IMMUNOLOGICAL CROSS-REACTIVITIES BETWEEN PROTEINS SECRETED BY THE SUBCOMMISSURAL ORGAN, AND PLANT-LECTINS

The glial subcommissural organ (SCO) discharges a glycoprotein-rich se cretory product into the third ventricle to form Reissner's fibre (RF) . The SCO proteins bear N-linked oligosaccharides, such as mediate man y cell-cell and cell-matrix interactions. In such interactions the cor responding partner molecule recognising the sugar chain is often a sug ar-specific protein (lectin). We present here evidence that the consti tuents of the SCO secretory product include proteins immunologically c ross-reactive with certain plant lectins. Polyclonal antisera directed against Phaseolus vulgaris agglutinin-L (PHA-L) labelled the apically released RF-material of the rat SCO. Indirect ELISA studies shows in addition that anti-RF antisera bound to certain plant lectins (PHA-L, Con A). Dot spot assays demonstrated binding of anti-PHA-L to RF prote ins. In Western blots of RF proteins anti-PHA-L, anti-RCA and anti-Con A bound to distinctive subsets of the RF protein fractions.