Novel mRNA-based vaccines have been proven powerful tools to combat the global pandemic caused by SARS-CoV2 with BNT162b2 (trade name: Comirnaty) efficiently protecting individuals from COVID-19 across a broad age range. Still, it remains largely unknown how renal insufficiency and immunosuppressive medication affect development of vaccine induced immunity. We therefore comprehensively analyzed humoral and cellular responses in kidney transplant recipients after the standard second vaccination dose. As opposed to all healthy vaccinees and the majority of hemodialysis patients, only 4/39 and 1/39 transplanted individuals showed IgA and IgG seroconversion at day 8±1 after booster immunization with minor changes until day 23±5, respectively. Although most transplanted patients mounted spike-specific T helper cell responses, frequencies were significantly reduced compared to controls and dialysis patients, accompanied by a broad impairment in effector cytokine production, memory differentiation and activation-related signatures. Spike-specific CD8 + T cell responses were less abundant than their CD4 + counterparts in healthy controls and hemodialysis patients and almost undetectable in transplant patients. Promotion of anti-HLA antibodies or acute rejection was not detected after vaccination. In summary, our data strongly suggest revised vaccination approaches in immunosuppressed patients, including individual immune monitoring for protection of this vulnerable group at risk to develop severe COVID-19.

Natural killer (NK) cell infusions can induce remissions in subsets of patients with different types of cancer. The optimal strategies for NK cell activation prior to infusion are still under debate. There is recent evidence that NK cells can acquire long-term functional competence by preactivation with the cytokines IL-12/15/18. The mechanisms supporting the maintenance of long-term NK cell antitumor activity are incompletely understood. Here, we show that NK cells preactivated in vitro with IL-12/15/18, but not with IL-15 alone, maintained high antitumor activity even 1 mo after transfer into lymphopenic RAG-2The NK cell intrinsic ability for IFNg production coincided with demethylation of the conserved non-coding sequence (CNS) 1 in the Ifng locus, previously shown to enhance transcription of Ifng. In a xenograft melanoma mouse model, human IL-12/15/18-preactivated NK cells rejected tumors more efficiently. In RAG-2C T cells further improved the long-term competence of NK cells for IFNg production that was dependent on IL-2. CD4C T cell activation during homeostatic proliferation required macrophages and further promoted the long-term NK cell antitumor activity. Thus, NK cells can "remember" a previous exposure to cytokines by epigenetic imprinting resulting in a remarkable stability of the IFNg-producing phenotype after adoptive transfer. In addition, our results support combination of cytokine-preactivated NK cells with CD4 C T cell activation upon lymphopenic conditioning to achieve long-term NK cell effector function for cancer immunotherapy.