Evaluation of intervention strategy based on CMV-specific immune responses after allogeneic SCT.

Late occurring CMV disease is an important problem after allogeneic SCT and has been associated with poor CMV-specific immunity. We conducted a prospective study of 58 patients studied at 3-6 months after allo-SCT, to base the antiviral therapy on monitoring of CMV-specific immunity. Reactivation of CMV was measured by quantitative PCR, and intracellular IFN-gamma production was analysed by FACS and enzyme-linked immunospot. Antiviral therapy was deferred in patients with documented CMV-specific immunity without symptoms of CMV disease or severe GVHD. Nineteen episodes of CMV reactivation were assessable. The strategy was correctly applied in 16/19 episodes. Therapy was deferred in 5/19 (none of these patients developed CMV disease) and was given according to the strategy in 11/19 episodes. Two patients received antiviral therapy despite having T cell-specific immunity. There was a tendency that patients with late CMV reactivation had weak CD8 T cell immunity at 3 months (P=0.06). The donors' serostatus influenced the strength of both CD4 and CD8 immunity at 3 months after SCT (P<0.01). There was no effect as regards the type of conditioning, donor type, stem cell source or acute GVHD. Monitoring the immunity of SCT patients may allow more targeted use of antiviral therapy.