A fundamental difference in the capacity to induce proliferation of naive T cells between CD28 and other co-stimulatory molecules

Genetics Institute Inc., Cambridge, USAT cell activation requires two signals: a signal from the TCR and a co-stimulatory signal pro-vided by antigen-presenting cells (APC). In addition to CD28, multiple molecules on the T cellhave been described to deliver co-stimulatory signals. Here, we investigated whether thereexist quantitative or qualitative differences in the co-stimulatory capacity between CD28 andother molecules. Anti-CD28 monoclonal antibody (mAb) and mAb against CD5, CD9, CD2,CD44 or CD11a all induced activation of naive T cells in the absence of APC when co-immobilized with a submitogenic dose of anti-CD3 mAb. [