Addition of fetal LTic is sufficient to rescue the impaired formation of lymphoid aggregates by E15 iLN upon kidney graft. (A) Forward- and side-scatter profiles of a host iLN, a reaggregate E15 iLN, and an E15 iLN that receive LTic's were grafted under the kidney capsule of adult recipients and analyzed for their cellular content 2 weeks after transplantation. Reaggregated E15 iLNs formed a mass of dead cells, while the reaggregated E15 iLNs that receive LTic's contained live cells. (B) Reaggregated E15 iLN + LTic contained T and B cells. Numbers above brackets correspond to percentages of CD19⁺ B cells. Percentages of single positive CD4, CD8 and CD4⁻8⁻ are shown in each quadrant of dot plots. (C) B and T cells in reaggregated iLNs were organized in specific areas similar to adult LNs as seen by immunofluorescence staining with anti-CD3 (blue) and anti-B220 (red) mAbs (10x). (D,E) HEV development in reaggregate iLNs. Reaggregated E15 iLN + LTic structures contain a network of HEVs. Immunofluorescence staining of sections of E15 iLN + LTic reaggregated LN grafts with MECA 79 mAb (red) that recognizes a sugar moiety present in several peripheral node addressins (PNAd's) that are expressed in HEVs. The white rectangle in panel D (25×/1.4 NA) is enlarged in panel E (40×/1.4 NA water lens). Results shown are representative of 6 independent assays.