DISTRIBUTION OF PODOCYTE PROTEIN (44 KD) IN DIFFERENT TYPES OF GLOMERULAR-DISEASES

The podocyte protein, 44 KD (pp44), is a podocyte-specific antigen tha t is selectively distributed in the cytoplasm of foot processes. It ha s been suggested that the pp44 antigen is associated with the cytoskel eton and helps to maintain the complex architecture of podocytes. To a nswer the question as to whether changes in pp44 expression are associ ated with changes in podocyte morphology, we investigated the distribu tion of the pp44 antigen in different kidney diseases. Twenty-one kidn ey biopsies and one nephrectomy specimen were studied by indirect immm unofluorescent technique and electron microscopy. The pp44-antigen is preserved in cases associated with foot process fusion. In contrast, t he antigen could not be detected in areas of capillary wall necrosis, cellular crescents or early and advanced stages of focal segmental glo merulosclerosis - even in the presence of podocytes. Our results show that the pp44 antigen is preserved in diseases associated with reversi ble loss of foot processes (in cases with foot process fusion associat ed with proteinuria). In contrast, the pp44 antigen is not detectable in the area of FSGS and cellular crescents, suggesting that in these c onditions, podocytes undergo irreversible injury even if they are stil l present on conventional light microscopy.