Immunohistological localization of beta-2-microglobulin in renal tissue as an indicator of renal dysfunction

To elucidate the relationship between localization of beta 2-microglobulin (beta 2-MG) and renal lesions or dysfunction, 119 patients with various renal diseases and various degrees of renal injuries were examined: patients with beta 2-MG deposition (group 1, n = 69), and patients without renal beta 2-MG deposition (group 2, n = 50). beta 2-MG was found mainly in the tubular epithelium and tubular casts. No significant difference in the degree of proteinuria and hematuria were found between the two groups. Group 1 had a significant decrease in glomerular filtration rate (GFR; p less than 0.01): the average values of GFR in group 1 and 2 were 61.1 +/- 35.7 and 95.4 +/- 34.5 ml/min. Group 1 had a significant decrease in the phenolsulfonphthalein excretion test (p less than 0.01) and the maximum urine specific gravity in Fishberg's concentration test (p less than 0.02). Group 1 had a significant high incidence of glomerular sclerotic lesions (p less than 0.001), arteriolar elastosis (p less than 0.01), tubulo-interstitial changes (p less than 0.001) and renal deposition of lysozyme (p less than 0.001). The present study demonstrates that the immunohistological study of renal beta 2-MG deposition is a reliable method to identify renal dysfunction and renal injuries, especially the presence of tubulo-interstitial changes, in various renal diseases.