immunodominans

Immunodominance is a phenomenon in adaptive immunity in which immune responses are focused on a subset of epitopes within an antigen. When antigen-presenting cells process a protein, T cells specific for some epitopes expand more strongly than for others, creating a hierarchy of immunogenic epitopes. Immunodominance is observed for CD8+ cytotoxic T lymphocytes and CD4+ helper T cells and can shape accompanying antibody responses.

Several factors determine which epitopes become dominant. The binding affinity and stability of peptide–MHC complexes influence presentation efficiency, as does the rate and pathway of antigen processing. Peptide abundance and turnover, the breadth of the T cell receptor repertoire, and competition among T cells for limited MHC–peptide complexes also contribute. The inflammatory environment and co-stimulatory signals further modulate the hierarchy by favoring certain epitopes over others.

Implications of immunodominance include the potential for pathogens to escape immunity by mutating dominant epitopes or shielding them through glycosylation or conformational changes. A focused response on a few epitopes can limit breadth and durability of protection, while in some cases subdominant epitopes may become relevant in chronic infections or with altered antigen exposure.

In vaccine design and immunotherapy, immunodominance is a consideration for achieving broad, durable protection. Strategies aim to broaden the epitope repertoire or redirect responses toward conserved, protective epitopes, often using adjuvants or epitope-based formulations. Epitope mapping and assays like ELISPOT, intracellular cytokine staining, and tetramer staining are used to characterize immunodominance patterns.