The evolution of greater humoral immunity in females than males: implications for vaccine efficacy
Section snippets
Ontogeny of sex differences in humoral immunity
The effects of age on the humoral immune response to vaccination are well documented, yet very few studies consider both age and sex as biological variables. Sex differences are most profound in individuals after sexual maturation, and the underlying mechanisms for these differences have been attributed to both hormonal and genetic effects on the immune system. However, the interplay between age, specifically prior to sexual maturation and following reproductive senescence, and the differential
Functional significance of sex differences in humoral immunity for vaccines
Increased susceptibility to infections in infants has led to the development of many vaccines that provide protection prior to exposure. Sex differences have been reported in the antibody responses to many childhood vaccines, however these data are conflicting and limited by the number of studies that report the sex of the individuals and/or partition their data by sex. Antibody responses to diphtheria, pertussis, hepatitis A, hepatitis B, pneumococcal, rabies, human papilloma virus (HPV), and
Phylogeny of sex differences in humoral immunity
Sex differences in humoral immune responses have evolved in diverse species. In birds, for example, females exhibit higher antibody and cell-mediated immune responses to immune challenges and these effects are often most pronounced during the mating season when male testosterone concentrations are highest [52, 53]. Mounting adaptive immune responses that are necessary for clearance of microbes requires metabolic resources that might otherwise be used for other biological processes, such as
Concluding remarks
Males and females are biologically different, which impacts adaptive immune responses to diverse antigens, including vaccine antigens. The mechanisms mediating these differences, both hormonal and genetic factors, can alter humoral immune responses to vaccination and may result in sex-specific difference in vaccine efficacy across the life course. Consideration of sex differences in the design of vaccines, including those that protect against influenza, may increase vaccine efficacy. The
Conflict of interest statement
Nothing declared.
References and recommended reading
Papers of particular interest, published within the period of review, have been highlighted as:
• of special interest
•• of outstanding interest
Acknowledgements
The writing of this review was supported by the NIH/NIAID Center of Excellence in Influenza Research and Surveillance contract HHS N272201400007C.
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