Innate Lymphocytes in Young Splenocytes Promote Protection Against Plasmodium chabaudi Infection

Abstract

Abstract Immunity to malaria requires an elongated time to develop and understanding of the immune response to malaria, especially in children under five, is limited due to the lack of a reliable animal model to study the pathogenesis of the disease. By utilizing a newly developed young rodent model in our lab, we have observed that both splenocytes and purified CD4+ T cells from 8-week adult mice proliferate faster than day 15 old young mice (pups) when stimulated in vitro. Based on the proliferation pattern, we concluded that as the mice age, their cells have the potential to proliferate faster. When transferred to immunocompromised RAG1 knockout (RAG1KO) mice, both pup and adult cells protected from death. This data suggests that there is both a proliferative and responsive cell population in the splenocytes of pups that may promote protection against malaria infection in mice. To better understand this responsive cell population, we adoptively transferred splenocytes from both pups and adult mice into RAG1KO mice and infected the cell recipients with P. chabaudi. We observed higher proportions and numbers of innate lymphocytes including gamma delta (γδ) T cells and natural killer (NK) cells in the pup splenocyte recipients when compared to the adult counterparts on day 9 post-infection. However, there were significantly higher proportions of macrophages in the adult spleen cell recipients. Taken together, our findings suggest that pup cells are enriched with innate lymphocytes that may promote protection against P. chabaudi infection.