Ganglioside GM2 as a human tumor antigen (OFA-I-1).

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Abstract
A monospecific antibody produced in vitro by a [human] .beta. lymphoblastoid cell line transformed with Epstein-Barr virus recognizes a membrane antigen (OFA-I-1) on human tumors and fetal brain. The chemical nature of OFA-I-1 is identified. The glycolipid fraction of antigen-rich spent medium of an OFA-I-1-positive melanoma cell line, M14, was extracted by chloroform/methanol/water, 4:8:3 (vol/vol), and was separated into fractions of neutral glycolipids and gangliosides by DEAE-Sephadex followed by base treatment and Bio-sil A column elution. OFA-I-1 antigens were found exclusively in the ganglioside fraction when assayed with monospecific anti-OFA-I-1 by an immune adherence inhibition test. The results obtained from TLC of the antigenic M14 ganglioside and sequential glycosidase digestion suggested that the antigen was a ganglioside GM2, GalNAc.beta.1 .fwdarw. 4 (NeuAc.alpha.2 .fwdarw. 3)Gal.beta.1 .fwdarw. 4Glc .fwdarw. Cer. The results were further supported by testing various authentic gangliosides and neutral glycolipids for OFA-I-1 antigenicity. Only GM2 showed positive reactivity.