Seminar of Prof Jean-Claude WEILL

Title: How humans respond to vaccines? Abstract : We have isolated anti-smallpox memory B cells in people vaccinated more than 40 years ago and analyze their repertoire, phenotype and transcriptional signature in order to find out what could control their exceptional longevity These cells are “normal immortal cells” with no sign of senescence and cancerization and will react and produce protective antibodies if confronted with the corresponding pathogen. (Chappert et al, Immunity, October, 2022). There is an unexplained paradox in human immunology: How humans can produce highly mutated protective antibodies when immunized or infected with T independent highly pathogenic encapsulated bacteria which cannot induce an ongoing hypermutation process within a germinal center. We have studied longitudinally which B cell subset is involved in response to the T-independent non-conjugated pneumococcal vaccine and showed that it mobilizes marginal zone B cells pre-diversified against gut bacterial antigens (Weller et al, Science Immunology, January 2023).