Post-Transplant Immune Monitoring In Patients Receiving Allogeneic Stem Cell Transplantation

There are still substantial morbidity and mortality caused by insufficient immunologic recovery after allo-HSCT. In this context, we attempt to evaluate the clinical relevance of immune monitoring in allo-HSCT recipients.

Fifty five patients who underwent allo-HSCT between 2008 and 2012 were included. Peripheral blood samples were drawn from recipients before transplant, and on 4, 8, 12, 24, 36 and 48 weeks after transplant. Each blood samples were analyzed by multi-color flow cytometry for determining lymphocyte subsets. MNC were separated from blood specimen, and analyzed for the quantitation of Treg with the use of real-time PCR. We also examined T cell derived IFN-r by using in vitro culture, intracellular staining, and flow cytometry analysis.

The median age was 43, and AML was the most common reason for transplantation (49.1%). Grade II or more aGVHD occurred in 36.4% of cases, and 49.1% exhibited moderate or severe cGVHD. The differences in the proportion (%) and the absolute number (/uL) of CD4+, CD8+ cells, CD4+ derived IFN-r (%), CD8+ derived IFN-r (%), and Treg (%) between the groups (Gr. II or more aGVHD (+) vs (-); moderate or severe cGVHD (+) vs (-)) were compared by Two sample t-test. Patients with Gr. II or more aGVHD showed decreased CD4+ count at 4, 8 and 12 weeks, but showed rather higher CD8+ count at 8 weeks after transplant. T-cell secretion function assessed by IFN-r (%), and Treg (%) was similar between two groups within 12 weeks after transplant. In case of cGVHD, both CD4+ and CD8+ count tended to be higher in patients with moderate or severe cGVHD, and the trends lasted for up to 48 weeks from allo-HSCT. Treg (%) was almost consistently lower throughout the period in these patients. There were 12 relapses within follow up period (median 36.1 months), and higher slope of post-transplant increase in CD8+ count and CD8 derived IFN-r were identified as protective factors for disease relapse.

In view of the results so far achieved, slow recovery of CD8 count and function might be associated with disease relapse. However, this is still a preliminary data, and warrants further evaluation.

No relevant conflicts of interest to declare.