DETAILED ANALYSIS OF PHENOTYPES OF MACROPHAGES INFILTRATING GLOMERULIIN RAT ANTI-THY1 NEPHRITIS

A phenotypic analysis of infiltrating macrophages in rat anti-Thy 1 gl omerulonephritis induced by monoclonal antibody(mAb) 1-22-3 was carrie d out using recently reported macrophage-specific mAbs. This was combi ned with a more detailed quantitative analysis, counting positive cell s in isolated glomeruli, to obtain more information on the roles playe d by macrophages in glomerulonephritis, In normal glomeruli a small nu mber of ED1- or OX-3(anti-Ia)-positive cells but almost no ED2-, TRPM- 3- or Mar-3-positive cells were observed. EDI-positive cells increased from 2 h and peaked between days 3 and 7 after mAb injection. TRPM-3- positive cells increased from day 3 and peaked on day 7, later than ED 1. The numbers of OX-3-positive cells changed in parallel with those o f ED 1-positive cells. Mar-3, which stained blood monocytes and ED2, w hich is an indicator of tissue-fixed resident macrophages, did not rea ct with glomerular infiltrating macrophages. In a double staining stud y, about 40% of ED1- or OX-3-positive cells costained with TRPM-3 on d ay 3 and the percentage increased on day 7, but hardly any cells were positive for TRPM-3 alone, This results in two different phenotypes (E D1(+),ED2(-),OX-3(+),Mar-3(-), TRPM-3- and ED1(+),ED2(-),OX-3(+),Mar-3 (-),TRPM-3(+)) of infiltrating macrophages. We conclude that in rat an ti-Thy1 glomerulonephritis, monocytes/ macrophages may infiltrate the mesangium, rapidly changing their phenotype (Mar-3(+) to Mar-3(-)) and resulting in a gradual shift to TRPM-3-positive, activated macrophage s.