Polylactosamine sugar chains expressed by epithelia of Henle's loop and collecting duct in rat and human kidney are selectively recognized by human cold agglutinins anti-I/i

Identification of nucleated cells in urine using lectin staining

Microscopic examination of urinary sediment is an integral component in the evaluation of nephropathies. However, identification and differentiation of the nucleated nonsquamous cells in urine is often difficult using such conventional techniques as phase contrast or bright field microscopy, even after Papanicolaou staining, and requires a lot of experience. We now report a method to differentiate urinary cell types using lectin staining. Twenty-five lectins were examined with respect to their binding pattern on cryosections of the human kidney and urinary tract, as well as binding to blood cells. The specificity of lectin binding to a cell type both in situ and in urine was confirmed by double labeling with specific antibodies directed against various sections of the nephron or nucleated blood cells. For urine cytologic examinations, acetone-fixed cytopreparations of urinary sediments were incubated with a combination of a fluorescein isothiocyanate (FITC)-coupled and a rhodamine-coupled lectin, followed by staining of the nuclei with 4',6-diamidino-2-phenylindole. Specimens were examined in triple immunofluorescence (FITC/rhodamine/UV). Cell types could be identified by their characteristic lectin-binding pattern. For example, the lectin combination of Sophora japonica agglutinin (aggl; SJA) and Erythrina cristagalli aggl (ECA) permitted a differentiation between cells of the proximal tubules (SJA positive [SJA+], ECA+), distal tubules (SJA negative [SJA-], ECA+), collecting ducts (SJA+, ECA-), and lymphocytes (SJA-, ECA-). In preliminary studies, examination of urinary sediment in various chronic nephropathies by this technique showed differences in their cellular excretion pattern. In summary, staining urinary sediments with combinations of lectins provides a rapid and relatively inexpensive method for a facilitated and reliable differentiation of the various nucleated cell types in urine.

Isolation and characterization of the lower portion of the thin limb of Henle in primary culture

To further characterize cells of the lower portion of the thin limb of Henle (TLH1p) under defined conditions in vitro, we developed a technique to enrich this cell population in suspension. TLH1p cells were isolated by enzymatic digestion of rat inner medulla, elimination of collecting ducts by lectin-coated beads, and differential centrifugation. Immunohistochemical staining of primary cultures of TLH1p cells with various markers revealed the preparations to be > 90% pure. The hormonal stimulation pattern of PGE2 and cAMP production by arginine vasopressin, angiotensin II, and dopamine in the isolated cells also argued against significant contamination by other cell types. Staining with an antibody against the aquaporin-1 water channel showed the distribution of cells from the ascending and descending limbs to be approximately equal in the isolated population. This technique allows the enrichment of cells from the lower portion of the thin limb of Henle in suspension to a very high degree of purity with the option to start primary cultures. Because these segments of the tubular system in particular are relatively inaccessible for microdissection, the presented method renders the possibility of addressing new questions regarding these tubular segments under defined conditions in vitro.