MACROPHAGIC CELLS OUTGROWTH FROM NORMAL RAT GLOMERULAR CULTURE - POSSIBLE METAPLASTIC CHANGE FROM PODOCYTES

One representative of a number of severe lesions that occur outside th e glomerular capillaries and involve podocytes is crescentic glomerulo nephritis. The question of whether the crescent-forming cells are deri ved from glomerular epithelial cells or monocytes/macrophages is highl y controversial and has not yet been clarified. To investigate the pat hophysiology of podocytes in crescentic glomerulonephritis, we attempt ed to establish methods for culturing cells confirmed to be derived fr om podocytes, focusing particularly on the relationship between podocy tes and macrophages. Nonadherent cells of unknown origin that grew fro m normal rat isolated glomerular cultures increased in number, reachin g a total of 3.5 x 10(5)/ml on Day 11. They showed several characteris tics of macrophages, the expression of specific antigens and enzymes, morphology, and production of H2O2. They expressed Fx1A but lacked the expressions of Thy1.1 or factor VIII. A morphologic kinetic study on Days 3 to 11 of culture showed that the cells with foot processes on t he glomerular basement membrane changed into macrophagic cells (MC) an d migrated from the glomeruli. Immunofluorescence double staining indi cated that the cells that migrated from the glomerular surface on Day 8 were both anti-podocalyxin- and ED-1-positive. Furthermore, immunoel ectron microscopy revealed that the ED-1-positive cells were located o n the glomerular basement membrane. Pretreatment with anti-macrophages and -Thy1.1 antibodies, both with complement, did not reduce the numb er of MC, whereas pretreatment with puromycin aminonucleoside predomin antly reduced the number of MC. A predominant decrease in the number o f glomerular macrophages by gamma-irradiation did not result in a redu ction of the number of MC. MC derived from glomerular cultures of bone marrow chimeric rats expressed the la antigen originated from recipie nt, which indicates that MC is not derived from bone marrow cells. Mac rophage colony-stimulating factor accelerated the speed of the change into MC, and granulocyte-macrophage colony-stimulating factor dramatic ally enhanced its degree with increase of cell number on Day 8. We con cluded that podocytes change into MC in normal rat glomerular culture and that the change is enhanced by colony-stimulating factors. The res ults provide a completely new insight into the origin of crescent-form ing cells.