Extensive renewal of the T cell repertoire following autologous stem cell transplant in MS

February 17, 2014

A new study describes the complexity of the new T cell repertoire following immune-depleting therapy to treat multiple sclerosis, improving our understanding of immune tolerance and clinical outcomes.

In the Immune Tolerance Network's (ITN) HALT-MS study, 24 patients with relapsing, remitting received high-dose immunosuppression followed by a transplant of their own stem cells, called an autologous , to potentially reprogram the so that it stops attacking the brain and spinal cord. Data published today in the Journal of Clinical Investigation quantified and characterized T cell populations following this aggressive regimen to understand how the reconstituting immune system is related to patient outcomes.

ITN investigators used a high-throughput, deep-sequencing technology (Adaptive Biotechnologies, ImmunoSEQTM Platform) to analyze the T cell receptor (TCR) sequences in CD4+ and CD8+ cells to compare the repertoire at baseline pre-transplant, two months post-transplant and 12 months post-transplant.

Using this approach, alongside conventional flow cytometry, the investigators found that CD4+ and CD8+ lymphocytes exhibit different reconstitution patterns following transplantation. The scientists observed that the dominant CD8+ T cell clones present at baseline were expanded at 12 months post-transplant, suggesting these clones were not effectively eradicated during treatment. In contrast, the dominant CD4+ T cell clones present at baseline were undetectable at 12 months, and the reconstituted CD4+ T cell repertoire was predominantly comprised of new clones.

The results also suggest the possibility that differences in repertoire diversity early in the reconstitution process might be associated with . Nineteen patients who responded to treatment had a more diverse repertoire two months following transplant compared to four patients who did not respond. Despite the low number of non-responders, these comparisons approached statistical significance and point to the possibility that complexity in the T cell compartment may be important for establishing .

This is one of the first studies to quantitatively compare the baseline T cell repertoire with the reconstituted repertoire following autologous stem cell transplant, and provides a previously unseen in-depth analysis of how the immune system reconstitutes itself following immune-depleting therapy.

Explore further: Researchers look to mathematics, nature, to understand the immune system and its role in cancer

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