A hybridoma producing
monoclonal antibody (H11) directed to
lactoneotetraosylceramide (
paragloboside) has been established from spleen cells of a mouse immunized with
paragloboside. The
monoclonal antibody H11 (
immunoglobulin M type) was selected from five clones showing different reactivities with
paragloboside. The
monoclonal antibody was highly specific to
paragloboside and lacked reactivity with other
glycolipids including
glucosylceramide,
lactosylceramide,
globotriaosylceramide,
globotetraosylceramide, gangliotriaosylceramide,
gangliotetraosylceramide, and GalNAc beta 1-4[NeuAc alpha 2-3]Gal beta 1-4Glc beta 1-1Cer. However, the
monoclonal antibody (H11) was found to bind to
lactosamine-containing
glycolipids at their terminals, such as i- and I-type
glycolipids as well as
paragloboside. A two-step sandwich radioimmunoassay method for
paragloboside antigen in serum was established by using the
monoclonal antibody. The mean
paragloboside antigen concentration in the sera from 20 normal individuals was 25.3 ng/ml. If the cutoff value was set at 80.9 ng/ml [25.3 + 2 x 27.8 (SD)], only 1 of 20 healthy controls had an elevated
paragloboside value in the serum, whereas sera from 9 of 12 (75.0%)
hepatoma, 4 of 10 (40%)
pancreatic cancer, 16 of 40 (40.0%)
stomach cancer, and 6 of 10 (60%)
lung cancer patients had elevated
paragloboside values. Sera from 3 of 8
hepatitis patients and 7 of 10
liver cirrhosis patients were estimated to be positive but sera from 16 patients with benign disease had
paragloboside levels lower than the cutoff value. A larger amount of the
antigen was found in liver
metastases from
colorectal carcinoma compared to the normal counterpart. The
antigen was also detected in the medium of various human
cancer cells and meconium. However, the
antigen in the sera, medium, meconium, and
cancer tissue seemed to be associated with
glycoprotein or
lipoprotein, because most of the
antigen activity was eluted in the void volume fraction on high-performance liquid chromatography with a gel filtration column.