Which of the following events occur first in the differentiation sequence of human B cells in the bone marrow?
The first event that occurs in the pre-B cell (progenitor) is the gene rearrangement of the heavy chain. The D gene and J gene recombination event occurs first, followed by V recombination with the D-J region. The cytoplasmic mu chains are the result of immunoglobulin heavy chain rearrangement, the production of the messenger RNA from this rearrangement, and the ribosomal synthesis of the protein mu chain. This is the second event that occurs in the B-cell maturational sequence. Light chain rearrangement occurs when recombination events occur with the V gene and J gene from the light chain germline. After this recombination has occurred, and the messenger RNA for this germ line has produced the light chain protein, the light chains and heavy chains form. The complete IgM molecule and IgD molecules are present on the surface of only the mature B cells. This event is the last event to occur during the differentiation and development of B cells in the bone marrow. Ref: Brooks G.F., Carroll K.C., Butel J.S., Morse S.A., Mietzneron T.A. (2010). Chapter 8. Immunology. In G.F. Brooks, K.C. Carroll, J.S. Butel, S.A. Morse, T.A. Mietzneron (Eds), Jawetz, Melnick, & Adelberg's Medical Microbiology, 25e.
Cytoplasmic mu chains present in the B cell
Immunoglobulin heavy chain rearrangement
Immunoglobulin light chain rearrangement
Surface IgD and IgM present on the B cell