Clonal Expansion under the Microscope: Imaging Collective T Cell Responses with Single Cell Resolution
Michal Polonsky1, Jacob Rimer1, Ira Zaretsky1, Keren Levinstein Hallak1, Amos Kern-Perets1, Chamutal Borenstein1, Eyal David1, Naama Kopelman2, Ziv Porat2, Benjamin Chain3, Nir Friedman1*
1)Department of Immunology, Weizmann Institute of Science, Rehovot, Israel.
2)Bioinformatics and Biological Computing Unit, Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel.
3)Division of Infection and Immunity, University College London, London, UK
Clonal expansion of lymphocytes is a hallmark of vertebrate adaptive immunity. Precursor cells that recognize a specific antigen proliferate into expanded clones, differentiate and acquire various effector and memory phenotypes which promote effective immune responses. Recent studies establish a large degree of heterogeneity in the level of expansion and in cell state between and within expanding clones.
Live cell imaging of ex vivo cultures within micro fabricated arrays provides an attractive methodology for studying clonal expansion. These experiments facilitate continuous acquisition of a large number of parameters on cell number, proliferation, death and differentiation state, with single cell resolution on thousands of expanding clones that grow within controlled environments.
Using live cell imaging of primary T cells in microwell arrays, we reveal stochastic and instructive mechanisms that contribute to observed heterogeneity and elucidate the temporal dynamics of differentiation events. We use this system to study collective processes affecting the differentiation of naïve CD4 T cells into T memory precursors. We found that differentiation of precursor memory T cells is driven by local intercellular interactions, revealing new mechanisms of social T cell behavior.
Funding: This research was supported by grants from the Israel Science Foundation (grant no. 1184/15), and the Ministry of Science, Technology and Space of the State of Israel and the German Cancer Research Center (DKFZ).