SARS-CoV-2-Specific Cell-Mediated Immunity in Kidney Transplant Recipients Recovered from COVID-19.

Fernández-Ruiz, Mario; Olea, Beatriz; Giménez, Estela; Laguna-Goya, Rocío; Trujillo, Hernando; Caravaca-Fontán, Fernando; Gutiérrez, Eduardo; López-Medrano, Francisco; Remigia, María José; Almendro-Vazquez, Patricia; Polanco, Natalia; González, Esther; Ruiz-Merlo, Tamara; Parra, Patricia; San Juan, Rafael; Andrés, Amado; Navarro, David; Aguado, José María

BACKGROUND The magnitude and kinetics of severe acute respiratory syndrome coronavirus 2-specific cell-mediated immunity (SARS-CoV-2-CMI) in kidney transplant (KT) recipients remain largely unknown. METHODS We enumerated SARS-CoV-2-specific interferon-γ-producing CD69 CD4 and CD8 T-cells at months 4 and 6 from the diagnosis of coronavirus disease 2019 (COVID-19) in 21 KT recipients by intracellular cytokine staining. Overlapping peptides encompassing the SARS-CoV-2 spike (S) glycoprotein N-terminal 1- to 643-amino acid sequence and the membrane protein were used as stimulus. SARS-CoV-2 IgG antibodies targeting the S1 protein were assessed by ELISA at month 6. RESULTS Detectable (≥0.1%) SARS-CoV-2-specific CD4 T-cell response was found in 57.1% and 47.4% of patients at months 4 and 6. Corresponding rates for CD8 T-cells were 19.0% and 42.1%, respectively. Absolute SARS-CoV-2-specific T-cell counts increased from month 4 to month 6 in CD8 (P-value = 0.086) but not CD4 subsets (P-value = 0.349). Four out of 10 patients with any detectable response at month 4 had lost SARS-CoV-2-CMI by month 6, whereas 5 out of 9 patients mounted SARS-CoV-2-CMI within this period. All but two patients (89.5%) tested positive for SARS-CoV-2 IgG. Patients lacking detectable SARS-CoV-2-specific CD4 response by month 6 were more likely to be under tacrolimus (100.0% versus 66.7%; P-value = 0.087) and to have received tocilizumab for the previous COVID-19 episode (40.0% versus 0.0%; P-value = 0.087). CONCLUSIONS Although still exploratory and limited by small sample size, the present study suggests that a substantial proportion of KT recipients exhibited detectable SARS-CoV-2-CMI after 6 months from COVID-19 diagnosis.