Which process introduces the greatest diversity in immune receptors?

The process that introduces the greatest diversity in immune receptors is junctional diversity. This mechanism occurs during the rearrangement of immunoglobulin (Ig) genes and T-cell receptor (TCR) genes, where additional genetic material is added or removed at the junctions where gene segments are combined.

When lymphocyte precursors undergo V(D)J recombination, which is responsible for the generation of diverse antigen receptors, the enzymes involved can add non-template nucleotides at the junctions between gene segments. This variability significantly enhances the diversity of the immune receptors, contributing to the ability of the immune system to recognize a vast array of antigens.

Other processes such as class switching, somatic hypermutation, and gene rearrangement also contribute to immune receptor diversity. Class switching allows B cells to produce different classes of antibodies (like IgM to IgG), while somatic hypermutation introduces point mutations in the variable regions after antigen exposure, refining the affinity of antibodies. Gene rearrangement refers broadly to the process of recombining gene segments to create specific receptor genes but does not encompass the additional variability that occurs at junctions as effectively as junctional diversity does.