Immunoglobulin isotype class switching is determined by -: (A) Constant region of light chain, (B) Constant region of heavy chain, (C) Variable region of light chain, (D) Variable region of heavy chain
Answer is B. Antibody genes also re-organize in a process called class switching that changes the one type of heavy chain Fc fragment to another, creating a different isotype of the antibody that retains the antigen specific variable region Ref: Ananthanarayan & Parkers textbook of microbiology 9th edition pg: 96