Year: 2019
Type: dissertation
Abstract: The production of antibodies, with their potential to recognise unique targets and prevent repeat infections, is an important aspect of immune health.In order to generate free antibodies, the cells responsible, B cells, must undergo a differentiation step to transform from lymphoblast to antibody secreting cell (ASC).This differentiation step prevents further antibody modifications and hence the timing for optimal immunity requires a delicate balance between expanding useful clones and providing early protection.How differentiation is controlled to achieve this balance for an effective immune response is of great interest.In this study, the progression from naïve B cells to ASC was investigated in the context of an emerging model for competing cell fates.By this model, alternate cell fates, such as division, death and differentiation, are pursued independently in individual cells but are in competition such that events which occur earlier prevent those that require more time from being observed.Evaluation and testing of this model requires careful measurement of distributions of times to fates which is only possible with single cell fate tracking.Here I have developed and applied methods for live cell imaging and analysis for assessing and evaluating cell fate changes over time.Using these methods, several modes of regulating differentiation times were revealed.Low levels of stimulation through CD40 produced a greater proportion of antibody secreting cells per generation as division is slowed and more time is allowed for differentiation, consistent with competing cell fates.A second mechanism was found where increasing division numbers directly reduced the amount of time required for cells to differentiate, without modulating division times, ensuring the natural development of ASC during the ongoing immune response.A direct method of uncensoring was explored where cell cycle inhibitors were used to prevent division, with the hypothesis that more cells would go on to differentiate in the absence of competition.Various inhibitors were assessed for their suitability to this task, and a panel of compounds were found to be suitable for uncensoring underlying differentiation and cell death times.Findings from this study are consistent with the model of independent and competing cell fates, and significantly advance our understanding of how antibody responses are controlled and can be modelled at the cell population level.First and foremost, I would like to thank Phil for giving me the opportunity to work on this project.Bridging my love for biology and comfort with mathematics was not something I had given much thought to as a naïve graduate, but upon meeting the lab, was overwhelmed with a sense of belonging.I may not have been the perfect student, but your support, patience, kindness and guidance were exactly what I needed to grow, and I am forever grateful.Lynn -for always looking out for me, showing me how to be strong and sometimes asking the hard questions.Between you and Phil, I could not have asked for better role models.DT -for your pespective, wit, and down-to-earth nature.Steve -for your insights, but also for sharing your love of the wilderness and artisan food.Edwin -for all your help and constructive conversations.I feel extremely privileged to have been watched over by you all, and even if a little of your brilliance, wisdom, generosity, and scientific integrity rubs off on me, I'd be happy.Su -for your care, kindness, patience, and advice.Julia -for being my student buddy.The two of you were there for celebrations, commiserations, tears of grief, fear, joy and frustrations; with lots of delicious cake, many, many biscuits, cups of tea, and drinks at the pub in between.Thank you both for joining me on the ride (and for the scientific advice, of course).Kim, Andrey, Mark, John, Cam -it was delightful working with you, and I have learned so much from each and every one of you.Ken -for the insight, fresh perspectives, laughs, and overnight turnarounds when required!Kim -for keeping everything running
Author: Jie Zhou
Language: English
Topic: T-cell and B-cell Immunology
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3033102439