Fig. 1: Antigen levels in lymph node stromal cells after immunization.

a Experimental schematic for b–e. C57/BL6 mice were immunized subcutaneously in the footpad and/or flank with the indicated antigens and adjuvants. b Cells were stained with CD45, PDPN, CD31 and PD-L1. Cells were gated on CD45-PDPN + CD31- for FRC and CD45-PDPN + CD31+ for LECs. Shown are examples of LEC and FRC antigen-positive cells based on PD-L1 expression (floor, MARCO LEC) and ova-AF488+ from mice 2–3 weeks after immunization with ova conjugated to Alexa-Fluor 488 (AF488) and polyI:C and αCD40. c Quantification of the frequency of LEC, BEC, and FRC in the popliteal lymph node (pLN) that are positive for the indicated antigens administered with polyI:C and αCD40 at indicated time. d Same as (b) except for mice were immunized with SARS-CoV-2-RBD-AF488, polyI:C, and αCD40. e Same as in (c) except for SARS-CoV-2-RBD and CHIKV-E2 with polyI:C and αCD40. CHIKV-E2 was repeated for 9–14 days post-vaccine (~2 weeks). Statistical analysis was done using an unpaired t-test where the p-value between naïve and indicated antigen is <0.0001. In each experiment, at least n = 2–3 mice per group were evaluated and the experiment was repeated n = 2–5 times for c–e. Shown is the representative data from one of the experiments. Error bars are mean ± standard error of the mean. ns not significant, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.