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C.S. Link-Rachner et al.
fering from aGvHD ≥Grade II. A tendency towards higher TRα diversity in the memory compartment was observed in patients suffering from aGvHD compared with patients without aGvHD on day 60 (0.958911 vs. 0.918315, respec- tively), but this difference was not statistically significant. On day 180 post transplantation, comparable memory Ds values were seen for patients with and without aGvHD (0.943686 vs. 0.941054, respectively). Nevertheless, diver- sity in aGvHD patients decreased over time, while non- GvHD patients showed increasing diversity. Similarly, the mean naïve Ds was higher in aGvHD patients on day 60 than in non-GvHD patients (0.990826 vs. 0.916534, respectively), with a decrease to a mean of 0.959410 on day 180 compared to 0.95290 in non-GvHD patients. No differences were observed between patients who devel- oped aGvHD before day 60 (early) and those who devel- oped aGvHD after day 60 (late).
Chronic graft-versus-host disease occurred in 12 out of 25 patients (48.0%), with 10 patients suffering from exten- sive cGvHD. The mean Ds of the naïve compartment was higher in cGvHD patients than in non-GvHD patients at both time points (0.983022 and 0.992050 vs. 0.947150 and 0.953680, respectively). In contrast, the TCR diversity of the memory compartment tended to be lower in cGvHD patients than in patients without cGvHD (0.932145 and 0.929679 vs. 0.955514 and 0.954794 on day 60 and day 180, respectively) (Figure 6B).
Discussion
Immune reconstitution following transplantation is essential to achieve optimal outcomes with allogeneic SCT. However, detailed knowledge of TCR repertoire
Figure 4. Normalized spatial clonotype distribution. Distribution of the clonotypes is visualized by grouping them according to their proportions (rare, small, medium and large) and normalization within the UD-ATG, mmUD-ATG, UD-noATG and Haplo-PTCy groups. Clonal space distribution was calculated using a R package provided for TCR repertoire data analysis.28 Starting on the left, the first two panels represent the naïve repertoire (day 60 followed by day 180 post transplantation) and suc- cessive panels show the distribution of the memory repertoire on day 60 and day 180 post transplantation.
bone marrow transplant showed the lowest T-cell counts (P=0.007). Nevertheless, analyses of graft cell counts among the total number of CD34+ cells (x106/kg body weight) and total number of T cells showed no association with TRα diversity (Online Supplementary Figure S3). Furthermore, there was no relation between donor age and the diversity in the patient's repertoire.
Cytomegalovirus serostatus impairs T-cell receptor-α diversity
Cytomegalovirus infections impose a serious post-trans- plantation risk. The occurrence of CMV infections and CMV serostatus of patients and donors were analyzed for associations with TRα diversity. CMV infections were mainly observed within the first 60 days following trans- plantation. Ten of 25 patients suffered from CMV infec- tions during the first 60 days (Figure 5A). The correlation between CMV infection and TRα diversity is shown in Figure 5B. Statistical analysis revealed no significant differ- ences in TRα diversity for patients suffering from CMV reactivation and patients without detected CMV reactiva- tion. Significantly lower diversity in the naïve TRα reper- toire (P=0.014) was observed in patients transplanted from a CMV-seropositive donor. In the memory repertoire, a tendency towards lower diversity was also observed at both time points (mean Ds of 0.933183 and 0.936029 vs. 0.956337 and 0.950007, respectively).
Acute and chronic graft-versus-host disease in association with TCR diversity
The occurrence of aGvHD and TRα diversity for each patient is shown in Figure 6A. Sixteen (64.0%) out of 25 patients developed aGvHD, with 9 (36.0%) patients suf-
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haematologica | 2019; 104(3)