Tymic Output after Autologous Bone Marrow Transplantation (ASCT) HIV-Related Lymphoma.

Background: One of the major concern for ASCT in HIV-positive patients (pts) is that post-transplant immunosuppression might worsen the immunosuppression and enhance the HIV replication. Therefore we analyzed whether the immune system of HIV-positive pts might support an immune recovery similar to the HIV-negative pts who underwent the same ASCT program.

Methods: The kinetics and the extent of immunereconstitution were assessed by measuring: TCR excision circles (TRECs), CD4, CD8, CD56, CD4, CD45RA, CD19 cells, and HIV pro and viraemia

Results: 15 HIV-positive and 7 HIV-negative pts with relapsed DBCL underwent ASCT. Before the induction therapy TRECs/10⁶ PBMC mean value was 962±2183 and 2948±5485 in HIV-positive and HIV-negative pts respectively. The nadir was reached before ASCT (150±11 vs 927±1842). At one year the mean value of TRECs/10⁶ PBMC returned to the baseline in HIV-negative pts, while in HIV-positive pts largely overcame the baseline (2440±2799). Before the induction therapy, HIV-positive pts showed a significant lower CD4 (174±110 vs 386±200) CD56 (86±129 vs 144±92) and CD4/CD8 ratio in comparison with HIV-negative pts. CD4 count nadir was reached during aplastic period in both groups. No differences were present in the dynamics of CD4, CD45RA, CD8 and CD56 recovery between the two groups. At one year CD4 count returned to the baseline value in HIV-negative pts while in HIV-positive pts overcame 70% the baseline value. Before ASCT, all HIV-positive pts were on HAART and HIV-viraemia was <50cp/ml in 10/15; 6 pts discontinued HAART, but HIV viraemia and proviraemia did not increase significantly during the overall observational period.

Conclusions: The dynamics of the immunereconstitution was similar in HIV-positive and HIV-negative pts, but the tymic output unexpectedly seemed to be enhanced in HIV-positive pts. Supported by ISS grants.