Final answer:
The incorrect pair that does not associate during B-cell development is option 'b,' the surrogate light chain: δ heavy chain. The surrogate light chain and the μ heavy chain form the early B-cell receptor, which is a critical step before the development of functional B cells.
Step-by-step explanation:
The student's question pertains to components that interact during B-cell development. In this process, different molecules associate with each other to form precursor B cell receptors and promote maturation into fully functional B cells capable of producing antibodies. Each of the pairs mentioned in the question plays a specific role in B cell development, except for the surrogate light chain associating with the δ heavy chain (option 'b'). The surrogate light chain usually consists of two proteins, VpreB and λ5, which pair with the μ heavy chain in the early B-cell receptor before the actual light chains are produced through genetic rearrangement and express themselves. These interactions are crucial for the B cells to undergo proper development and maturation.
For example, IL-7 binding to the IL-7 receptor on late pro-B cells (a) is an important interaction that signals B cell growth and development. The VpreB and λ5 components of the surrogate light chain (c) also play essential roles in early B-cell receptor formation. Furthermore, the pre-B-cell receptor complex formation (e) includes correct associates being the pre-BCR itself and the signaling molecules Igα and Igβ which are needed for B cell development and checkpoint transitions. Whereas SCF (stem cell factor) binding to the c-Kit receptor (d) is crucial for hematopoietic stem cells and early B cell progenitors.