Signaling capacity of FcgammaRII isoforms in B-CLL cells.

GAMBERALE R; FERNÁNDEZ CALLOTTI P; SANJURJO J; ARROSAGARAY G; SÁNCHEZ AVALOS JC; GEFFNER JR; GIORDANO M

LEUKEMIA RESEARCH

Año: 2005 vol. 29 p. 1277 - 1284

0145-2126

Abstract Two main isoforms of Fc receptor II (CD32) have been described in humans: activatory FcRIIA and inhibitory FcRIIB. We have previously reported that B cells from a subset of chronic lymphocytic leukemia (B-CLL) patients express not only FcRIIB, as normal B lymphocytes, but also the myeloid FcRIIA. The aim of this study was to evaluate the signaling capacity of both FcRII isoforms in B-CLL cells.We found that FcRIIA expressed by leukemic cells failed to induce Ca2+ mobilization or protein tyrosine phosphorylation, suggesting that the receptor is not functional. By contrast, FcRIIB effectively diminished BCR-triggered ERK1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo. receptor II (CD32) have been described in humans: activatory FcRIIA and inhibitory FcRIIB. We have previously reported that B cells from a subset of chronic lymphocytic leukemia (B-CLL) patients express not only FcRIIB, as normal B lymphocytes, but also the myeloid FcRIIA. The aim of this study was to evaluate the signaling capacity of both FcRII isoforms in B-CLL cells.We found that FcRIIA expressed by leukemic cells failed to induce Ca2+ mobilization or protein tyrosine phosphorylation, suggesting that the receptor is not functional. By contrast, FcRIIB effectively diminished BCR-triggered ERK1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIB, as normal B lymphocytes, but also the myeloid FcRIIA. The aim of this study was to evaluate the signaling capacity of both FcRII isoforms in B-CLL cells.We found that FcRIIA expressed by leukemic cells failed to induce Ca2+ mobilization or protein tyrosine phosphorylation, suggesting that the receptor is not functional. By contrast, FcRIIB effectively diminished BCR-triggered ERK1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIA. The aim of this study was to evaluate the signaling capacity of both FcRII isoforms in B-CLL cells.We found that FcRIIA expressed by leukemic cells failed to induce Ca2+ mobilization or protein tyrosine phosphorylation, suggesting that the receptor is not functional. By contrast, FcRIIB effectively diminished BCR-triggered ERK1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIA expressed by leukemic cells failed to induce Ca2+ mobilization or protein tyrosine phosphorylation, suggesting that the receptor is not functional. By contrast, FcRIIB effectively diminished BCR-triggered ERK1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIB effectively diminished BCR-triggered ERK1 phosphorylation, which indicates that it is able to transduce inhibitory signals in B-CLL cells. Moreover, we found that FcRIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIB homoaggregation in either B-CLL or non-malignant tonsillar B cells did not result in apoptosis as was reported for murine B splenocytes. Together, these results show that FcRIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIB, but not FcRIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.RIIA is biologically active in B-CLL cells and might influence leukemic cell physiology in vivo.