POLYLACTOSAMINE SUGAR CHAINS EXPRESSED BY EPITHELIA OF HENLES LOOP AND COLLECTING DUCT IN RAT AND HUMAN KIDNEY ARE SELECTIVELY RECOGNIZED BY HUMAN COLD AGGLUTININS ANTI-I I/

Normal rat and human kidney was mapped immunohistochemically with huma n monoclonal cold agglutinins against the biochemically related erythr ocyte glycoconjugate antigens I and i, which represent branched and li near polylactosamines, respectively. The antibodies worked well with b oth cryostat and paraffin-embedded material. Anti-i gave specific stai ning of collecting duct cells (mostly principal cells) as evidenced by double labelling with antibodies to band 3 and a 23 kD protein of int ercalated cells. In contrast, anti-I turned out to be the first exclus ive marker for the ascending and descending thin limb of Henle's loop. In addition, in rat kidney, the binding of anti-I/i was preserved in primary cultures both of principal cells of the papillary collecting d uct and cells of the thin limb of Henle's loop. Our results suggest th at both antibodies might be interesting tools for in vitro studies of renal cell physiology and the investigation of kidney development.