LOCALIZATION OF RENAL ERYTHROPOIETIN AND THE ROLE OF IA-ANTIGEN EXPRESSION IN HYPOXIC RAT GLOMERULI

Erythropoietin (EPO) producing cells were examined by the immunofluorescent antibody technique, and the alterations in the Ia antigen expression in glomeruli by hypoxic stimuli. Antisera were obtained from rabbits immunized with pure human EPO. Positive fluorescence was localized in glomerular mesangial regions of the hypoxic rat kidney. Although hypoxia showed neither increase in the number of glomerular cells nor hypertrophy of the mesangial matrix, it induced an increase of the Ia antigen expressions in glomeruli. The peak of the increase occurred 2 hr after hypoxia and then decreased until 24 hr later. The increase of Ia antigen after 2 hr of hypoxic stimuli was 176.5±7.0% of normal controls, and ranged from 151 to 209%. In conclusion, Ia positive cells in glomeruli may have some relationship to the stimulation of EPO production.