Glucocorticoid-induced TNF receptor-triggered T cells are key modulators for survival/death of neural stem/progenitor cells induced by ischemic stroke

Increasing evidences show that immune response affects the reparative mechanisms in injured brain. Recently, we have demonstrated that CD4(+)T cells serve as negative modulators in neurogenesis after stroke, but the mechanistic detail remains unclear. Glucocorticoid-induced tumor necrosis factor (TNF) receptor (GITR), a multifaceted regulator of immunity belonging to the TNF receptor superfamily, is expressed on activated CD4(+)T cells. Herein, we show, by using a murine model of cortical infarction, that GITR triggering on CD4(+)T cells increases poststroke inflammation and decreases the number of neural stem/progenitor cells induced by ischemia (iNSPCs). CD4(+)GITR(+)T cells were preferentially accumulated at the postischemic cortex, and mice treated with GITR-stimulating antibody augmented poststroke inflammatory responses with enhanced apoptosis of iNSPCs. In contrast, blocking the GITR-GITR ligand (GITRL) interaction by GITR-Fc fusion protein abrogated inflammation and suppressed apoptosis of iNSPCs. Moreover, GITR-stimulated T cells caused apoptosis of the iNSPCs, and administration of GITR-stimulated T cells to poststroke severe combined immunodeficient mice significantly reduced iNSPC number compared with that of non-stimulated T cells. These observations indicate that among the CD4(+)T cells, GITR(+)CD4(+)T cells are major deteriorating modulators of poststroke neurogenesis. This suggests that blockade of the GITR-GITRL interaction may be a novel immune-based therapy in stroke.

Selective granulocyte and monocyte apheresis as a new adjunct to enhance the efficacy of interferon-alpha + ribavirin in patients with high plasma hepatitis C virus

BACKGROUND AND AIM

Selective granulocyte and monocyte/macrophage adsorptive apheresis is to increase the turnover of infected leucocytes and has increased CD4+ T cells, which are necessary for actions of interferon-alpha on hepatitis C virus. Therefore, granulocyte and monocyte apheresis was to enhance the efficacy of interferon + ribavirin.

METHODS

Fifteen patients, 12 had interferon resistant hepatitis C virus and 3 were interferon naive. Hepatitis C virus genotype was 1b in 11 and 2a in 4. The mean plasma HCV-RNA was 728.3 kU/mL and alanine aminotransferase was 107.5 U/L. Granulocyte and monocyte apheresis was with the Adacolumn, which contains carriers that adsorb granulocytes and monocytes/macrophages. After five consecutive granulocyte and monocyte apheresis sessions over 5 days, interferon daily 6 million units for 4 weeks, then three times/week for 20 weeks+ribavirin (600-800 mg per patient per day) were given and followed for another 24 weeks.

RESULTS

During granulocyte and monocyte apheresis, plasma HCV-RNA transiently fell by up to 55%. Similarly, incubation of blood with the Adacolumn carriers caused a significant fall in HCV-RNA. Four patients were unavailable for efficacy evaluation. In the other 11, alanine aminotransferase normalised and at 11 weeks, plasma HCV-RNA was negative; six of these (55%) maintained their remission during the follow up.

CONCLUSION

Granulocyte and monocyte apheresis appears to deplete extra-hepatic hepatitis C virus reservoirs and generate active complement opsonins, which contribute to hepatitis C virus killing. Additional mechanism(s) are also likely and need to be elucidated in future studies with larger cohort of patients.

Plasmodium berghei infection in mice induces liver injury by an IL-12- and toll-like receptor/myeloid differentiation factor 88-dependent mechanism

Malaria, caused by infection with Plasmodium spp., is a life cycle-specific disease that includes liver injury at the erythrocyte stage of the parasite. In this study, we have investigated the mechanisms underlying Plasmodium berghei-induced liver injury, which is characterized by the presence of apoptotic and necrotic hepatocytes and dense infiltration of lymphocytes. Although both IL-12 and IL-18 serum levels were elevated after infection, IL-12-deficient, but not IL-18-deficient, mice were resistant to liver injury induced by P. berghei. Neither elevation of serum IL-12 levels nor liver injury was observed in mice deficient in myeloid differentiation factor 88 (MyD88), an adaptor molecule shared by Toll-like receptors (TLRs). These results demonstrated a requirement of the TLR-MyD88 pathway for induction of IL-12 production during P. berghei infection. Hepatic lymphocytes from P. berghei-infected wild-type mice lysed hepatocytes from both uninfected and infected mice. The hepatocytotoxic action of these cells was blocked by a perforin inhibitor but not by a neutralizing anti-Fas ligand Ab and was up-regulated by IL-12. Surprisingly, these cells killed hepatocytes in an MHC-unrestricted manner. However, CD1d-deficient mice that lack CD1d-restricted NK T cells, were susceptible to liver injury induced by P. berghei. Collectively, our results indicate that the liver injury induced by P. berghei infection of mice induces activation of the TLR-MyD88 signaling pathway which results in IL-12 production and activation of the perforin-dependent cytotoxic activities of MHC-unrestricted hepatic lymphocytes.

Expression of interleukin-18 and its receptor in mouse ovary

PROBLEM

Interleukin-18 (IL-18) strongly induces interferon-gamma production and is produced not only by types of immune cells but also by types of non-immune cells. Ovulation is thought to be an inflammation-like reaction in which many pro-inflammatory cytokines are involved. We investigated whether IL-18 is involved in the functions of ovary.

METHOD OF STUDY

The 4-week-old immature female mice were examined for IL-18 and IL-18 receptor (IL-18R) expression on their ovaries under stimulation with pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) by immunohistochemical staining, Western blotting and reverse transcript-polymerase chain reaction. The IL-18R was blocked by the injection of anti-IL-18R monoclonal antibody to immature mice during PMSG-hCG stimulation, and the number of ovulated ova was counted.

RESULTS

The expression of both proteins and mRNA of IL-18 and IL-18R were very low in immature ovaries before stimulation, but after PMSG injection both IL-18 and IL-18R increased dramatically in theca cells and reached a maximum level at the peri-ovulatory phase then slightly lowered, but still kept a high level during the luteal phase in the corpus luteum. The treatment of IL-18R monoclonal antibody to the mice during ovarian stimulation reduced the number of ovulated ova and inhibited the expansion of cumulus cells surrounding the ovum.

CONCLUSION

IL-18 and IL-18R play roles in various kinds of function of ovary.

Interleukin-18 stimulates hematopoietic cytokine and growth factor formation and augments circulating granulocytes in mice

Because interleukin-18 (IL-18) is similar to IL-1 and is known to be involved in the hematopoietic progenitor cell growth, the effect of IL-18 on circulating cell populations was examined. Repeated administration of IL-18 induced significant amounts of neutrophilia in mice. In parallel, high levels of interferon-gamma (IFN-gamma), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were detected in the serum of these mice. Interestingly, the cytokine profiles as well as the cell populations in circulation altered around 2 weeks after the beginning of IL-18 administration. A weak but definite eosinophilia was observed concurrently with the appearance of serum IL-5. Consistent with these observations, IL-18 induced secretion of IFN-gamma, GM-CSF, and IL-6 from splenocytes in culture. IL-18 also induced low levels of IL-5 in the splenocyte culture, which was inhibited by IL-12. However, markedly high levels of IL-5 were secreted into the culture medium when splenocytes from IFN-gamma-deficient mice were stimulated by IL-18. CD4(+) T cells strongly responded to IL-18 to secrete IL-5 and GM-CSF. IL-18 stimulated secretion of IL-6 and expression of G-CSF mRNA in splenic adherent cells. Expression of IL-18 receptors was detected in CD4(+) T cells and splenic adherent cells (macrophages). These results show that IL-18 stimulates CD4(+) T cells and macrophages to secrete IL-5, GM-CSF, IL-6, and granulocyte-colony stimulating factor in the absence of IL-12, which in turn induces hematopoietic cell proliferation causing neutrophilia and eosinophilia in mice.

Potentiality of interleukin-18 as a useful reagent for treatment and prevention of Leishmania major infection

Interleukin-18 (IL-18) is a proinflammatory cytokine that plays an important role in natural killer cell activation and the T helper 1 (Th1) cell response, particularly in collaboration with IL-12. Since Th1 cells play a pivotal role in the host defense against infection with intracellular microbes, such as Leishmania major, we investigated whether IL-18 is critically involved in protection against L. major infection by activation of Th1 cells. We administered IL-12 and/or IL-18 daily to L. major-susceptible BALB/c mice. Neither IL-12 (10 ng/mouse) nor IL-18 (1,000 ng/mouse) induced wound healing, while daily injection of IL-12 and IL-18 during the first week after infection strongly protected the mice from footpad swelling by induction and activation of Th1 cells. Furthermore, these mice acquired protective immunity. We also investigated a protective role of endogenous IL-18 by using anti-IL-18 antibody-treated C3H/HeN mice (an L. major-resistant strain) or IL-18 deficient (IL-18(-/-)) mice with a resistant background (C57BL/6). We found that in the absence of endogenous IL-18, these mice showed prolonged footpad swelling as well as diminished nitric oxide production. However, daily injection of IL-18 into IL-18(-/-) mice corrected their deficiencies, suggesting that these mice have Th1 cells that produce gamma interferon (IFN-gamma) in response to IL-18. Indeed, these mice had normal levels of Th1 cells. Thus, IL-18 is not responsible for inducing Th1 cells but participates in host resistance by its action in stimulating Th1 cells to produce IFN-gamma. Our results also indicate the high potentiality of IL-18 as a useful reagent for treatment as well as prevention against reinfection.

Kupffer cells from Schistosoma mansoni-infected mice participate in the prompt type 2 differentiation of hepatic T cells in response to worm antigens

Infection with Schistosoma mansoni, a portal vein-residing helminth, is well known to generate life cycle-dependent, systemic immune responses in the host, type 1 deviation during the prepatent period, and type 2 polarization after oviposition. Here we investigated local immunological changes in the liver after infection. Unlike splenocytes, hepatic lymphocytes from infected mice during the prepatent period already produced a higher amount of IL-4 and a lesser amount of IFN-gamma than those from uninfected mice. Hepatic lymphocytes, particularly conventional T cells, but not NK1.1+ T cells, promptly produced IL-4 in response to worm products, soluble worm Ag preparation (SWAP), whenever presented by Kupffer cells from infected mice. The hepatic lymphocytes that had been stimulated with SWAP presented by infected mice-derived Kupffer cells produced a huge amount of IL-4, IL-13, and IL-5 as well as little IFN-gamma in response to immobilized anti-CD3 mAb. Kupffer cells from uninfected mice produced IL-6 and IL-10, but not IL-12 or IL-18, in response to SWAP stimulation and gained the potential to additionally produce IL-4 and IL-13 after the infection. These results suggested that prompt type 2 deviation in the liver after the infection might be due to the alteration of Kupffer cells that induces SWAP-mediated type 2-development of hepatic T cells.

Caspase-1-independent, Fas/Fas ligand-mediated IL-18 secretion from macrophages causes acute liver injury in mice

IL-18, produced as a biologically inactive precursor, is processed by caspase-1 in LPS-activated macrophages. Here, we investigated caspase-1-independent processing of IL-18 in Fas ligand (FasL)-stimulated macrophages and its involvement in liver injury. Administration of Propionibacterium acnes (P. acnes) upregulated functional Fas expression on macrophages in an IFNgamma-dependent manner, and these macrophages became competent to secrete mature IL-18 upon stimulation with FasL. This was also the case for caspase-1-deficient mice. Administration of recombinant soluble FasL (rFasL) after P. acnes priming induced comparable elevation of serum IL-18 in parallel with elevated serum liver enzyme levels. However, liver injury was not induced in IL-18-deficient mice after rFasL administration. These results indicate a caspase-1-independent pathway of IL-18 secretion from FasL-stimulated macrophages and its critical involvement in FasL-induced liver injury.

IL-18 up-regulates perforin-mediated NK activity without increasing perforin messenger RNA expression by binding to constitutively expressed IL-18 receptor

IL-18 is a powerful inducer of IFN-gamma production, particularly in collaboration with IL-12. IL-18, like IL-12, also augments NK activity. Here we investigated the molecular mechanism underlying the up-regulation of killing activity of NK cells by IL-18. IL-18, like IL-12, dose dependently enhanced NK activity of splenocytes. This action was further enhanced by costimulation with IL-12. Treatment with anti-IL-2R Ab did not affect IL-18- and/or IL-12-augmented NK activity, and splenocytes from IFN-gamma-deficient mice showed enhanced NK activity following stimulation with IL-12 and/or IL-18. Splenocytes from the mice deficient in both IL-12 and IL-18 normally responded to IL-18 and/or IL-12 with facilitated NK activity, suggesting that functional NK cells develop in the absence of IL-12 and IL-18. IL-18R, as well as IL-12R mRNA, was constitutively expressed in splenocytes from SCID mice, which lack T cells and B cells but have intact NK cells, and in those from IL-12 and IL-18 double knockout mice. NK cells isolated from SCID splenocytes expressed IL-18R on their surface. IL-18, in contrast to IL-12, did not enhance mRNA expression of perforin, a key molecule for exocytosis-mediated cytotoxicity. However, pretreatment with concanamycin A completely inhibited this IL-18- and/or IL-12-augmented NK activity. Furthermore, IL-18, like IL-12, failed to enhance NK activity of splenocytes from perforin-deficient mice. These data suggested that NK cells develop and express IL-12R and IL-18R in the absence of IL-12 or IL-18, and that both IL-18 and IL-12 directly and independently augment perforin-mediated cytotoxic activity of NK cells.

IL-12 up-regulates IL-18 receptor expression on T cells, Th1 cells, and B cells: synergism with IL-18 for IFN-gamma production

IL-18 is a product of macrophages and with IL-12 strikingly induces IFN-gamma production from T, B, and NK cells. Furthermore, IL-18 and 1L-12 synergize for IFN-gamma production from Th1 cells, although this combination fails to affect Th2 cells. In this study, we show that IL-12 and IL-18 promptly and synergistically induce T and B cells to develop into IFN-gamma-producing cells without engaging their Ag receptors. We also studied the mechanism underlying differences in IL-18 responsiveness between Th1 and Th2 cells. Pretreatment of T or B cells with IL-12 rendered them responsive to IL-18, which induces cell proliferation and IFN-gamma production. These IL-12-stimulated cells had both high and low affinity IL-18R and an increased IL-18R mRNA expression. In particular, IL-12-stimulated T cells strongly and continuously expressed IL-18R mRNA. However, when T cells developed into Th1 cells after stimulation with anti-CD3 and IL-12, they lowered this IL-12-induced-IL-18R mRNA expression. Then, such T cells showed a dominant response to anti-CD3 by IFN-gamma production when they were subsequently stimulated with anti-CD3 and IL-18. In contrast, Th2 cells did not express IL-18R mRNA and failed to produce IFN-gamma in response to anti-CD3 and IL-18, although they produced a substantial amount of IFN-gamma in response to anti-CD3 and IL-12. However, when Th1 and Th2 cells were stimulated with anti-CD3, IL-12, and IL-18, only the Th1 cells markedly augmented IFN-gamma production in response to IL-18, suggesting that IL-18 responsiveness between Th1 and Th2 cells resulted from their differential expression of IL-18R.

[IL-18 and IL-18 receptor]

Interleukin-18 (IL-18) is a recently cloned cytokine, produced from activated macrophages, including Kupffer cells. IL-18 is originally called interferon-gamma inducing factor (IGIF), due to its action to induce IFN-gamma production from Th 1 cells and NK cells. However, recent studies suggested that, IL-18 also enhances expression of FasL and NK activity as well as GM-CSF production. These data revealed this novel cytokine is pleiotropic. Recently, cDNA encoding human IL-18 receptor (IL-18R) was cloned. And, we had cloned murine IL-18R cDNA by RT-PCR, using human IL-18R sequence. Northern blot analysis of cytoplasmic RNA from T cells stimulated with IL-12 clearly demonstrated that, T cells stimulated with IL-12 induced high level of IL-18R-mRNA, whereas non-stimulated T cells did not have. Interestingly, we had several reports, indicated the involvement of IL-18 on the progressions of pathogenicity in chronic inflammatory diseases, including endotoxin-shock, hepatitis and autoimmune-diabetes. We need further studies to reveal physiological roles of this novel cytokine in various inflammatory or autoimmune diseases.

Regulation of interferon-gamma production by IL-12 and IL-18

IL-18 (interferon-inducing factor) and IL-12 exhibit a marked synergism in interferon-gamma induction in T cells. Investigations into the mechanism of this synergism have revealed that IL-12 upregulates expression of the IL-18 receptor on cells producing interferon-gamma. Although IL-18 does not induce the development of Th1 cells, it is essential for the effective induction and activation of Th1 cells by IL-12. As for natural killer cells, IL-18 seems to activate them independently of IL-12. Although IL-12 and IL-18 activate both innate and acquired immunity, their excessive production by activated macrophages may induce multiple organ disorders including disruption of the immune system.

IL-4 and anti-CD40 protect against Fas-mediated B cell apoptosis and induce B cell growth and differentiation

Most Th2 clones, when activated, produce IL-4 and express CD40 ligand (CD40L) on their cell surface. Therefore, they can induce growth and differentiation of B cells by cognate help. In contrast, activated Th1 clones, which produce IFN-gamma and express both CD40L and Fas ligand (FasL) on their cell surface, often induce B cell apoptotic cell death. To understand the mechanism by which Th2 cells can induce B cell growth and differentiation in the presence of FasL-positive cells, we stimulated B cells with IL-4, anti-IgM and/or anti-CD40 in the presence of anti-Fas. We report here that addition of anti-Fas strongly inhibited anti-CD40-induced B cell proliferation without affecting anti-IgM-induced B cell proliferation. Furthermore we showed that stimulation of B cells with anti-CD40 induced the expression of Fas molecules on the B cells (approximately 30%) and rendered them highly sensitive to anti-Fas-mediated apoptotic cell death. Indeed, over 23% of anti-CD40-stimulated B cells showed hypodiploid DNA after being incubated with anti-Fas, while h2 cells could dominate over FasL-positive Th1 cells by production of CD40L and IL-4, which in combination induce antibody production and inhibit the Th1 cell-mediated immune response.

Essential role of Stat6 in IL-4 signalling

Interleukin-4 (IL-4) is a pleiotropic lymphokine which plays an important role in the immune system. IL-4 activates two distinct signalling pathways through tyrosine phosphorylation of Stat6, a signal transducer and activator of transcription, and of a 170K protein called 4PS. To investigate the functional role of Stat6 in IL-4 signalling, we generated mice deficient in Stat6 by gene targeting. We report here that in the mutant mice, expression of CD23 and major histocompatibility complex (MHC) class II in resting B cells was not enhanced in response to IL-4. IL-4 induced B-cell proliferation costimulated by anti-IgM antibody was abolished. The T-cell proliferative response was also notably reduced. Furthermore, production of Th2 cytokines from T cells as well as IgE and IgG1 responses after nematode infection were profoundly reduced. These findings agreed with those obtained in IL-4 deficient mice or using antibodies to IL-4 and the IL-4 receptor. We conclude that Stat6 plays a central role in exerting IL-4 mediated biological responses.

Identification and characterization of IL-2 hyper-responsive NZB/WF1 CD5- B cells

The responsiveness of CD5- and CD5+ B cells of BALB/c and NZB/WF1 mice to various cytokines was examined with respect to their growth and differentiation. BALB/c splenic CD5- B cells required longer incubation with IL-2 or pretreatment with IL-4 to respond to IL-2 by DNA synthesis, whereas NZB/WF1 CD5- B cells were highly competent to IL-2. Flow cytometric analysis demonstrated that NZB/WF1 and BALB/c CD5- B cells had higher and intermediate proportions of B cells positive for IL-2R beta, respectively. On the other hand, BALB/c and NZB/WF1 splenic CD5+ B cells consisted of lower proportion of B cells positive for IL-2R beta than did their corresponding CD5- B cells and grew meagerly in response to IL-2. Peritoneal exudative CD5+ B cells of NZB/WF1 mice lacked IL-2R beta mRNA expression and failed to respond to IL-2. Although both BALB/c and NZB/WF1 CD5- B cells pretreated with anti-IgM, IL-4, and IL-5 responded to IL-2 by DNA synthesis, only BALB/c CD5- B cells developed into IgM-producing cells. Furthermore, BALB/c, but not NZB/WF1 CD5-, B cells pretreated with anti-IgM and IL-5 responded to IL-2 by IgM production without DNA synthesis. Thus, cross-talk between IL-4 and IL-2 operated in the growth responses of both BALB/c and NZB/WF1 splenic CD5- B cells, whereas cross-talk between IL-5 and IL-2 operated only in the differentiation of BALB/c CD5- B cells, providing us with another intriguing functional abnormality of NZB/WF1 B cells.

Identification and characterization of IL-2 hyper-responsive NZB/WF1 CD5- B cells

The responsiveness of CD5- and CD5+ B cells of BALB/c and NZB/WF1 mice to various cytokines was examined with respect to their growth and differentiation. BALB/c splenic CD5- B cells required longer incubation with IL-2 or pretreatment with IL-4 to respond to IL-2 by DNA synthesis, whereas NZB/WF1 CD5- B cells were highly competent to IL-2. Flow cytometric analysis demonstrated that NZB/WF1 and BALB/c CD5- B cells had higher and intermediate proportions of B cells positive for IL-2R beta, respectively. On the other hand, BALB/c and NZB/WF1 splenic CD5+ B cells consisted of lower proportion of B cells positive for IL-2R beta than did their corresponding CD5- B cells and grew meagerly in response to IL-2. Peritoneal exudative CD5+ B cells of NZB/WF1 mice lacked IL-2R beta mRNA expression and failed to respond to IL-2. Although both BALB/c and NZB/WF1 CD5- B cells pretreated with anti-IgM, IL-4, and IL-5 responded to IL-2 by DNA synthesis, only BALB/c CD5- B cells developed into IgM-producing cells. Furthermore, BALB/c, but not NZB/WF1 CD5-, B cells pretreated with anti-IgM and IL-5 responded to IL-2 by IgM production without DNA synthesis. Thus, cross-talk between IL-4 and IL-2 operated in the growth responses of both BALB/c and NZB/WF1 splenic CD5- B cells, whereas cross-talk between IL-5 and IL-2 operated only in the differentiation of BALB/c CD5- B cells, providing us with another intriguing functional abnormality of NZB/WF1 B cells.

[Interleukin-4 (IL-4)]

Helper T cells can be divided into Th1 type cell which produces IL-2 and IFN-gamma and Th2 type cell which produces IL-4, IL-5, and IL-6. In general, cytokine has a pleiotropic action. Furthermore cytokines have redundancy in their action. IL-4 is a major product of Th 2 type cell and is an essential cytokine for IgE production, which is also induced by recently found IL-13. Additionally IL-4 is a key factor for the development of Th2 cell, which produces cytokines responsible for inducing allergic reaction. In this paper, we described the gene regulation, molecular structure and biological action including the anti-tumor activity of IL-4.

Structure of the murine mb-1 gene encoding a putative sIgM-associated molecule

Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3'-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5'-flanking region has sequence stretches homologous to IgVH 5'-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgVH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3'-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.

Structure of the murine mb-1 gene encoding a putative sIgM-associated molecule

Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3'-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5'-flanking region has sequence stretches homologous to IgVH 5'-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgVH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3'-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.

B lymphocyte lineage-restricted expression of mb-1, a gene with CD3-like structural properties

A gene, called m-mb-1, was isolated from a murine pre-B-minus T lymphocyte subtracted library. It was found expressed as mRNA at low to medium abundance in early progenitors of the B lineage, in pre-B and mature B lineage cell lines, in normal resting B lymphocytes and in polyclonally activated B cell blasts. The gene was not expressed in plasmacytomas, in cell lines of the monocyte/macrophage, the T lymphocyte or the fibroblast lineages, nor in thymus, liver, heart, kidney, lung or brain. The nucleotide sequence of the m-mb-1 gene encodes a putative membrane glycoprotein with 220 amino acids, which includes a leader sequence, a putative extracellular domain with two potential N-glycosylation sites, a transmembrane portion and a putative intracellular domain. The partial sequence of a human homologue, h-mb-1, shows nearly 90% homology in nucleotide as well as amino acid sequences to the murine form of a stretch of the putative intracytoplasmic domain. Antibodies raised against a fusion protein of m-mb-1 with protein A, affinity purified for their m-mb-1 specificity, stained pre-B and mature B cell lines on their surface, but did not stain T cell lines and fibroblasts. Antibodies raised against a stretch of 20 amino acids of the putative intracellular domain with 90% homology between the mouse and human protein did not stain the surface of any cell lines tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Complementary DNA for a novel human interleukin (BSF-2) that induces B lymphocytes to produce immunoglobulin

When stimulated with antigen, B cells are influenced by T cells to proliferate and differentiate into antibody-forming cells. Since it was reported that soluble factors could replace certain functions of helper T cells in the antibody response, several different kinds of lymphokines and monokines have been reported in B-cell growth and differentiation. Among these, human B-cell differentiation factor (BCDF or BSF-2) has been shown to induce the final maturation of B cells into immunoglobulin-secreting cells. BSF-2 was purified to homogeneity and its partial NH2-terminal amino-acid sequence was determined. These studies indicated that BSF-2 is functionally and structurally unlike other known proteins. Here, we report the molecular cloning, structural analysis and functional expression of the cDNA encoding human BSF-2. The primary sequence of BSF-2 deduced from the cDNA reveals that BSF-2 is a novel interleukin consisting of 184 amino acids.

Functional expression of a microinjected Ed alpha gene in C57BL/6 transgenic mice

The class II major histocompatibility antigens, I-A and I-E, have been detected on the surface of certain immunocompetent cells, including B lymphocytes and monocytes. These molecules are involved in cell-cell interactions in the immune responses. Each class II antigen consists of two subunits, alpha and beta chains, and the genes encoding these subunits have been well characterized at the molecular level. To analyse the regulatory mechanism of E alpha gene expression and the role of the I-E antigen in the regulation of the immune responses, we have produced transgenic mice by microinjecting cloned Ed alpha genes into fertilized eggs of C57BL/6 mice of b haplotype. This strain of mouse carries a deletion in the upstream (5') region of the E alpha gene covering the transcriptional promoter and, therefore, does not express this gene. Interestingly, this genetic defect of the E alpha gene is accompanied by the inability of the host mouse to respond to a certain set of antigens, phenomena generally termed Ir gene control. We report here that the Ed alpha genes are expressed in these transgenic mice to form the I-Ed alpha Eb beta antigen on the surface of B lymphocytes and monocytes and that these I-E antigens are functional in terms of the induction of a mixed lymphocyte reaction and the restoration of immune responsiveness to poly(L-glutamic acid-L-lysine-L-phenylalanine) (GL-Phe).

A T15-idiotype-positive T suppressor hybridoma does not use the T15 VH gene segment

The T suppressive factor (TsF) released from a T15-idiotype-positive phosphocholine (PCho)-specific T hybridoma, F18-3-4, which was formed by fusion between BALB/c T cells and BW5147 thymoma, was immunochemically characterized. TsF inhibited the in vitro induction of both IgE and IgG1 antibody responses of 2,4-dinitrophenyl keyhole limpet hemocyanin (DNP-KLH)-primed spleen cells in the presence of PCho-KLH-DNP. TsF had the ability to bind to PCho determinants and possessed T15 idiotype determinants as well as Iad products. However, we were unable to detect either the rearrangement of the T15 VH gene or the presence of T15 VH gene transcripts in hybridomas by DNA and RNA blot hybridization analyses with the T15 VH DNA probe.