The profile of glycans and their recognition by endogenous receptors (lectins) are increasingly attributed to disease process. Monitoring this can provide information on the pathogenesis of Sjögren's syndrome (SS). Commonly, plant lectins are employed for phenomenological glycan mapping. To go beyond this approach restricted to binding of exogenous probes, new markers measure ligand properties of glycans to human (not plant) lectins and the presence of sugar receptors completing a protein-carbohydrate recognition system. Carrier-immobilized sugar epitopes (neoglycoproteins) and purified human lectins establish this innovative panel.
The host defence molecules mannan binding lectin, serum amyloid P component, and the macrophage migration inhibitory factor-binding sarcolectin, selected for their involvement in cell destructive mechanisms, were purified and labeled. The plant lectins SNA and MAA were employed to monitor regulation of potential ligand sites for I-type lectins and galectins. Asialofetuin was tested as a "pan-galectin selective" probe. The specific binding characteristics were determined by quantitative morphometry and statistical analysis.
Diagnostic information emerged from this analysis. The percentage of stained tissue area was significantly different between SS and control specimens after processing with GlcNAc and Man-bearing neoglycoproteins and the 2 tested serum lectins. For separation of cases of primary and secondary SS, the staining intensity with the asialoglycoprotein, sarcolectin, and the exogenous alpha2,6-sialylated glycan-binding lectin SNA was statistically significant.
Saccharide-presenting probes to measure the cellular capacity to bind glycan epitopes and human lectins as sensors for endogenous binding sites have proven to be useful as diagnostic tools. We suggest the differences we observed reflect aberrations from the normal cellular homeostasis with relevance for the pathogenesis of SS and its manifestation as a primary or secondary syndrome.