Susceptibility of rat colon carcinoma cells to lymphokine activated killer-mediated cytotoxicity is decreased by alpha1,2-fucosylation

The presence of alpha1,2-fucosylated glycans at the surface of rat colon carcinoma cells has been associated with an increased tumorigenicity and resistance to natural killer/lymphokine activated killer (NK/LAK) cytotoxicity. We now report that transfection of rat alpha1,2-fucosyltransferases cDNA (FTA and FTB) into REG cells, which are spontaneously devoid of this enzymatic activity, allows expression of histo-blood group H antigen and increases their resistance to LAK, but not NK cell lysis. Conversely, transfection of PRO cells, which spontaneously express alpha1, 2-fucosyltransferase activity, with the FTA cDNA in the antisense orientation decreases expression of the H antigen together with their resistance to LAK cell lysis, but again, not to NK cell lysis. Furthermore, REG cells that are rejected by immunocompetent syngeneic rats are similarly rejected by rats depleted of NK cells by antibody 3.2.3, directed against the NKR-P1 molecule. Thus, the rejection of REG cells by immunocompetent rats and their earlier reported increased tumorigenicity after transfection with an alpha1, 2-fucosyltransferase cDNA cannot be ascribed to NK cell sensitivity or resistance, respectively. The increased resistance to LAK cell lysis, however, may be relevant to tumor progression.