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SUMMARY:Maintaining diversity while maximising affinity - IL-21 and the ba
 lancing act of B cell selection - Dr Isaak Quast\; Monash University 
DTSTART:20230322T143000Z
DTEND:20230322T153000Z
UID:TALK197827@talks.cam.ac.uk
CONTACT:Bobbie Claxton
DESCRIPTION:Germinal center (GC) formation in response to infection or vac
 cination relies on the coordinated behavior of T and B cells. IL-21\, a pl
 eiotropic\, T cell derived cytokine\, is a central modulator of GC size\, 
 maintenance and output and studying how it exerts its actions provides an 
 opportunity to understand GC dynamics. Following this theorem\, we genetic
 ally restricted IL-21 production and receipt in vivo to show how its indep
 endent actions on T and B cells combine to regulate the GC. During respons
 e initiation\, IL-21 promotes CD4 T cell expansion and Tfh differentiation
  in a dose-dependent\, paracrine manner. Simultaneously\, by activating AK
 T and S6\, IL-21 accelerates cell cycle progression and the rate of cycle 
 entry of B cells\, increasing their contribution to the ensuing GC. Within
  GC\, IL-21 specifically promotes B cell centroblast identity and\, when b
 ioavailability is high\, plasma cell differentiation. Critically\, these a
 ctions occur irrespective of cognate T:B interactions\, making IL-21 a gen
 eral promoter of growth rather than exclusively mediating affinity-driven 
 selection. I will discuss these findings and their implications for unders
 tanding how GCs balance maintaining a diverse repertoire of reactivities w
 ith selecting cells for high affinity antibody output\, thereby achieving 
 optimal protective immunity. \n\nI am an immunologist with an additional f
 ocus on protein biochemistry and virology. I studied biology in Vienna\, A
 ustria and pursued a PhD at the University of Zürich\, Switzerland. My Ph
 D work provided insights into how small structural changes in antibody-lin
 ked glycans modulate effector functions and the implications this has for 
 antibody-mediated autoimmunity. For my postdoctoral research I joined the 
 laboratory of Prof. David Tarlinton to study the cellular and molecular me
 chanisms regulating the generation and diversification of antibodies. I cu
 rrently hold a position as a senior research fellow and group leader at Mo
 nash University\, Melbourne\, Australia where my research is focused on pr
 oviding the fundamental knowledge required for guiding the magnitude and s
 pecificity of the immune response to vaccination.
LOCATION:Kings Hedges Room\, Babraham Research Campus
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