tetano
Editor, Senior Moderator
Enferm Infecc Microbiol Clin (Engl Ed)
. 2026 May;44(5):503146.
doi: 10.1016/j.eimce.2026.503146.
SARS-CoV-2 spike-directed T cells and anti-receptor-binding-domain antibodies in hematological patients receiving three mRNA COVID-19 vaccine doses
Diego Carretero[SUP] 1 [/SUP], Estela Giménez[SUP] 2 [/SUP], Ariadna Pérez[SUP] 3 [/SUP], Rafael Hernani[SUP] 3 [/SUP], José Luis Piñana[SUP] 3 [/SUP], Carlos Solano[SUP] 4 [/SUP], David Navarro[SUP] 5 [/SUP], Eliseo Albert[SUP] 6 [/SUP]
Affiliations
Introduction: Studies assessing SARS-CoV-2 antibodies and functional T-cell responses in hematological patients following receipt of a three-dose mRNA vaccine schedule have yielded conflicting results.
Methods: We conducted a retrospective observational study in which we measured SARS-CoV-2-S-directed cytokine-producing CD8[SUP]+[/SUP] and CD4[SUP]+[/SUP] T cells by flow cytometry and anti-receptor-binding domain (RBD) total antibodies in 32 hematological patients, including 10 allogeneic hematopoietic stem cell transplant (allo-HCT) recipients and 22 non-transplanted individuals. Immunological testing was performed after the second COVID-19 mRNA vaccine dose (Post-2D), prior to the third dose (Pre-3D), and after the third dose (Post-3D).
Results: At Post-2D, 72.4%, 44.8%, and 37.9% of participants had detectable IFN-γ-, TNF-α-, and IFN-γ/TNF-α-producing CD8[SUP]+[/SUP] T cells, respectively. A decrease in the rate of detectable and frequencies of monofunctional and bifunctional SARS-CoV-2-S CD8[SUP]+[/SUP] T-cell responses was observed at Pre-3D. By contrast, the number of participants displaying detectable cytokine-producing CD4[SUP]+[/SUP] T-cell responses and their frequencies were rather conserved at all testing times. Receiving a 3D had no significant impact on the rate of detection and frequencies of monofunctional and bifunctional SARS-CoV-2-S-directed T-cell subsets. Anti-RBD total antibody responses were detected in approximately half of participants at all time points. Overall, anti-RBD antibody levels decreased at Pre-3D and then increased following the 3D.
Conclusion: Administration of the 3D may have a limited impact on both cellular and humoral immune responses in a substantial proportion of hematological patients. These findings highlight the heterogeneity of vaccine-induced immunity and support the role of combined immune monitoring and alternative protective strategies for selected patients.
Keywords: Anti-RBD antibodies; Anticuerpos anti-RBD; Booster; COVID-19 vaccine; Dosis de refuerzo; Inmunidad T; SARS-CoV-2; T-cell immunity; Vacuna COVID-19.
. 2026 May;44(5):503146.
doi: 10.1016/j.eimce.2026.503146.
SARS-CoV-2 spike-directed T cells and anti-receptor-binding-domain antibodies in hematological patients receiving three mRNA COVID-19 vaccine doses
Diego Carretero[SUP] 1 [/SUP], Estela Giménez[SUP] 2 [/SUP], Ariadna Pérez[SUP] 3 [/SUP], Rafael Hernani[SUP] 3 [/SUP], José Luis Piñana[SUP] 3 [/SUP], Carlos Solano[SUP] 4 [/SUP], David Navarro[SUP] 5 [/SUP], Eliseo Albert[SUP] 6 [/SUP]
Affiliations
- PMID: 42108004
- DOI: 10.1016/j.eimce.2026.503146
Introduction: Studies assessing SARS-CoV-2 antibodies and functional T-cell responses in hematological patients following receipt of a three-dose mRNA vaccine schedule have yielded conflicting results.
Methods: We conducted a retrospective observational study in which we measured SARS-CoV-2-S-directed cytokine-producing CD8[SUP]+[/SUP] and CD4[SUP]+[/SUP] T cells by flow cytometry and anti-receptor-binding domain (RBD) total antibodies in 32 hematological patients, including 10 allogeneic hematopoietic stem cell transplant (allo-HCT) recipients and 22 non-transplanted individuals. Immunological testing was performed after the second COVID-19 mRNA vaccine dose (Post-2D), prior to the third dose (Pre-3D), and after the third dose (Post-3D).
Results: At Post-2D, 72.4%, 44.8%, and 37.9% of participants had detectable IFN-γ-, TNF-α-, and IFN-γ/TNF-α-producing CD8[SUP]+[/SUP] T cells, respectively. A decrease in the rate of detectable and frequencies of monofunctional and bifunctional SARS-CoV-2-S CD8[SUP]+[/SUP] T-cell responses was observed at Pre-3D. By contrast, the number of participants displaying detectable cytokine-producing CD4[SUP]+[/SUP] T-cell responses and their frequencies were rather conserved at all testing times. Receiving a 3D had no significant impact on the rate of detection and frequencies of monofunctional and bifunctional SARS-CoV-2-S-directed T-cell subsets. Anti-RBD total antibody responses were detected in approximately half of participants at all time points. Overall, anti-RBD antibody levels decreased at Pre-3D and then increased following the 3D.
Conclusion: Administration of the 3D may have a limited impact on both cellular and humoral immune responses in a substantial proportion of hematological patients. These findings highlight the heterogeneity of vaccine-induced immunity and support the role of combined immune monitoring and alternative protective strategies for selected patients.
Keywords: Anti-RBD antibodies; Anticuerpos anti-RBD; Booster; COVID-19 vaccine; Dosis de refuerzo; Inmunidad T; SARS-CoV-2; T-cell immunity; Vacuna COVID-19.