Early activation does not translate into effector differentiation of peripheral CD8T cells during the acute phase of Kawasaki disease.

Early diagnosis of acute Kawasaki disease (KD), lying in the spectrum between infectious and autoimmune diseases, can be difficult. To clarify the role of peripheral CD8T cells in KD, we examined their activation, proliferation, maturation, and effector function by four-color flow cytometry. Compared to healthy/febrile controls, acute KD patients showed striking increase in early activation marker CD69(+)CD8T cells and maturation subsets, but HLA-DR(+)CD8T cells representing late activation did not increase. Although Ki67(+)CD8T cells reflecting ongoing cell division increased in acute KD and febrile controls, absolute numbers of CD8T cells and maturation subsets decreased in acute KD versus healthy controls. Effector cells were lower in acute than in convalescent KD. Perforin(+)CD8T cells, denoting cytolytic activity, were lower in KD patients versus febrile controls. CD69(+)CD8T cells increase in acute KD but effector differentiation is absent. CD69(+)CD8T cells could be a marker to determine disease progression, treatment response, and convalescence in acute KD.