SIALIC-ACID EXPRESSION IN NORMAL AND DISEASED HUMAN KIDNEY

Three-sialic acid-specific lectins, Tritrichomonas mobilensis (TML) (w ithout linkage preference), Maackia amurensis leukoagglutinin (MAL) (a lpha 2, 3) and Sambucus nigra agglutinin (alpha 2,6 linkage-specific), were used for detection of sialylated glycoconjugates in normal and d iseased human kidneys. Normal kidneys demonstrated strong podocyte pos itivity of alpha 2,3 linked sialic acid and weaker sialic acid express ion on capillary endothelium, which was alpha 2,6 linked. Renal biopsi es (45) representing a variety of diseases, e.g. minimal change diseas e, membranous, membranoproliferative glomerulonephritis, tubulointerst itial nephrosis or diabetic glomerulopathy showed increased sialic aci d expression in glomerular capillaries, Bowman's capsule epithelium an d on podocytes. In several different kidney diseases the glomerular en dothelium expressed also alpha 2,3 linked sialic acid along with incre ased TML-positivity of epithelial cells related to alpha 2,6 linked si alic acid. No-difference in sialic acid linkage expression was observe d in the tubules, which expressed putative alpha 2,6 linked sialic aci d on the luminal surface of cells distal to the descending limb of Hen le's loop. The study did not show changes characteristic of specific d iseases. Rather, increased sialic acid expression on glomerular endoth elium and podocytes was linked to a variety of pathological changes. I t is assumed that changes in sialysation of glycoconjugates in the glo meruli represent nonspecific changes and do not reflect fundamental pa thogenetic features of renal diseases.