Both B and T Cells express surface antigen receptors, the B Cell Receptor (BCR) and T Cell Receptor (TCR), respectively. During development each of these kinds of immature lymphocytes will express early versions of these receptors on their surface (Pre-BCR and Pre-TCR).
What is the purpose of expressing these receptors long before they will ever come into contact with antigens?
answer quickly – the first correct (and complete) answer gets 3 pts extra credit on the upcoming exam!
DownHouseSoftware 
Ivy Poetter
April 30, 2015 at 10:35 am
They express these early to see if they bind to self.
Laura Pryor
May 2, 2015 at 8:10 pm
Because antigen receptors are randomized and may be unstable. This step ensures that the receptor is stably expressed. 🙂