<prompt> Cell surface molecules involved in peripheral toleranceB7 and CD28CD40 and CD40LCD 34 and CD51B7 and CD3  <response>: Ref Robbins 7e p225 , Harrison 16e p1907, Robbins 9e p213 B7 is a type of peripheral membrane protein found on activated antigen presenting cells that, when paired with either a CD28 or CD152 surface protein on a T cell, can produce a costimulatory signal 