Sex hormones and regulation of host responses against parasites

Abstract

Sex hormones play an influential role in the control of parasitic infection by their ability to modulate different components of both the innate and adaptive immune responses. The parasites themselves are phylogenetically diverse, target a range of different tissues, and have evolved numerous alternative strategies to evade or inhibit protective immune responses. Consequently, the influence of sex hormones on these infective agents can be complex. For example, while females exhibit greater resistance to infection by parasites including Trypanosoma cruzi, Trypanosoma brucei, Giardia lamblia, Leishmania mexicana, Plasmodium chabaudi, and Trichinella spiralis, their male counterparts are found to be more resistant to infection with Trichomonas vaganalis, Toxoplasma gondii and Schistosoma mansoni. This chapter will discuss: (1) the role of sex hormones in regulating the outcome of parasite infection, (2) mechanisms by which these hormones modulate host immune responses, and (3) the implications of these observations for the pathogenesis of human parasitic disease.