An essential feature of the adaptive immune system is the proliferation of antigen-specific lymphocytes during an immune reaction to form a large pool of effector cells. This proliferation must be regulated to ensure an effective response to infection while avoiding immunopathology. Recent experiments in mice have demonstrated that the expansion of a specific clone of T cells in response to cognate antigen obeys a striking inverse power law with respect to the initial number of T cells. Here, we show that such a relationship arises naturally from a model in which T cell expansion is limited by decaying levels of presented antigen. The same model also accounts for the observed dependence of T cell expansion on affinity for antigen and on the kinetics of antigen administration. Extending the model to address expansion of multiple T cell clones competing for antigen, we find that higher-affinity clones can suppress the proliferation of lower-affinity clones, thereby promoting the specificity of the response. Using the model to derive optimal vaccination protocols, we find that exponentially increasing antigen doses can achieve a nearly optimized response. We thus conclude that the dynamics of presented antigen is a key regulator of both the size and specificity of the adaptive immune response.
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T cell immune responses deciphered
An immune response involves a coordinated orchestra of antigen-recognizing cells ( e.g. , T cells) and signaling molecules to mount a specific response against a pathogen. Although systems immunology offers a growing list of molecular interactions that are involved in antigen-specific immune responses, an understanding of how a response is mediated by different antigen characteristics is still lacking. On page 880 of this issue, Achar et al. ( 1 ) address this question by using a robotic platform to survey a broad range of functional T cell responses to different antigen stimulations. Using machine learning, they construct a simplified map that separates six different stereotypical classes of antigen-dependent immune responses. Understanding this antigen-encoding could help guide immunotherapy, including engineering chimeric antigen receptor (CAR)–T cells and identifying vaccine antigens.
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- Award ID(s):
- 2045054
- PAR ID:
- 10337466
- Date Published:
- Journal Name:
- Science
- Volume:
- 376
- Issue:
- 6595
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 796 to 797
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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