Enhancement of MHC-unrestricted cytotoxic activity of human CD56+CD3-natural killer (NK) cells and CD3+T cells by rhamnogalacturonan: target cell specificity and activity against NK-insensitive targets

Journal/Book: J. Cancer Res. Clin. Oncol. 120, 383-388. 1994;

Abstract: Rhamnogalacturonan-mediated enhancement of MHC-unrestricted cytotoxicitywas studied with freshly isolated CD56+CD3- natural killer (NK) cells,interleukin-2 (IL-2)-activated CD56+ lymphokine-activated killer (LAK)cells und IL-2/anti-CD3-activated T cells as effector cells usingNK-sensitive and NK-insensitive tumor cells as targets. Therhamnogalacturonan fractions IM, IP, and IQ were prepared fromcommercially available extracts of Viscum album. The dose/responserelation of IM, IP, and IQ demonstrated the presence of variousconcentrations of cytotoxicity-enhancing compounds in all threefractions that were identified as rhamnogalacturonans by degradationstudies with poly-alpha-D-galacturonidase (EC 3.2.1.15) andalpha-1,6-rhamnosidase (EC 3.2.1.40). Specific cytotoxicity of all threeeffector cell populations as well as the respectiverhamnoagalacturonan-mediated cytotoxicity enhancement was readilyinhibited in a dose-dependent manner by 60%-deacetylated mannosepentaacetate. Rhamnogalacturonan-mediated enhancement of cytotoxicity offresh CD56+ NK cells was also observed with four of five NK-insensitivetumor cells as targets, indicating that the effector-cell/tumor-cellbridging activity of rhamnogalacturonans renders NK-insensitive targetssusceptible to NK-mediated lysis. Moreover, therhamnogalacturonan-mediated cytotoxicity enhancement became even moreprominent when lymphokine-activated CD56+ LAK and CD3+ T cells wereassayed with the NK-insensitive tumor cell targets. Author.

Keyword(s): ANTIGENS-CD

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