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This article is the author’s final published version in Volume 8, Issue 4, May 2021, Article number e1017.

The published version is available at Copyright © Anagnostouli et al.


Dimethyl fumarate (DMF), approved for relapsing-remitting multiple sclerosis (RRMS), exerts immune-mediated mechanisms crucial for T-cell survival and migration, preferentially reducing CD8+ T cells.1 Although baseline absolute lymphocyte count (ALC) is considered the most critical predictor of developing lymphopenia,2 it was recently concluded that lymphocyte subset monitoring is not required for safety vigilance because T-cell subset reduction does not increase risks for serious infections.3 We present 2 young patients with RRMS, under DMF treatment, negative for HIV and SARSCoV-2 (by RT-PCR in nasal swab) and with normal follow-up white blood cell (WBC)/ALC counts, who developed severe herpes zoster (HZ) infection with normal ALC but low CD8+ and high CD56bright natural killer (NK) cells, and discuss the potential significance of T-cell immunophenotyping in HZ manifestation.

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This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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