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Differentially regulated expression and function of CD22 in activated B-1 and B-2 lymphocytes

Nitschke, Lars
Martinez-Soria, Eduardo
Parkhouse, R. Michael
Published in Journal of Immunology. 2002, vol. 168, no. 12, p. 6078-6083
Abstract CD22 is a B cell-restricted transmembrane protein that apparently controls signal transduction thresholds initiated through the B cell Ag receptor (BCR) in response to Ag. However, it is still poorly understood how the expression of CD22 is regulated in B cells after their activation. Here we show that the expression levels of CD22 in conventional B-2 cells are markedly down-regulated after cross-linking of BCR with anti-IgM mAb but are up-regulated after stimulation with LPS, anti-CD40 mAb, or IL-4. In contrast, treatment with anti-IgM mAb barely modulated the expression levels of CD22 in CD5(+) B-1 cells, consistent with a weak Ca(2+) response in anti-IgM-treated CD5(+) B-1 cells. Moreover, in CD22-deficient mice, anti-IgM treatment did not trigger enhanced Ca(2+) influx in CD5(+) B-1 cells, unlike CD22-deficient splenic B-2 cells, suggesting a relatively limited role of CD22 in BCR signaling in B-1 cells. In contrast, CD22 levels were markedly down-regulated on wild-type B-1 cells in response to LPS or unmethylated CpG-containing oligodeoxynucleotides. These data indicate that the expression and function of CD22 are differentially regulated in B-1 and conventional B-2 cells, which are apparently implicated in innate and adaptive immunity, respectively.
Keywords Adjuvants, Immunologic/pharmacologyAnimalsAntibodies, Anti-Idiotypic/pharmacologyAntibodies, Monoclonal/pharmacologyAntigens, CD/ biosynthesis/metabolism/physiologyAntigens, CD22Antigens, CD40/immunologyAntigens, Differentiation, B-Lymphocyte/ biosynthesis/metabolism/physiologyB-Lymphocyte Subsets/ immunology/ metabolismCalcium/metabolismCalcium Signaling/immunologyCell Adhesion MoleculesCells, CulturedCpG Islands/immunologyDown-Regulation/immunologyImmunoglobulin M/immunologyInterleukin-4/pharmacologyLectinsLipopolysaccharides/pharmacologyLymphocyte Activation/ immunologyMiceMice, Inbred C57BLMice, KnockoutMice, Mutant StrainsOligodeoxyribonucleotides/pharmacologyPeritoneum/cytology/immunology/metabolismSpleen/cytology/immunologyUp-Regulation/immunology
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PMID: 12055217
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