Establishment of a Human Monoclonal Antibody to Hanganutziu‐Deicher Antigen as a Tumor‐associated Carbohydrate Antigen

We have established a human‐human hybridoma producing a monoclonal antibody against a tumor‐associated carbohydrate‐specific antigen, Hanganutziu‐Deicher (HD) antigen. Human spleen lymphocytes from a patient with esophageal varices complicated with liver cirrhosis were cultured in serum‐free medium and co‐stimulated with both anti‐human μ‐chain antibodies and supernatants of concanavalin A‐stimulated human spleen cell culture (ConA sup). The activated lymphocytes were subsequently primed in vitro with particulate HD3 antigen and fused with a parent hybrid myeloma cell line, KR‐12. A hybridoma, 1F43E31G7 produced anti‐HD human monoclonal antibody (IgM λ). This monoclonal antibody reacted strongly with N‐glycolyl‐neuraminyl α2‐3 lactosylceramide (HD3) and slightly with N‐glycolylneuraminyl α2‐3 lactoneotetraosylceramide (HD3), but did not react with N‐glycolylneuraminyl α2‐3 lactoneohexaosylceramide (HD7), N‐acetylneuraminyl α2‐3 lactosylceramide (GM3) and other derivatives of HD3 prepared by chemical modification of the sialic acid residue of HD3, which indicates that the monoclonal antibody is directed precisely toward the terminal sialic acid and whole structure of HD3.