Abstract for presentation at Australia and New Zealand Society of Nephrology Annual Scientific Conference

In vivo antigen-specific T cell responses are difficult to study due to low frequencies of antigen-specific cells. CFSE-labeled ovalbumin (OVA)-specific TcR transgenic (OT-II) cells were transferred to C57BL/6 mice. CD4+ cell proliferation (serial halving of CFSE fluorescence) in draining lymph nodes (DLN) was studied 36h and 72h after intrarenal OVA injection and compared with subcutaneous injection. After subcutaneous OVA, OT-II cells were dividing (DLN: 36h 2-3 cycles); at 72h, division progressed (peak >7 cycles). In contrast, 36h after intrarenal antigen OT-II cells had not divided. By 72h proliferation was observed (peak 4 cycles). To address why antigen-specific activation is delayed in the renal DLN, the phenotype of renal dendritic cells (DCs, CD11c+) was studied. Compared with splenic DCs, renal DCs had lower CD11c expression, but similar proportions of CD11c+ cells expressed CD11b and MHCII. Most renal DCs were F4/80+ (linked with tolerogenic signals: 80±3 vs 19±0.1% [splenic]). To study DCs with antigen, FITC-OVA was injected intrarenally/subcutaneously and the phenotype of FITC+CD11c+ cells in DLN were compared at 4h, 18h or 30h. At each timepoint, antigen positive renal DLN DCs proportions were less numerous and contained less OVA-FITC. Despite the high proportion of F4/80+ DCs in the kidney, only a minority of FITC-OVA+ DCs in renal DLNs were F4/80+ (Table). These studies demonstrate that after antigen stimulation CD4+ cell proliferation to renal antigens lags behind dermal antigens; fewer DCs bearing less antigen arrive in the renal DLN; there is a significant proportion of renal F4/80+ DCs not present in the DLN.