Spike-specific T-cell responses in patients with COVID-19 successfully treated with neutralizing monoclonal antibodies against SARS-CoV-2

Abstract

Objectives: Neutralizing monoclonal antibodies (moAbs) improves clinical outcomes in patients with COVID-19 when administered during the initial days of infection. The action of moAbs may impair the generation or maintenance of effective immune memory, similar to that demonstrated in other viral diseases. We aimed to evaluate short-term memory T-cell responses in patients effectively treated with bamlanivimab/etesevimab, casirivimab/imdevimab, or sotrovimab (SOT).

Methods: Spike (S)-specific T-cell responses were analyzed in 23 patients with COVID-19 (vaccinated or unvaccinated) before and after a median of 50 (range: 28-93) days from moAb treatment, compared with 11 vaccinated healthy controls. T-cell responses were measured by interferon-γ-enzyme-linked immunospot and flow cytometric activation-induced marker assay.

Results: No statistically significant difference in S-specific T-cell responses was observed between patients treated with moAb and vaccinated healthy controls. Bamlanivimab/etesevimab and casirivimab/imdevimab groups showed significant increases in cellular responses in paired baseline/postrecovery series, as well as vaccinated patients receiving SOT. In contrast, unvaccinated patients prescribed SOT presented no statistically significant increases in T-cell-responses, suggesting diverse impacts of different moAbs on the evolution of S-specific T-cell responses in vaccinated and unvaccinated patients.

Conclusion: The moAbs did not hinder short-term memory S-specific T-cell responses in the overall group of patients; however, differences among moAbs must be further investigated both in vaccinated and unvaccinated individuals.

Keywords: CD4; CD8; COVID-19; Immunity; Monoclonal antibodies; SARS-CoV-2; T-cell response.

Figure 1

S-specific immune responses at T1. (a) Schematic summary of individual S-specific immune responses for COVID-19 NV, V, and H donors participants. (b) S-specific IFN-γ-releasing cells (left), AIM+(OX40+CD137+) CD4+ T-cells (middle), and AIM+(CD69+CD137+)CD8+ T-cells (right) measured after stimulation of PBMCs with peptides derived from the S protein of SARS-CoV-2. IFN-γ-releasing cells are reported as SFU/10⁶ PBMCs. AIM+ responses are reported as stimulation index, calculated as described in methods. Statistical comparisons across groups were performed with the Kruskal-Wallis test. P-value is indicated for each pairwise comparison. Horizontal bars indicate the median. Abbreviations: AIM, activation-induced cell marker; CD, cluster of differentiation; ELISpot, Enzyme-linked immunospot; H, healthy; IFN, interferon; Ig, immunoglobulin; NV, unvaccinated; PBMC, peripheral blood mononuclear cells; S, spike; SFU, stimulating forming unit; V, vaccinated.

Figure 2

S-specific immune responses at T2. (a) Schematic summary of individual S-specific immune responses for NV and V COVID-19 participants. (b) S-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells at T2 in all COVID-19 patients and H donors. Statistical comparisons were performed with the Mann-Whitney test. P-value is indicated for each comparison. Horizontal bars indicate the median. Abbreviations: AIM, activation-induced cell marker; CD, cluster of differentiation; ELISPOT, Enzyme-linked immunospot; H, healthy; IFN, interferon; NV, unvaccinated; PBMC, peripheral blood mononuclear cells; S, spike; SFU, stimulating forming unit; V, vaccinated.

Figure 3

Comparison of S-specific T-cell responses between V and NV patients. (a) S-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells measured in NV, V, and H donors participants at T2. Statistical comparisons across groups were performed with the Kruskal-Wallis test. P-value is indicated for each pairwise comparison. Horizontal bars indicate the median. (b-c) T1/T2 pairwise comparison of S-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells measured in NV (b) and V (c) group. Statistical comparison for T1/T2 pairwise was performed by the Wilcoxon matched-pairs signed rank test. P-value is indicated for each comparison. Abbreviations: AIM, activation-induced cell marker; CD, cluster of differentiation; ELISPOT, Enzyme-linked immunospot; H, healthy; IFN, interferon; NV, unvaccinated; PBMC, peripheral blood mononuclear cells; S, spike; SFU, stimulating forming unit; V, vaccinated.

Figure 4

Comparison of S-specific T-cell responses between monoclonal antibodies treatment groups. (a) S-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells were measured in patients treated with BMT/REG, SOT, or in H-controls at T2. Statistical comparisons across groups were performed with the Kruskal-Wallis test. P-value is indicated for each pairwise comparison. Horizontal bars indicate the median. (b-c) T1/T2 pairwise comparison of S-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells measured in patients treated with SOT (b) or BMT/REG (c). Statistical comparison for T1/T2 pairwise was performed by the Wilcoxon matched-pairs signed rank test. P-value is indicated for each comparison. Abbreviations: AIM, activation-induced cell marker;; CD, cluster of differentiation; BMT, bamlanivimab/etesevimab; ELISPOT, Enzyme-linked immunospot; H, healthy; IFN, interferon; PBMC, peripheral blood mononuclear cells; REG, casirivimab/imdevimab; S, spike; SFU, stimulating forming unit; SOT, sotrovimab.

Figure 5

T1/T2 pairwise comparison of spike-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells measured in unvaccinated patients treated with BMT/REG (a) and SOT (b). Statistical comparison for T1/T2 pairwise was performed by the Wilcoxon matched-pairs signed rank test. P-value is indicated for each comparison. Abbreviations: AIM, activation-induced cell marker; CD, cluster of differentiation; BMT, bamlanivimab/etesevimab; ELISPOT, Enzyme-linked immunospot; IFN, interferon; PBMC, peripheral blood mononuclear cells; REG, casirivimab/imdevimab; SFU, stimulating forming unit; SOT, sotrovimab.

Figure 6

T1/T2 pairwise comparison of spike-specific IFN-γ-releasing cells (left), AIM+CD4+ T-cells (middle), and AIM+CD8+ T-cells measured in vaccinated patients treated with SOT. Statistical comparison for T1/T2 pairwise was performed by the Wilcoxon matched-pairs signed rank test. P-value is indicated for each comparison. Abbreviations: AIM, activation-induced cell marker; ELISPOT, Enzyme-linked immunospot; IFN, interferon; SFU, stimulating forming unit; SOT, sotrovimab.