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1: J Immunol 2002 Jan 15;168(2):629-34

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The pre-B cell receptor signaling for apoptosis is negatively regulated by Fc gamma RIIB.

Kato I, Takai T, Kudo A.

Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.

Many studies have shown that FcgammaRIIB is a negative regulator of B cell receptor signaling, and even though FcgammaRIIB is expressed through all developmental stages of the B cell lineage, its involvement in pre-B cell receptor (pre-BCR) signaling has not been examined. To investigate FcgammaRIIB function at the pre-B cell stage, we have established pre-BCR positive pre-B cell lines from normal mice and FcgammaRIIB-deficient mice, named PreBR and Fcgamma(-/-)PreBR, respectively. These cell lines are able to differentiate into immature B cells in vitro by removal of IL-7. In PreBR, apoptosis was moderately induced by F(ab')(2) anti-mu Ab, but not by intact anti-mu Ab. Phosphorylation of SH2-containing inositol 5-phosphatase (SHIP) and Dok, which are involved in FcgammaRIIB signaling, was induced by anti-mu cross-linking in PreBR. In contrast, apoptosis was strongly induced by both the F(ab')(2) and intact anti-mu Abs in Fcgamma(-/-)PreBR, and the level of phosphorylation of SHIP or Dok was much lower in Fcgamma(-/-)PreBR than those observed in PreBR. Restoration of FcgammaRIIB to Fcgamma(-/-)PreBR followed by anti-mu cross-linking blocked severe apoptosis, and up-regulated SHIP and Dok phosphorylation. The results demonstrate that FcgammaRIIB negatively regulates pre-BCR-mediated signaling for apoptosis.

PMID: 11777955 [PubMed - indexed for MEDLINE]

i686-pc-linux-gnu Jul 16 2002 16:34:53