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 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 3

Fc tail– and Fc receptor–independent uptake of lymph-borne antibodies in draining LNs.

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Fc tail– and Fc receptor–independent uptake of lymph-borne antibodies in...
(A) mRNA expression of Fc receptors in LECs and BECs in peripheral LNs (from Immunological Genome Project Data; https://www.immgen.org/). Values (mean) above 120 (red dashed line) indicate positivity with 95% confidence. (B) Flow cytometric analyses of lymphocytes in the draining LNs of WT and FcRn−/− mice after s.c. administration of the indicated fluorochrome-conjugated B220 and CD4 antibodies (1-μg dose, t = 5 min, n = 8). The cells were stained ex vivo for CD3. (C) Flow cytometric analyses of lymphocytes in the draining and nondraining LNs of WT mice after s.c. administration of chicken IgY (Alexa Fluor 647–conjugated IgY antibody against mouse IgG [IgG-A647]; 2 μg, t = 5 min, n = 3). The cells were stained ex vivo for B220. (D) Flow cytometric analyses of lymphocytes in the draining LNs of WT mice after s.c. administration of whole Ig and (Fab)2 fragments of the L-selectin antibody MEL-14 (2 μg, t = 30 min, n = 3). The cells were stained ex vivo with Alexa Fluor 488–conjugated anti–rat IgG and for B220 and CD4. (E) Analyses of lymphocytes in the draining LNs of WT mice after s.c. administration of the indicated fluorochrome-conjugated B220 and CD4 antibodies (2 μg, t = 5 min, n = 4) in the presence of a 100-fold excess of unlabeled polyclonal mouse IgG (mIgG) or vehicle control. The cells were stained ex vivo for CD3. In the bar graphs, each dot represents 1 LN, and data are the mean ± SD. *P < 0.05, by Mann-Whitney U test.