Page 175 - Haematologica May 2022

Letters to the Editor
PBMC plated for ELISpot were observed across healthy and MDS cohorts (Online Supplementary Figure S1E). Using previously published thresholds for response,1,2 non-T cell responders were seen in all cohorts (Figure 2A; red dots). Specifically, SARS-CoV-2-specific IFNg T-cell responses against the δ variant were: HV BNT162b2 95% (20/21); MDS ChAdOx1 70.6% (12/17) and MDS BNT162b2 71.4% (10/14) (Figure 2A); in stark contrast to the comparable control CEF induced effector T-cell responses across healthy and MDS samples (Figure 2A). Interestingly, significantly reduced T-cell responses were seen in MDS BNT162b2-vaccinated patients when chal- lenged with δ compared to wt variant strain (Figure 2B). Further, five MDS ChAdOx1 patients who did not have a serological response, were able to mount T-cell respons- es. Additionally, treatment with either azacytidine or cal- cineurin inhibitor cyclosporine did not impair appropriate T-cell responses. One high risk MDS BNT162b2 patient
on 5-azacytidine, who showed no neutralizing activity, showed significantly reduced T-cell response to WT and a, but not to δ variant. During the study period, the δ variant was the predominant VOC in the UK. We observed non-significant but positive correlations between serological and IFNg T-cell responses against the δ variant within the MDS vaccinated cohorts (Figure 2C). Numbers of individuals who were both serological and T- cell responders were as follows: HV 95% (20/21), MDS BNT162b2 71.4% (10/14) and MDS ChAdOx1 52.9% (9/17) (Figure 2C). In order to further investigate the cel- lular readout of vaccine efficacy, we assessed the activa- tion state of SARS-CoV-2 stimulated CD8 T cells, by measuring activation markers CD25 and CD69 cell sur- face expression by flow cytometry before and after in vitro stimulation. Despite the poorer humoral response observed in MDS-ChAdOx1 vaccinated individuals, we found significantly higher activated CD25+ and CD69+
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Figure 2. Cellular responses to BNT162b2 COVID-19 and ChAdOx1 nCoV-19 in patients with myelodysplastic syndromes. (A) Interferon g (IFNg) spot-forming units (SFU) formed after stimulation of peripheral blood mononuclear cells (PBMC) from indicated cohorts in response to indicated variants. Samples were classed as responders if >7 cytokine secreting cells/106 PBMC after correcting for background; as indicated by dashed line. Non-responders are colored as indi- cated. Wuhan strain (WT); (healthy volunteers [HV] [n=26]; MDS ChAdOx1 [n=20]; MDS BNT162b2 [n=15]); B.1.1.7; (HV [n=11]; MDS ChAdOx1 [n=11]; MDS BNT162b2 [n=15]); B.1.617.2; (HV [n=21]; MDS ChAdOx1 [n=17]; myelodysplastic syndrome (MDS) BNT162b2 [n=14]). Tukey’s multiple comparison’s test. Influenza virus positive control (CEF)= Cytomegalovirus (CMV), Epstein-Barr virus (EBV) and influenza virus positive control peptides: (B) IFNγ SFU formed after stimulation of PBMC from MDS BNT162b2 cases to indicated variants. WT (n=15); B.1.1.7 (n=11); B.1.617.2 (n=14). Tukey’s multiple comparison’s test. (C) Correlation matrices showing IFNg SFU formed after PBMC were stimulated with the B.1.617.2 variant and paired S IgG 50% effective dose (ED50) values for indicated cohorts. Correlation coefficients (rho;r), P-values, n numbers and % double positivity are given. Dashed lines represent thresholds as previously described. Pearson’s correlation test. E (i&ii). CD8+CD25+ cells (i) and CD8+CD69+ cells (ii) within the live CD3+ population after stimulation of PBMC from indi- cated cohorts in response to indicated variants. HV (n=26); MDS ChAdOx1 (n=20); MDS BNT162b2 (n=15). Tukey’s multiple comparison’s test.
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