RSV-specific humoral and cellular immune responses in kidney transplant recipients

Induction of virus-specific immune responses in kidney transplant recipients (KTR) by vaccination is challenging. However, it is not well-described whether pre-existing immunity against respiratory viruses initially encountered before transplantation, like respiratory syncytial virus (RSV), is maintained. Therefore, we assessed RSV-specific humoral and cellular immune responses in KTR and controls at two timepoints during the COVID-19 pandemic. Binding and neutralizing antibodies were determined in serum samples from 64 KTR and 37 controls. Cellular immune responses were measured in a cohort subset (15 KTR, 14 controls) by stimulation of peripheral blood mononuclear cells with RSV-derived peptide pools. This was followed by phenotypic analysis using an activation-induced marker assay and cytokine release assay. RSV-specific binding IgG and neutralizing antibody titers were comparable between KTR and controls and stable over time. While total lymphocyte levels were significantly lower in KTR, relative frequencies of RSV-specific CD4 + and CD8 + memory T cells were comparable between groups. Unsupervised hierarchical clustering distinguished three cytokine production profiles with divergent RSV-specific immune responses, but KTR and controls were equally distributed throughout. Thus, KTR have comparable RSV-specific humoral and cellular immune responses to controls. Our findings suggest that pre-existing respiratory virus-specific immune responses persist under immunosuppressive treatment.