Switching on cytotoxicity by a single mutation at the heavy chain variable region of an anti-ganglioside antibody

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• 作者：Yuniel Fern&#xe1 ; ndez-Marrero^a ; Tays Hern&#xe1 ; ndez^a ; Lourdes Roque-Navarro^a ; Ariel Talavera^b ; Ernesto Moreno^b ; Tania Griñ ; &#xe1 ; n^b ; Ana Mar&#xed ; a V&#xe1 ; zquez^a ; Cristina Mateo de Acosta^a ; Rolando P&#xe9 ; rez^a ; Alejandro Ló ; pez-Requena^a ; ^{requena@cim.sld.cu}
• 关键词：Ganglioside ; GM3(Neu5Gc) ; Cytotoxic antibody
• 刊名：Molecular Immunology
• 出版年：2011
• 出版时间：April 2011
• 年：2011
• 卷：48
• 期：8
• 页码：1059-1067
• 全文大小：1227 K

文摘

Gangliosides are sialic acid-containing glycosphingolipids present in the plasma membrane of most mammalian cells. In humans, the expression of the N-glycolylated (Neu5Gc) variant of the sialic acid has been associated with malignant transformation, constituting therefore an attractive target for cancer immunotherapy. P3 monoclonal antibody (mAb) recognizes Neu5Gc-containing gangliosides, as well as sulfatides. Heavy chain CDR3 (H-CDR3) arginine residues have been shown to be crucial for ganglioside recognition, but less important for anti-idiotypic antibody binding. Here, we describe the effect on antibody reactivity of different mutations involving a single H-CDR3 acid residue. Substitution of glutamate 99 (Kabat numbering) by arginine, aspartate or serine residues resulted in no differences in anti-idiotype binding. However, the first mutation caused increased reactivity with the antigen, including a cytotoxic effect of the antibody on ganglioside-expressing cells previously unseen for the wild type antibody. Another antibody that recognizes N-glycolyl-GM3 ganglioside (GM3(Neu5Gc)), but not other glycolipids, named 14F7, exhibits also an arginine-enriched H-CDR3 and a complement-independent cell death activity. Unlike 14F7 mAb, the cytotoxicity of the P3 E₉₉ → R mutant antibody did not exclusively depend on ganglioside expression on tumor cells.