Pancreatic islet cell surface glycoproteins containing Gal beta 1-4GlcNAc-R identified by a cytotoxic monoclonal autoantibody.

Lactose inhibited the binding of the epitope-specific mAb E5C2 to rat insulinoma cells R1Nm5F or neuraminidase-treated primary rat pancreatic islet cells by indirect immunofluorescence. Lactose also inhibited the binding of the mAb E5C2 to glycolipids from human HL-60 cells. Lactose inhibited binding 20-30 times less effectively than the epitope N-acetyllactosamine. Lactose inhibited binding by mAb E5C2 to 60,000 and 68,000 MW proteins from R1Nm5F cell extracts on neuraminidase-treated Western blots.