• Open Access

PERSPECTIVE ARTICLE: Why do adaptive immune responses cross-react?

Authors

  • Karen J. Fairlie-Clarke,

    1. Institutes of Evolution, Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, King’s Buildings, Edinburgh, UK
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  • David M. Shuker,

    1. Institutes of Evolution, Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, King’s Buildings, Edinburgh, UK
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  • Andrea L. Graham

    1. Institutes of Evolution, Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, King’s Buildings, Edinburgh, UK
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Andrea L. Graham, Institutes of Evolution, Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, King’s Buildings, Ashworth Laboratories, Edinburgh EH9 3JT, UK. Tel.: +44 (0) 131 650 8655; fax: +44 (0) 131 650 6564; e-mail: andrea.graham@ed.ac.uk

Abstract

Antigen specificity of adaptive immune responses is often in the host’s best interests, but with important and as yet unpredictable exceptions. For example, antibodies that bind to multiple flaviviral or malarial species can provide hosts with simultaneous protection against many parasite genotypes. Vaccinology often aims to harness such imprecision, because cross-reactive antibodies might provide broad-spectrum protection in the face of antigenic variation by parasites. However, the causes of cross-reactivity among immune responses are not always known, and here, we explore potential proximate and evolutionary explanations for cross-reactivity. We particularly consider whether cross-reactivity is the result of constraints on the ability of the immune system to process information about the world of antigens, or whether an intermediate level of cross-reactivity may instead represent an evolutionary optimum. We conclude with a series of open questions for future interdisciplinary research, including the suggestion that the evolutionary ecology of information processing might benefit from close examination of immunological data.

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