Simplified prognostic indicators for AIDS-related lymphoma

cells produce and release granzyme B similarly to CD8 T cells, an activity not found in CD4 CD25 T cells. The authors further demonstrate that Bcell apoptosis mediated by CD4 CD25 T cells can be antigen dependent. CD4 CD25 T cells from mice bearing a transgenic TCR that recognizes an ovalbumin peptide were used for these experiments. Proliferating B cells were divided into 2 separate groups, one pulsed with ovalbumin and one unpulsed. Ovalbumin-specific CD4 CD25 T cells were dramatically more efficient at killing antigen-pulsed B cells, demonstrating that this Treg activity is indeed antigen dependent. Thus, an entirely new mechanism of Treg activity has been discovered. B-cell proliferation is controlled in a completely different manner from T-cell proliferation. This mechanism involves direct, antigen-selective induction of B-cell apoptosis. These findings are an important advance in our knowledge of Treg function. ■