Which One of the Following Statements About the Molecules B7-1 $\gamma$

Multiple Choice

Which one of the following statements about the molecules B7-1 and B7-2 is NOT true?

A) B7-1 and B7-2 expression on antigen-presenting cells (APCs) is upregulated by the presence of "danger" signals,such as lipopolysaccharide,as well as cytokines,such as interferon (IFN) - $\gamma$
B) B7-1 and B7-2 are expressed at low levels on some resting APCs.
C) Induction of B7-1 usually occurs before the induction of B7-2 in an immune response.
D) B7-1 and B7-2 bind to CD28 on T cells and provide "second signals" for naive T cell activation.
E) Activated helper T cells can induce expression of B7-1 and B7-2 on APCs via CD40L binding to CD40.