TUBULOINTERSTITIAL NEPHRITIS ANTIGEN INTERACTS WITH LAMININ AND TYPE-IV COLLAGEN AND PROMOTES CELL-ADHESION

Tubulointerstitial nephritis (TIN) antigen has been recently identifie d as a novel basement membrane macromolecule. It consists of a single chain of 58 kDa and exhibits a restricted distribution. The interactio n between TIN antigen and laminin or type IV collagen has been studied using solid-phase binding assays and found to be for both macromolecu les specific, saturable, and with an affinity in the low micromolar ra nge. In similar assays, TIN antigen did not interact with heparin. In turbidimetry assays, it was found that the presence of TIN antigen did not affect the polymerization of type IV collagen but had a concentra tion-dependent inhibitory effect on laminin polymerization and on pref ormed laminin polymers. TIN antigen was able to promote adhesion of ep ithelial cells derived from kidney tubules and of endothelial cells de rived from aorta. The data suggest that TIN antigen may be a macromole cule of importance both for basement membrane ultrastructure and cellu lar adhesion.