Transcytosis route mediates rapid delivery of intact antibodies to draining lymph nodes
Laura Kähäri, … , Johanna Ivaska, Marko Salmi
Laura Kähäri, … , Johanna Ivaska, Marko Salmi
Published August 1, 2019; First published June 24, 2019
Citation Information: J Clin Invest. 2019;129(8):3086-3102. https://doi.org/10.1172/JCI125740.
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Research Article Immunology Vascular biology

Transcytosis route mediates rapid delivery of intact antibodies to draining lymph nodes

Abstract

Lymph nodes (LNs) filter lymph to mount effective immune responses. Small soluble lymph-borne molecules from the periphery enter the draining LNs via a reticular conduit system. Intact antibodies and other larger molecules, in contrast, are physically unable to enter the conduits, and they are thought to be transported to the LNs only within migratory DCs after proteolytic degradation. Here, we discovered that lymph-borne antibodies and other large biomolecules enter within seconds into the parenchyma of the draining LN in an intact form. Mechanistically, we found that the uptake of large molecules is a receptor-independent, fluid-phase process that takes place by dynamin-dependent vesicular transcytosis through the lymphatic endothelial cells in the subcapsular sinus of the LN. Physiologically, this pathway mediates a very fast transfer of large protein antigens from the periphery to LN-resident DCs and macrophages. We show that exploitation of the transcytosis system allows enhanced whole-organ imaging and spatially controlled lymphocyte activation by s.c. administered antibodies in vivo. Transcytosis through the floor of the subcapsular sinus thus represents what we believe to be a new physiological and targetable mode of lymph filtering.

Authors

Laura Kähäri, Ruth Fair-Mäkelä, Kaisa Auvinen, Pia Rantakari, Sirpa Jalkanen, Johanna Ivaska, Marko Salmi

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Figure 8

Analyses of the role of endocytosis routes and paracellular permeability in antibody transfer to the draining LNs.

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Analyses of the role of endocytosis routes and paracellular permeability...
(A) Confocal and flow cytometric analyses of draining LNs of WT and Cav1−/− mice after s.c. administration of the indicated fluorochrome-conjugated antibodies (1 μg, t = 5 min, n = 4). The cells were stained ex vivo for CD3 for flow cytometric analysis. Scale bars: 20 μm. (B) Experimental outline for topical application of endocytosis inhibitors (and controls) to surgically exposed LNs. (C–G) Analyses of transcytosis of the indicated s.c. administered fluorochrome-conjugated antibodies (5 μg each, t = 5 min) after topical pretreatment of the draining LNs with (C–F) endocytosis inhibitors or (G) a LEC junctional stabilizer. (C) Pitstop 2 (a clathrin inhibitor) and a Pitstop 2 negative control; (D) monodansylcadaverine (MDC) (a clathrin inhibitor) and vehicle; (E) EIPA (a macropinocytosis inhibitor) and vehicle; (F) imipramine (a macropinocytosis inhibitor) and vehicle; and (G) adrenomedullin and vehicle. The cells were stained ex vivo for CD3. In the bar graphs, each dot represents 1 LN, and data are the mean ± SD. Statistical significance was determined by Mann-Whitney U test.