Activation of human monocyte/macrophage cytotoxicity by IL-2/IFNgamma is linked to increased expression of an antitumor receptor with specificity for acetylated mannose

Journal/Book: Immunol-Let 38 (2), 111-119. 1993;

Abstract: Spontaneous cytotoxicity of human monocytes (purity: 92-95%) againstK562 tumor cells was only observed in 31% healthy donors but, in thepresence of rhamnogalacturonan (500 ng/ml), enhanced cytotoxicity wasrecorded for 79% (n = 14) of the donors. Monocytes activated byculturing with interleukin-2 and/or IFN(gamma) showed increasedantitumor cytotoxicity against K562 tumor cells in 86% (n = 21) of thedonors exhibiting additional increases in specific cytotoxicity when thecytotoxicity assays were carried out in the presence ofrhamnogalacturonan. Increases of monocyte cytotoxicity achieved byactivation with cytokines coincided with increased formation ofmonocyte/tumor cell conjugates. Similarly, increased monocytecytotoxicity mediated by rhamnogalacturonan also correlated withincreased monmocyte/tumor cell conjugate formation most likely due toeffector cell/target cell bridging as was originally described forrhamnogalacturonan interacting with CD56+ natural killer orlymphokine-activated killer cells and tumor cells. The chemospecificityof the monocyte-based receptors responsible for cytotoxicity and formonocyte/tumor cell conjugate formation, as well as for theirrhamnogalacturonan-mediated enhancements, appears to be identical sinceall these effects could be inhibited in a dose-dependent manner bypartially deacetylated (60%) mannose pentaacetate.

Keyword(s): Medical:monocyte

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