SARS-CoV2 mRNA-vaccination-induced immunological memory in human non-lymphoid and lymphoid tissues.

Tissue-resident lymphocytes provide organ-adapted protection against invading pathogens. Whereas their biology has been examined in great detail in various infection models, their generation and functionality in response to vaccination has not been comprehensively analyzed in humans. We therefore studied SARS-CoV2 mRNA-vaccine-specific T cells in surgery specimens of kidney, liver, lung, bone marrow and spleen in comparison to paired blood samples from largely virus-naïve individuals. As opposed to lymphoid tissues, non-lymphoid organs harbored significantly elevated frequencies of Spike-specific CD4+ T cells compared to blood showing hallmarks of tissue residency and an expanded memory pool. Organ-derived CD4+ T cells further exhibited increased polyfunctionality over those detected in blood. Single-cell RNA sequencing together with T cell receptor repertoire analysis indicated that the clonotype rather than organ origin is a major determinant of transcriptomic state in vaccine-specific CD4+ T cells. In summary, our data demonstrate that SARS-CoV2 vaccination entails acquisition of tissue memory and residency features in organs distant from the inoculation site, thereby contributing to our understanding of how local tissue protection might be accomplished.