This alone shows that it is organized in a way different from the plasma membrane. WGA is an indicator for fungi mycelin in infected plant tissue. For electron microscopic studies have the lectins to be tagged with electron-dense markers like ferritin or colloidal gold. These complexes enable the detection of different distribution at the membrane's inner and outer surface. It can therefor not be said without further analysis whether the receptor is an oligo- or a polysaccharide, a glycoprotein or a glycolipid.
Lectins detect only a rather small range of sugars.
There exist no lectins that detect, for example, arabinose or xylose residues. Antibodies are a rather homogeneous group of proteins that occur in the serum of vertebrates protecting the animal from foreign influences like infections with bacteria or viruses or from tumour cells. Plants have no antibodies. Such a signal has to be of a macromolecular nature. It may be part of a cell surface.