Impairment of renal function in various types of glomerular disease is associated with tubulointerstitial changes. The mechanism of mononuclear cell infiltration in the interstitium is not fully understood. Recently, monocyte chemoattractant protein-1 (MCP-1) has been identified as a monocyte-specific chemotactic factor. We analyzed the presence of MCP-1 in renal biopsies from patients with various forms of glomerular disease and demonstrated that MCP-1 expression is increased in renal tubular epithelial cells during disease. Further analysis showed that various cell lines of human proximal tubular epithelial cells (PTEC) produce MCP-1 in culture under serum-free conditions and that the production is inhibited by cycloheximide. IL-1 alpha and TNF-alpha enhanced the production by each cell line in a dose- and time-dependent manner as measured by radioimmunoassay. Northern blot analysis demonstrated that IL-1 alpha and TNF-alpha markedly enhanced the expression of MCP-1 mRNA. Taken together these observations support the notion that MCP-1 is synthesized de novo by PTEC. MCP-1 produced by PTEC is found to be 13 kD by gel filtration chromatography. It is chemotactically active for monocytes. We conclude that in various types of glomerular disease, MCP-1 expression in tubular epithelial cells is associated with up-regulation of MCP-1 production by PTEC. These findings raise the possibility that macrophages may accumulate in renal interstitium as a consequence of MCP-1 production by PTEC.

In 14 ADPKD patients the total body clearance and the urinary clearance of inulin using the constant infusion method were compared with the "single-shot" technique. Triplicate measurements of both clearances by each infusion method were obtained in 12 out of 14 patients. A high correlation was found between the total body clearance and the urinary clearance for both the constant infusion method (r = 0.96) and the single injection technique (r = 0.96). The coefficient of variation for the total body clearance of inulin was significantly lower for the constant infusion method and the single injection technique (7.8% and 7.1%) than for the urinary clearance of inulin (11.3% vs. 9.7%, P < 0.05). A constant overestimation of the urinary clearance by the total body clearance was observed with both methods (constant infusion method 8.3 ml.min-1 x 1.73 m-2 and single injection technique 13.4 ml.min-1 x 1.73 m-2). No concentration-dependent clearance was present. Determination of plasma inulin, especially at low levels, showed substantial interference by glucose. We conclude that, taking into account a constant overestimate of urinary clearance by the total body clearance of inulin, the single injection total body clearance possesses the best reproducibility and shows a good agreement with the conventional urinary clearance, which can be calculated by: GFR = TBCLss-13.1 ml.min-1 x 1.73 m-2 (in the range of 28 to 124 ml.min-1 x 1.73 m-2).

SUMMARYA number of inflammatory kidney diseases are associated with interstitial nephritis and influx of leucocytes in the renal interstitium. Potentially the influx of neutrophils in the interstitium may be induced by the chemotactic cytokine IL-8. In the present study we have analysed the production of IL-8 by cultured human proximal tubular epithelial cells (PTEC) in response to a number of proinflammatory cytokines. Primary cell lines of proximal tubular epithelium obtained from ten different kidneys, and cultured under serum-free conditions, were found to produce IL-8 to different degrees from not detectable levels up to 10

The present study showed a high prevalence of CKD in representative urban and semi-urban areas and argues for screening and treatment of all Indonesians, particularly those at an increased risk of CKD.

These data suggest that urinary excretion of MCP-1 can be used as a marker for the episodes of acute rejection. The increase of urinary excretion of MCP-1 most likely is the result of local production by tubular epithelia cells. MCP-1 produced locally may, at least in part, be responsible for the influx of macrophages into the interstitium during rejection.