Transport of Antibody into the Skin is Only Partially Dependent Upon the Neonatal Fc-Receptor

The dermis is the portal of entry for most vector-transmitted pathogens, making the hosts immune response at this site critical in mitigating the magnitude of infection. For malaria, antibody-mediated neutralization of Plasmodium parasites in the dermis was recently demonstrated. However, surprisingly little is known about the mechanisms that govern antibody transport into the skin. Since the neonatal Fc receptor (FcRn) has been shown to transcytose IgG into various tissues, we sought to understand its contribution to IgG transport and antibody-mediated inhibition of Plasmodium parasites following mosquito bite inoculation. Using confocal imaging, we show that the transport of an anti-Langerin mAb into the skin is only partially reduced in mice lacking FcRn. To understand the relevance of FcRn in the context of malaria infection, we use the rodent parasite Plasmodium berghei and show that the protective efficacy of a passively-administered anti-malarial antibody is reduced in the skin in FcRn deficient mice, but not to the same extent that we have previously observed in wildtype mice. Overall, our data suggest that FcRn plays a role in the transport of IgG into the skin but is not the major driver of IgG transport into this tissue. These findings have implications for the rational design of antibody-based therapeutics for malaria as well as other vector-transmitted pathogens.