Apolipoprotein E4 prevents growth of malaria at the intraerythrocyte stage: Implications for diff erences in racial susceptibility to alzheimer's disease

ApolipoproteinE 4 (ApoE 4) has been linked to pathogenesis of Alzheimer's disease and has been suggested to be maintained through evolutionary pressure via a protective role in malaria infection. We evaluated Plasmodium falciparum viability at the intraeryth-rocyte stage by exposure to plasma from human subjects with ApoE 4/4 or ApoE 3/3. Plasma samples from ApoE 4/4 but not ApoE 3/3 donors inhibited growth and disrupted morphology of P. falciparum. Evolutionary history is characterized by war between pathogenic microorganisms and defense mechanisms countering their pathogenicities. ApoE 4 frequency is highest in sub- Saharan Africa and other isolated populations (e.g., Papua New Guinea) that exhibit endemic malaria. High ApoE frequency may of er selective advantage protecting against some infectious diseases (e.g., Plasmodium falciparum). These results implicate evolutionary pressure by malaria selecting humans with ApoE 4/4, even considering lower survival in late life. These selective advantages may be relevant in the exploration of possible disparities between Black and Whites in the incidence of Alzheimer's Disease.