The precise pathways of memory T-cell differentiation are incompletely understood. Here we exploit transgenic mice expressing fluorescent cell cycle indicators to longitudinally track the division dynamics of individual CD8+ T cells. During influenza virus infection in vivo, naive T cells enter a CD62Lintermediate state of fast proliferation, which continues for at least nine generations. At the peak of the anti-viral immune response, a subpopulation of these cells markedly reduces their cycling speed and acquires a CD62Lhi central memory cell phenotype. Construction of T-cell family division trees in vitro reveals two patterns of proliferation dynamics. While cells initially divide rapidly with moderate stochastic variations of cycling times after each generation, a slow-cycling subpopulation displaying a CD62Lhi memory phenotype appears after eight divisions. Phenotype and cell cycle duration are inherited by the progeny of slow cyclers. We propose that memory precursors cell-intrinsically modulate their proliferative activity to diversify differentiation pathways.

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Portal tracts are key intrahepatic structures where leukocytes accumulate during immune responses. They contain the blood inflow, which includes portal blood from the gut, and lymphatic and biliary outflow of the liver, and as such represent a key interface for potential pathogen entry to the liver. Myeloid cells residing in the interstitium of the portal tract might play an important role in the surveillance or prevention of pathogen dissemination; however, the exact composition and localization of this population has not been explored fully. Our in-depth characterization of portal tract myeloid cells revealed that in addition to T lymphocytes, portal tracts contain a heterogeneous population of MHCII high myeloid cells with potential antigen presenting cell (APC) function. These include a previously unreported subset of CSF1R-dependent CX3CR1 + macrophages that phenotypically and morphologically resemble liver capsular macrophages, as well as the two main dendritic cell subsets (cDC1 and cDC2). These cells are not randomly distributed, but each subset forms interconnected networks intertwined with specific components of the portal tract. The CX3CR1 + cells were preferentially detected along the outer border of the portal tracts, and also in the portal interstitium adjacent to the portal vein, bile duct, lymphatic vessels and hepatic artery. cDC1s abounded along the lymphatic vessels, while cDC2s mostly surrounded the biliary tree. The specific distributions of these discrete subsets predict that they may serve distinct functions in this compartment. Overall, our findings suggest that portal tracts and their embedded cellular networks of myeloid cells form a distinctive lymphoid compartment in the liver that has the potential to orchestrate immune responses in this organ.

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Fo Guang Shan (FGS), a transnational Buddhist movement in the Chinese Mahāyāna tradition, has grown rapidly in the last fifty years to become a global network of close to 180 branch temples. For almost thirty years, FGS Oceania has invested heavily in the Buddha’s Birthday Festival annually in the form of weekend-long festivals in public spaces across Australia and New Zealand, involving months of planning and thousands of volunteers to welcome tens of thousands of visitors. FGS Oceania served as an incubator, exporter, and importer of innovations to make the Buddha, Dharma, and Sangha accessible to the public through these festivals. Here, we map the flows of such innovations among the headquarters in Taiwan, the Oceanic branches, and other regional headquarters to examine the dynamics of organisational learning that drive these innovations. Using a system of systems model, we argue that such flows were enabled by FGS’ culture of innovation and the independent yet collaborative nature of its transregional network.