Final answer:
If the VDJh rearrangement is non-productive in B cell development, the B cell can try on the second allele; if both fail, the cell undergoes apoptosis. Successful rearrangements lead to a diverse antibody repertoire by splicing various V, D, and J segments. Non-productive rearrangements impede B cell maturation and can lead to immunodeficiency disorders.
Step-by-step explanation:
When there is a non-productive VDJh rearrangement in B cell development, meaning the rearrangement does not lead to the expression of a functional pre-B Cell Receptor (pre-BCR), the cell usually gets a second chance. B lymphocytes have two alleles for the heavy chain locus, giving them two opportunities to generate a productive rearrangement. If the first rearrangement is non-productive, the B cell can attempt rearrangement on the second allele. However, if both attempts fail to produce a functional pre-BCR, the cell is typically eliminated by a process known as apoptosis. This mechanism ensures that only B cells with the potential to produce functional receptors are selected for further maturation and eventual participation in the immune response.During the VDJ recombination process, DNA recombinase splices different V (Variable), D (Diversity), and J (Joining) segments together to create the variable region of the BCR heavy chain, and V and J segments for the light chain. This diversity allows for the generation of BCRs with unique antigen-binding sites, providing the foundation for the vast diversity of the antibody repertoire. Without a functional pre-BCR, the B cell will not proceed to the next stage of development, which could lead to conditions like X-linked agammaglobulinemia (XLA), where the maturation of B cells is halted due to the absence of Bruton tyrosine kinase (Btk), and patients become susceptible to recurrent infections.