Antibody lectin sandwich assay (ALSA). (A) Graphical depiction of ALSA strategy. The hGGT1 antibodies are printed on a nitrocellulose slide and chemically derivatized to inactivate their glycans. hGGT1 is captured by the immobilized antibody and N-glycan features are probed using biotinylated lectins, which are subsequently detected using streptavidin-phycoerythrin and fluorescence scanning. (B) One printed antibody array well is shown with the magnified capture antibodies. Individual hGGT1 capture spots have been cut out to show triplicate detection of Datura stramonium lectin (DSL) among 64-fold kidney sample dilutions (equivalent to ~75 ng of total extracted kidney protein). (C) Representative results for hGGT1 capture antibody and detection reagents (indicated in the column labels).