Sertoli cell expression of galectin-1 and-3 and accessible binding sites in normal human testis and Sertoli cell only-syndrome

Galectins are vertebrate lectins interacting with beta-galactosides and der ivates thereof such as blood group A, B and H determinants. The expression of galectin-1 and -3 and galectin-specific binding sites by human Sertoli c ells was analyzed in normal human testis and Sertoli cell only-syndrome (SC OS). Staining intensity was scored semiquantitatively on a 4-grade scale. S ertoli cells in normal testes displayed a moderate cytoplasmic and weak nuc lear staining for galectin-1-specific binding sites. Galectin-3-specific bi nding sites were expressed in Sertoli cells less intensely than accessible ligands for galectin-1 (mean score 2.25 for galectin-1 and 1.50 for galecti n-3). Germ cells were only weakly reactive. Tubular walls were negative for both classes of galectin-specific binding sites. In SCOS, galectin-1 bindi ng was moderate to strong and more pronounced than galectin-3 binding by Se rtoli cells (mean scores 4.00 and 2.25). Tubular walls were negative for ga lectin-staining. The ratio for galectin-1-/galectin-3-specific binding (sta ining score ratio) was 1.50 form normal testis and 1.78 for SCOS disclosing a relative increase of galectin-3 binding sites in the latter. Staining wi th galectin-1- and -3-specific antisera showed a strong cytoplasmic galecti n-1 immunoreactivity in Sertoli cells of normal and SCOS testis (score 4.00 for both). Anti-galectin-3 did not stain Sertoli cells or germ cells in no rmal testis. Only Leydig cells were labeled (score 3.00). In SCOS a weak to moderate nuclear staining of Sertoli cells was noted (score 2.00). Galectin-3 expression and galectin-1-specific binding sites were found to b e increased in Sertoli cells of SCOS. This modulation of reactivity can hav e implications for Sertoli cell interactions with galectin-reactive extrace llular matrix components like laminin and for anti-apoptotic effects.