IMMUNOCYTOCHEMICAL LOCALIZATION OF TAMM-HORSFALL PROTEIN IN THE KIDNEYS OF NORMAL AND NEPHROLITHIC RAT

Studies using in vitro systems have indicated that Tamm-Horsfall prote in (THP) can Interact with calcium oxalate (CaOx) crystals during kidn ey stone formation. However, information regarding the nature of its p articipation in this process remains controversial and unclear. In ord er to better understand the putative interaction of THP and crystals i n vivo, we compared the localization of THP in normal rats and in chro nic and semi-acute rat models of nephrolithiasis. In these rats, CaOx crystal deposits were induced in the kidneys by administering ethylene glycol (EG) in drinking water. The formation of CaOx mono- and dihydra te aggregates in the urine was confirmed by scanning electron microsco py. Immunohistochemical localization, as well as protein A-gold labeli ng at the ultrastructural level, demonstrated that in addition to its normal distribution, THP specifically associated with the renal crysta l deposits. The THP-containing, organic matrix-like material consisted of a fine, fibrillar meshwork surrounding individual crystals and the ir aggregates. In addition, THP also appeared in the papilla, where it is normally absent, concurrent with the appearance of crystal deposit s in the kidneys. These observations indicate that in nephrolithic rat s the normal localization of THP is altered. Such an alteration may in dicate an important physiological event related to crystal aggregation and kidney stone formation.