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* Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
Department of Microbiology and Immunology and
Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
The transcription factor Bright up-regulates Ig H chain production from select V region promoters and requires Bright dimerization, Brutons tyrosine kinase (Btk), and the Btk substrate, TFII-I, for this activity. Defects in Btk cause X-linked immunodeficiency disease in mice and humans. Btk-deficient mice exhibit decreased serum IgM production, B cell developmental blocks, absence of peritoneal B1 cells, and subnormal immune responses against Ags, including phosphorylcholine, which confer protection against Streptococcus pneumoniae. Transgenic mice expressing dominant-negative Bright share similarities with Btk-deficient mice, including decreased serum IgM, poor anti-phosphorylcholine responses, and slightly reduced numbers of mature B cells. Although dominant-negative Bright mice developed B1 B cells, these were functionally deficient in Ig secretion. These data suggest a mechanistic explanation for the abnormal responses to phosphorylcholine observed in Btk-deficient mice, and indicate that Bright functions in a subset of Btk-dependent pathways in vivo, particularly those responses dominated by B1 B cells.
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1 This work was supported by National Institutes of Health Grant AI44215.
2 Address correspondence and reprint requests to Dr. Carol F. Webb, 825 N. E. 13th St., Oklahoma City, OK 73104. E-mail address: webbc{at}omrf.org
3 Abbreviations used in this paper: ARID, A + T-rich interacting domain; Btk, Brutons tyrosine kinase; DN, dominant negative; FOL, follicular mature; KLH, keyhole limpet hemocyanin; MZ, marginal zone; NP, nitrophenyl; PC, phosphorylcholine; TG, transgenic; WT, wild type.
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