Discrimination of acute graft-versus-host disease from infections by enumeration of peripheral blood interferon-γ spot-forming cells

Infections may coexist and in certain circumstances aggravate acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation. Early detection of aGVHD is often difficult in patients with concurrent infections. Using an enzyme-linked immunospot assay that reflects ongoing immune status in vivo, we enumerated spot-forming cells (SFCs) for interferon (IFN)-gamma, interleukin (IL)-4, and IL-12 in peripheral blood from 56 patients with hematological disorders. Eleven patients had viral, fungal, or bacterial systemic infections during first 10 weeks posttransplant. Of these, six patients with grade 0-I aGVHD showed normal levels of IFN-gamma SFCs. On the other hand, IFN-gamma SFCs were elevated in five patients with grade II-IV aGVHD. These data indicate that increased IFN-gamma SFCs seemed to be correlated with clinically significant aGVHD, but not with infection itself. IL-4 and IL-12 SFCs increased in some patients with infections, irrespective of the presence of aGVHD. Thus, IFN-gamma SFCs may be used to distinguish systemic infections from aGVHD.