E2A、EBF和PAX5在早期B细胞分化发育中的作用

早期B细胞分化发育受到各种转录因子调控,特别是转录因子E2A、早期B细胞因子(EBF)及PAX5的调控尤为重要。本文以E2A、EBF与PAX5三个转录因子为综述对象,逐一阐述其在早期B细胞分化发育中的作用,并对3个转录因子在早期B细胞分化发育中的协同作用进行了综述。本文将为"B淋巴细胞分化发育调控机理研究"提供参考。     

B cell growth and differentiation factors interact with receptors distinct from the interleukin 2 receptor

Human B lymphocytes preactivated with Staphylococcus aureus Cowan strain I can proliferate and differentiate to Ig-secreting cells when cultured in the presence of recombinant interleukin 2 (IL2). We have compared 2 different B cell growth factors (BCGF) and a B cell differentiation factor (BCDF) to IL2 in the regulation of human B lymphocyte growth and differentiation. Utilizing a competitive binding assay, neither a high molecular weight BCGF (HMW-BCGF) nor a low molecular weight BCGF (LMW-BCGF) competitively inhibited the binding of radiolabeled IL2. Blocking studies with the anti-Tac monoclonal antibody demonstrated that B cell proliferation to IL2 was inhibited while a crude supernatant containing BCGF and IL2 was only partially inhibited. B cell Ig secretion induced by IL2 was also inhibited by anti-Tac while a crude supernatant and partially purified BCDF were not. Furthermore, IL2 plus BCGF was shown to enhance B cell proliferation better than either factor alone and IL2 plus a BCDF enhanced B cell Ig secretion better than either factor alone. By separating activated B cells into Tac-positive and Tac-negative fractions, much of the previously noted enhancement with the 2 factors was found to be secondary to the differential sensitivity of the 2 populations to BCGF and IL2 or BCDF and IL2. Thus, LMW-BCGF, HMW-BCGF and a partially purified BCDF appear to interact with receptors distinct from the IL2 receptor in mediating their effects on B cell growth and differentiation.     

转录因子的氧化还原调节

细胞内氧化和抗氧化物质的平衡影响着细胞的生长、分化、凋亡和坏死等。活性氧(reactive oxygenspecies ROS)是一类性质十分活泼的化学基团,它主要包括超氧自由基、羟自由基、氢过氧化物自由基、过氧化氢和单线态氧。以往人们对ROS的研究主要集中在它的病理作用上。近年来,随着分子生物学技术的发展和应用,ROS的生理作用越来越引起人们的关注。目前,细胞内氧化物、抗氧化物以及氧化还原态的其它决定因素对细胞内转录因子活化和继之发生的基因表达的调节已成为研究的热点。大量转录因子的活性及其与DNA的结合活性,是受细胞内的氧化还原…     

The response of selected human B cell lines to B cell growth and differentiation factors

Fifteen human B cell lines were tested for their ability to respond to B cell growth and differentiation factors present in phytohemagglutinin-conditioned medium. Five lines responded significantly: CESS showed an increase in IgG production only, HFB1 and BALM1 showed an increase in proliferation only and L4 and BALM4 showed an increase in both IgG production and proliferation. When four of the responding lines (CESS, HFB1, L4 and BALM4) were cultured with human recombinant-derived interleukin 1, interleukin 2, interleukin 4 or interferon-gamma no significant response was seen. CESS, L4 and BALM4 all increased IgG production in response to partially purified B cell growth factor (Cellular Products, Inc., Sera-Lab., Crawley Down, GB) and B cell differentiation factor-containing supernatant from the T24 bladder carcinoma cell line. HFB1, L4 and BALM4 all showed increased tritiated thymidine incorporation in response to purified B cell growth factor but not in response to B cell differentiation factor-containing supernatant. These lines may prove useful in the study of B cell growth and differentiation factors and their receptors.     

IgE-binding factors. Selective regulation of the IgE response by T cell factors

Gene cloning of rodent IgE-binding factors was accomplished, using messenger RNA of a rat T cell hybridoma, 23B6, which produce IgE-suppressive factor. Transfection of cos 7 monkey kidney cells with a cDNA clone resulted in the formation of rodent IgE-potentiating factors. The results provided a definitive evidence that IgE-binding factors represent a single peptide chain, and that the IgE-potentiating factor and IgE-suppressive factor share a common structural gene. Nucleotide sequence of a cDNA provided predicted amino acid sequence of the 60K precursor molecules of IgE-potentiating factor. Human IgE-potentiating factors were obtained from a human T-T hybridoma. The factors have affinity not only for human IgE but also for rat IgE and selectively enhanced antigen-induced IgE response of rat lymphocytes. The same hybridoma could be switched to form IgE-suppressive factor by the addition of glycosylation-inhibiting factor (GIF) during its biosynthesis. Purified GIF has immunosuppressive activity in the mouse. This factor suppressed the primary IgE and IgG antibody responses in the mouse, and markedly suppressed ongoing IgE antibody formation.