Which of the Following Statements About Ig Isotype Switching Is

Multiple Choice

Which of the following statements about Ig isotype switching is NOT true?

A) Interleukin-4 promotes switching to the IgE isotype by increasing germline transcription of the CϬ exon.
B) Isotype switching involves recombination of a V(D) J complex with downstream C region genes and the deletion of intervening DNA including other C region genes.
C) Activation-induced deaminase (AID) is required for switch recombination.
D) The enzymes that mediate isotype switching recognize conserved heptamer and nonamer DNA sequences adjacent to the constant region exons.
E) The same recombined V(D) J gene complex is used to encode the antigen-binding region of the antibodies produced by a B cell before and after isotype switching.