To assess whether the activation of MAIT cells by Leishmania is triggered in a time-, dose-, and MR1-restricted manner, whole blood samples from healthy adults were incubated with live Leishmania promastigotes and the expression of CD69 by MAIT cells (CD161highTRAV1-2+ cells) was monitored from 0 to 60 minutes (before 4h incubation with brefeldin) and at 100 to 0.1 multiplicity of infection (MOI). Here, CD69 is linked to infection.