To evaluate the impact of MR1 blockade on the phagocytic capacity and oxidative potential of circulating neutrophils and monocytes, whole blood samples from non-infected (NI) and asymptomatic (AS) individuals, as well as patients with visceral leishmaniasis before (LV-BT) and after (LV-AT) treatment were stimulated with live L. infantum promastigotes in the absence/presence of α-MR1 mAb. The gene discussed is MR1; the disease is visceral leishmaniasis.