Document Detail


On sexual dimorphism in immune function.
MedLine Citation:
PMID:  18926977     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Sexual dimorphism in immune function is a common pattern in vertebrates and also in a number of invertebrates. Most often, females are more 'immunocompetent' than males. The underlying causes are explained by either the role of immunosuppressive substances, such as testosterone, or by fundamental differences in male and female life histories. Here, we investigate some of the main predictions of the immunocompetence handicap hypothesis (ICHH) in a comparative framework using mammals. We focus specifically on the prediction that measures of sexual competition across species explain the observed patterns of variation in sex-specific immunocompetence within species. Our results are not consistent with the ICHH, but we do find that female mammals tend to have higher white blood cell counts (WBC), with some further associations between cell counts and longevity in females. We also document positive covariance between sexual dimorphism in immunity, as measured by a subset of WBC, and dimorphism in the duration of effective breeding. This is consistent with the application of 'Bateman's principle' to immunity, with females maximizing fitness by lengthening lifespan through greater investment in immune defences. Moreover, we present a meta-analysis of insect immunity, as the lack of testosterone in insects provides a means to investigate Bateman's principle for immunity independently of the ICHH. Here, we also find a systematic female bias in the expression of one of the two components of insect immune function that we investigated (phenoloxidase). From these analyses, we conclude that the mechanistic explanations of the ICHH lack empirical support. Instead, fitness-related differences between the sexes are potentially sufficient to explain many natural patterns in immunocompetence.
Authors:
Charles L Nunn; Patrik Lindenfors; E Rhiannon Pursall; Jens Rolff
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Philosophical transactions of the Royal Society of London. Series B, Biological sciences     Volume:  364     ISSN:  1471-2970     ISO Abbreviation:  Philos. Trans. R. Soc. Lond., B, Biol. Sci.     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2008-11-21     Completed Date:  2009-01-15     Revised Date:  2010-09-21    
Medline Journal Info:
Nlm Unique ID:  7503623     Medline TA:  Philos Trans R Soc Lond B Biol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  61-9     Citation Subset:  IM    
Affiliation:
Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany.
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MeSH Terms
Descriptor/Qualifier:
Animals
Female
Humans
Immunity*
Immunocompetence
Insects / immunology
Leukocyte Count
Longevity
Male
Mammals / immunology
Models, Immunological
Sex Characteristics*
Grant Support
ID/Acronym/Agency:
//Biotechnology and Biological Sciences Research Council
Comments/Corrections

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