PDCD1 and malaria: Naturally acquired malaria in children induces upregulation of CTLA‐4, PD‐1, LAG‐3 and TIM‐3, which are all associated with downregulation of protective immune responses and increased morbidity.94, 95, 128, 129, 130, 131 The mechanism of suppression is partially attributable to Tregs, which typically have high expression of CTLA‐4.94