD4(+)CD25(high)FoxP3(high) natural regulatory T cells (DR(+) Tregs) that induces more rapid suppression and exhibits higher FoxP3 expression than the remaining Treg population. Although Tregs are known to be highly sensitive to apoptosis, in this study we demonstrate that this sensitivity is primarily a feature of DR(+) Tregs. Gran...

Cutting edge: Intrathymic differentiation of adaptive Foxp3+ regulatory T cells upon peripheral proinflammatory immunization.

Thymocytes differentiate into CD4(+) Foxp3(+) regulatory T cells (T(R)) upon interaction between their TCR and peptide-MHC II complexes locally expressed in the thymus. Conversion of naive CD4(+) T cells into T(R) can additionally take place in the periphery under noninflammatory conditions of Ag encounter. In this study, making use of TCR transgenic models naturally devoid of Foxp3(+) cells, w...

Cutting Edge: Stimulation of CD28 with B7