Tc1 Clonal T Cell Expansion during Chronic Graft-versus-Host Disease–Associated Hypereosinophilia

Although hypereosinophilia (HE) associated with chronic graft-versus-host disease (GVHD) has long been recognized, biological data on this phenomenon are scarce. Here we compare patients with chronic GVHD with HE together with a clonal T cell expansion and control patients with acute or chronic GVHD but without HE. These clonal expansions share a CD8+ TC1 phenotype rather than a CD4+ Th2 profile. In contrast to the drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, these allogeneic CD8+ clones do not recognize the epitopes of herpesviruses. Furthermore, these TC1 clones do not produce IL-17 as described in the DRESS syndrome.