MR1 and acquired polycythemia vera: Instead, a relative depletion of circulating Vδ2+ γδTCRint, and atypical CD4+CD8+ (DP) and CD4+CD8- MR1-restricted T cells was observed in the face of increasing CCL27 and IL-18 levels in PV sera, respectively, possibly reflecting their different sensitivity to activation-induced cell death (54), or homeostatic trafficking and redistribution of two cell populations competitively best poised to respond to CCR10 and IL-18R ligation (55).