Objectives To report clinical outcome, development of humoral and T-cell mediated immunity in convalescent COVID-19 people with multiple sclerosis (pwMS) treated with ofatumumab in the ALITHIOS study from a single center. Methods Testing for SARS-Cov2 IgG antibodies was performed on two occasions with at least three months apart between the two testing. During the second antibody testing, interferon-γ ELISpot was used to assess cellular immunity. Results All four subjects had mild COVID-19 infection without any sequelae. In all subjects except subject 2, COVID-19 was confirmed with PCR. Subjects 1, 2 and 4 had normal levels of IgM and IgG without measurable counts of CD19 cells prior to COVID-19. Subject 3 administered the last dose of ofatumumab 24 days prior to COVID-19 symptoms, but had a gap of 28 weeks of ofatumumab application beforehand due to low IgM levels. Subject 4 received COVID-19 vaccinations before second testing, so second testing and T-cell immunity testing were not performed. Subjects who were CD19 depleted did not had measurable levels of SARS-Cov2 IgG antibodies. Subject 3 had first and second SARS-COV2 titer of 118 U/ml and > 250 U/ml, respectively. All three pwMS showed T cell immunity against SARS-CoV-2. Quotient of basal spots divided by interferon-γ secreting spot forming units were 4, 8 and 14.7 SI in subjects 1, 2 and 3, respectively (>3 considered reactive). Conclusion While no antibody response was observed in pwMS who were CD19+ lymphocyte depleted, T cell immunity against SARS-CoV-2 was observed in all three pwMS treated with ofatumumab.

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Zusammenfassung: Ein diagnostisch wichtiges Kriterium der unspezifischen zellulären Immunität ist die Aktivität natürlicher Killerzellen (NK‐Zellen). Diese wird überwiegend mit der kolorimetrischen MTT‐Methode bestimmt. Eine neue zeitsparende fluorimetrische Methode1, 2 verbessert signifikant die Reproduzierbarkeit und Präzision aufgrund standardisierbarer E:T‐Verhältnisse, detektiert ausschließlich lytische Ereignisse und erlaubt zusätzlich Aussagen über den Aktivierungsstatus von NK‐Zellpopulationen vor und nach Stimulation. Eine optimale Testung mit Immunmodulatoren wird durch eine sensitive, multiparametrische Analyse ermöglicht. Die fluorimetrische Methode1, 2 bietet gravierende Vorteile im Vergleich zum MTT‐Test, der nur die metabolische Aktivität an Dehydrogenase wertet.