DETECTION OF TUBULOINTERSTITIAL NEPHRITIS ANTIGEN (TIN-AG) IN LEWIS RAT

Tubulointerstitial nephritis antigen (TIN-ag) is a recently described basement membrane component reactive with autoantibodies in some forms of autoimmune mediated tubulointerstitial nephritis, Immunofluorescen ce studies using polyclonal and monoclonal antibodies have indicated a restrictive tissue distribution for TIN-ag, with the site of most pro minent expression the kidney tubular basement membrane, However, Lewis rat does not demonstrate any immunoreactivity for TIN-ag and does not develop tubuloinsterstitial nephritis after injection of tubular base ment membrane material, As TIN-ag would appear to be a molecule of bio logical significance, experiments were designed to explore the presenc e or absence of this macromolecule in the Lewis rat model, Southern bl otting of Lewis rat genomic DNA revealed the presence of gene sequence s corresponding to TIN-ag, RTPCR analysis of Lewis rat kidney cortex t otal RNA illustrated the expression of a TM-ag gene product, Western b lotting demonstrated the presence of TIN-ag protein forms in kidney co rtical homogenates of Lewis rat, The data suggest either extensive epi tope masking or expression polymorphism of TIN-ag in the Lewis rat.