FAS and Plasmodium vivax malaria: To understand whether and how T-bethi atypical MBCs participate in immune responses to acute P. vivax infection, we further characterized the ex vivo functional profile of these MBCs by flow cytometry for inhibition markers (FcRL4, FcRL5 and CD95), activation markers (CD11c, CD40, CD69, CD86, HLA-DR and IL-21R) and chemokine receptor (CXCR5 and CCR7) expression in independent acute vivax malaria patients (n = 10) (Fig. 4).