Figure 6.

Podocytes activate naive T cells in vivo. (A) The schematic drawing illustrates the experimental setup. Transgenic mice expressing ovalbumin exclusively in the podocytes were radiated, and the hematopoietic system was reconstituted with bone marrow from B6.C.H2^bm1 mice. These transferred hematopoietic cells are unable to present the ovalbumin peptide SIINFEKL. After complete reconstitution, anti-glomerular basement membrane (αGM) nephritis was induced by preimmunization with rabbit IgG in complete Freund's adjuvant (rb IgG + CFA) followed by two injections of a rabbit serum (αGM) reacting against murine glomerular basal membrane. The time course is shown in B. After 18 days, with the onset of proteinuria, CFSE-labeled OT-I cells were injected intravenously to monitor ovalbumin presentation by the proliferation of the transferred transgenic T cells. (C) Analysis of spleen cells indicating the success of the bone marrow transplantation. Only transferred CFSE-labeled OT-I cells are 5F1-positive, because this antibody does not recognize the H2^bm1 antigen. A representative experiment displaying cells of two mice is shown in D for spleen and E for renal lymph nodes. The gates were set on the transgene T cell receptor Vα2. Please note that a T cell proliferation was only detectable in nephrin-OVA transgenic mice, whereas cells of C57BL/6 mice remained negative. The summary of several experiments is shown in F. *P<0.05. Bone marrow DCs from the same mice were generated and incubated with 0.5 mg/ml ovalbumin and incubated with OT-I or OT-II cells. (G) The proliferation was measured by ³H thymidin uptake. Bone marrow DCs from bone marrow chimeric mice did not activate OT-I cells but activated CD4+ transgenic OT-II T cells, showing that MHC class II presentation was not altered in the animals and that bone marrow reconstitutions were complete.