Uncovering immune network principles driving humoral immunity in inflammatory conditions

B cells participate in germinal center (GC) reactions to generate high-affinity antibodies which represent a crucialline of protection from viruses and other pathogens. To date the mechanism by which the highest-affinity B cellclones are selected remains elusive. Vital to the development of these high-affinity clones are T follicular helper(Tfh) cells which stimulate B cells to undergo GC selection through an interaction known as T cell help. Whileour understanding of T cell help dynamics in single-antigen GCs has significantly increased over the last fewyears less is understood about the distribution of Tfh cell help in inflammatory conditions such as viral infectionsor cancer. Importantly GC-like clusters referred to as tertiary lymphoid structures (TLSs) have been a subject ofrecent interest as chronic respiratory viral infections and many cancers and are accompanied by TLS formation.Notably the occurrence of TLSs in cancer patients correlates with some exceptions - with increasedresponsiveness to immunotherapy. However most studies are limited to describing the appearance of TLS andhow their formation is correlated with patient outcome rather than providing mechanistic details about their anti-tumoral effects.The F99 phase of this proposal is focused on determining how T cell help varies and is distributed amongdifferent viral protein-specific B cell clones co-residing in GCs and TLSs using intercellular labeling and in vivoinfection models. Having established novel methods to study immune networks in lymph nodes and virus-induced TLSs in lungs of Influenza A virus infected mice I am characterizing the properties and directionality inwhich T cell help is provided to B cells of varying antigen-specificities and investigating how competition for Tcell help shapes the antibody repertoire against Influenza A virus.For the K00 phase of this proposal I plan to leverage my experiences using mechanistic mouse models of B-and T-cell collaboration with my prior work studying cancer immunology to elucidate the dynamics of TLScontribution to humoral immunity in vivo with a focus on lung adenocarcinoma models. By characterizing thecontacts between immune cells taking place in cancer-induced TLSs I hope to uncover the pathways in tumor-bearing mice that generate beneficial TLSs. Applying my expertise with intercellular labeling approaches andtissue multi-photon microscopy I aim to identify if and how the immune cell interaction landscape changes in thecontext of immunotherapy. These insights could then be used to develop ways to reprogram inert TLSs orproduce new TLSs that are capable of tumor control.