2.a B cell becomes immunocompetent following productive rearrangement of variable region heavy-chain and light-chain gene segments in germ-line DNA, following binding of TH cytokines to their receptors on the B cell for Humoral Immunity (HI), following productive rearrangement of variable region heavy-chain gene segments in germ-line DNA, and following class switching.
16. The Ig promoter that confers B cell specificity is E2A, TATA box, GC box, and Oct-2.