PT - JOURNAL ARTICLE AU - Rob C. Oslund AU - Tamara Reyes-Robles AU - Cory H. White AU - Jake H. Tomlinson AU - Kelly A. Crotty AU - Edward P. Bowman AU - Dan Chang AU - Vanessa M. Peterson AU - Lixia Li AU - Silvia Frutos AU - Miquel Vila-Perelló AU - David Vlerick AU - Karen Cromie AU - David H. Perlman AU - Samantha D. O’Hara AU - Lee R. Roberts AU - Grazia Piizzi AU - Erik C. Hett AU - Daria J. Hazuda AU - Olugbeminiyi O. Fadeyi TI - Detection of Cell-Cell Interactions via Photocatalytic Cell Tagging AID - 10.1101/2021.10.04.463039 DP - 2021 Jan 01 TA - bioRxiv PG - 2021.10.04.463039 4099 - http://biorxiv.org/content/early/2021/10/04/2021.10.04.463039.short 4100 - http://biorxiv.org/content/early/2021/10/04/2021.10.04.463039.full AB - Cell-cell interactions drive essential biological processes critical to cell and tissue development, function, pathology, and disease outcome. The growing appreciation of immune cell interactions within disease environments has led to significant efforts to develop protein- and cell-based therapeutic strategies. A better understanding of these cell-cell interactions will enable the development of effective immunotherapies. However, characterizing these complex cellular interactions at molecular resolution in their native biological contexts remains challenging. To address this, we introduce photocatalytic cell tagging (PhoTag), a modality agnostic platform for profiling cell-cell interactions. Using photoactivatable flavin-based cofactors, we generate phenoxy radical tags for targeted labeling at the cell surface. Through various targeting modalities (e.g. MHC-Multimer, antibody, single domain antibody (VHH)) we deliver a flavin photocatalyst for cell tagging within monoculture, co-culture, and peripheral blood mononuclear cells. PhoTag enables highly selective tagging of the immune synapse between an immune cell and an antigen-presenting cell through targeted labeling at the cell-cell junction. This allowed for the ability to profile gene expression-level differences between interacting and bystander cell populations. Given the modality agnostic and spatio-temporal nature of PhoTag, we envision its broad utilization to detect and profile intercellular interactions within an immune synapse and other confined cellular regions for any biological system.Competing Interest StatementR.C.O., T.R.R., C.H.W., J.H.T., K.A.C., D.H.P., S.D.O., L.R.R., G.P., L.L., D.C., V.M.P., E.P.B., E.C.H., D.J.H., and O.O.F. were employed by Merck & Co., S.F., and M.V.-P. were employed by SpliceBio S.L., D.V. and K.C. were employed by Ablynx Inc. during the experimental planning, execution and/or preparation of this manuscript.