Cultured PTC clearly expressed intercellular adhesion molecule-1 (ICAM-1) under the influence of tubular basement membrane antigen (TBM)-primed lymphocytes. These TBM-primed lymphocytes also demonstrated a high cytotoxic activity against cultured PTC. A pure preparation of isolated PTC from BALB/c mouse kidney was brought into primary culture. PTC was prepared by the method of Boogaard PJ et al, and our modification. Briefly, kidney was perfused with buffer containing 0.08% (w/v) collagenase. The cortical tissue was then filtered through nylon-gauze. Viable PTC were separated from other materials by isopycnic centrifugation on a discontinuous Nycodenz gradient. The confluent monolayer of PTC showed a typical epithelial morphology with cobblestone-like cells in the center of the cell-islands. Typical dome formation was observed in PTC cultures. These cells also strongly expressed gamma-glutamyl transpeptitase activity. Coculture of PTC with syngeneic lymphocytes primed with TBM antigen induced ICAM-1 expression in PTC. The TBM-primed lymphocytes had a cytotoxic activity without complement. However, neither virgin lymphocytes nor liver antigen-primed lymphocytes had cytotoxic activity. This simple syngeneic experimental model may allow us further molecular biological examination of renal tubulointerstitial diseases.