A follow-up study by Mewono et al. (2009) demonstrated that IL-21 was induced following the stimulation of peripheral blood mononuclear cells (PBMCs) isolated from P. falciparum-experienced human subjects as compared with P. falciparum-naïve controls in response to two malaria vaccine candidates, the P. falciparum glutamate-rich protein (PfGLURP) or the P. falciparum merozoite surface protein 3 (PfMSP-3) (Mewono et al., 2009). This evidence concerns the gene IL21 and malaria.