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.