Expression of human and mouse genes encoding polkappa: testis-specific developmental regulation and AhR-dependent inducible transcription

BACKGROUND

Human polkappa is a newly identified low-fidelity DNA polymerase. While the enzyme bypasses an abasic site and acetylaminofluorene-adduct in an error-prone manner, it bypasses benzo[a]pyrene-N2-dG lesions in a mostly error-free manner by incorporating predominantly dC opposite the bulky lesions. Benzo[a]pyrene (B[a]P) is activated through intracellular process mediated by the arylhydrocarbon receptor (AhR, also called the dioxin receptor), which is a ligand-activated transcription factor with high affinities for aromatic compounds such as B[a]P and dioxin.

RESULTS

We examined promoter structures of the human POLK and mouse Polk genes to study how their expressions are regulated. The mouse Polk gene is developmentally regulated in testis and utilizes two transcription start sites during spermatogenesis, while it utilizes only one site in tissues other than testis. Both of the mouse Polk and the human POLK genes have two AhR-binding sites in the promoter regions and the expression of the mouse Polk gene is indeed enhanced upon AhR-activation.

CONCLUSIONS

The AhR activation increases expression of the mouse Polk gene and probably the human POLK gene, the product of which bypasses benzo[a]pyrene-N2-dG lesions in a mostly accurate manner. Thus, polkappa seems to function to reduce mutagenesis at benzo[a]pyrene-adducts, although it may also have a role related to spermatogenesis.

[Comparative antibacterial activity of carbapenems against P. aeruginosa (1)]

Comparative antibacterial activity of imipenem (IPM), panipenem (PAPM), meropenem (MEPM) and biapenem (BIPM) was determined against 288 clinical isolates of P. aeruginosa collected from various hospitals in 2000. The order of activity by comparison of MIC50/MIC80/MIC90 was: MEPM (1/4/8 micrograms/ml) > BIPM (1/4/16 micrograms/ml) > IPM (2/4/16 micrograms/ml) > PAPM (8/16/32 micrograms/ml). Moreover, the order of activity against 75 strains of P. aeruginosa (MIC of CAZ, AZT was > or = 16 micrograms/ml and MIC of IPM, MEPM was < or = 8 micrograms/ml) by comparison of MIC50/MIC80/MIC90 was: BIPM (1/2/8 micrograms/ml) > or = MEPM (1/4/8 micrograms/ml) > or = IPM (2/2/8 micrograms/ml) > PAPM (8/16/16 micrograms/ml). Judging from both correlation between the MICs of carbapenems and relationship between class C beta-lactamase activity and drug susceptibility of carbapenems, it becomes apparent that carbapenems, especially BIPM and MEPM will be useful for treatment of antipseudomonal cephem resistant pseudomonas infection.

Use of secondarily revised VH genes in IgE antibodies produced in mice infected with the nematode Nippostrongylus brasiliensis

Although a high level of IgE is produced after primary infection with Nippostrongylus brasiliensis (Nb), most of the IgE antibodies (Abs) are not specific to the worm. Analyses with Western blotting and enzyme-linked immunosorbent assay (ELISA) revealed that the IgE Abs from Nb-infected BALB/c mice did not show reactivity with Nb-derived excretory-secretory proteins (NES) and antigens present in the cell-free extracts of the worm. Monoclonal IgE Abs obtained from the Nb-infected mice were not reactive with these Nb antigen either. To characterize Nb-induced IgE response, we used (QM x C57BL/6)F1 (QBF1) mice that bear the knock-in 17.2.25 VHDJH segment (VHT) encoding a VH region specific to 4-hydroxy-3-nitrophenylacetyl hapten, and express VHT-encoded antigen receptors on 80-85% of their B cells. Consistent with the frequency of VHT-positive B cells, more than 80% of IgE Abs induced in QBF1 B cells that were cultured with LPS plus IL-4 were found to bear VHT-encoded H chains. In contrast, when QBF1 mice were infected with Nb, less than 10% of Nb-induced IgE Abs were found to use VHT. The QBF1-derived IgE did not react with Nb antigens either. Taken together, data suggest that Nb-induced IgE response in mice is not merely the result of polyclonal activation of B cells, but may involve a mechanism that revises Ig genes secondarily.

Restoration of immunocyte functions by thymosin alpha1 in cyclophosphamide-induced immunodeficient mice

Thymosin alpha1 (Talpha1) is an oligopeptide hormone originally isolated from the thymus gland, and has been reported to have stimulating effects on the differentiation of T cells and NK cells. These immunostimulating properties have been considered to be useful for improving immune disorders associated with various diseases including cancer, AIDS and hepatitis. Here, we characterized immunostimulating properties of Talpha1 in experimental immunodeficiency of mice that was induced by the administration of cyclophosphamide (CY). Repeated injection of 30-300 microg/kg/day of Talpha1 after CY-treatment significantly accelerated the restoration of the reduced number of CD4+CD8+ T cells in the thymus. Talpha1 administration was effective in restoring the suppressed activities of helper T cells and cytotoxic T cells in CY-treated mice. Talpha1 also had stimulating effects on reduced activity of lymphokine-activated killer cells in CY-treated mice. These results indicate that Talpha1 is stimulatory for both humoral and cellular immune responses, thus providing the immunological basis for the clinical benefit of this compound.

Prevention of collagen-induced arthritis in DBA/1 mice by oral administration of AZ-9, a bacterial polysaccharide from Klebsiella oxytoca

Collagen-induced arthritis (CIA) is an excellent model of rheumatoid arthritis (RA) in humans that is induced in DBA/1 mice immunized with bovine type II collagen (CII). Here, we report that the induction of CIA was effectively suppressed by oral administration of AZ-9, a purified polysaccharide with the average molecular weight of approximately 200 kDa that was produced by a soil bacterium, Klebsiella oxytoca. When AZ-9 was administered at 125-250 mg/kg/day orally for 9 consecutive days after immunization with CII followed by its administration every 3 days, resulted in a marked reduction of the incidence and the severity of CIA. The serum level of anti-CII IgG2a and the production of IFN-gamma and IL-12 in the draining lymph node (LN) cells were significantly lower in AZ-9-administered mice than the untreated control. These findings suggest that orally administered AZ-9 suppressed CIA through attenuating a Th1-type response to CII. AZ-9 could be fragmented into smaller molecules (3-4 kDa) without losing its suppressive activity.

In vitro plasma protein binding and cellular uptake of ATX-S10(Na), a hydrophilic chlorin photosensitizer

ATX-S10(Na), a hydrophilic chlorin photosensitizer having an absorption maximum at 670 nm, is a candidate second-generation photosensitizer for photodynamic therapy (PDT) for cancer treatment. In this study, we examined plasma protein binding, cellular uptake and subcellular targets of ATX-S10(Na) in vitro. Protein binding ratios of 50 microg / ml ATX-S10(Na) in rat, dog and human plasma were 73.0%, 87.2% and 97.7%, respectively. Gel filtration chromatography revealed that 1 mg / ml ATX-S10(Na) bound mainly to high-density lipoprotein (HDL) and serum albumin at the protein concentration of 0.4%, with binding ratios of 46% and 36%, respectively. The free form of ATX-S10(Na) was mostly incorporated into T.Tn cells, and its cellular uptake was partially but significantly inhibited by endocytosis inhibitors such as phenylarsine oxide, chloroquine, monensin and phenylglyoxal, and by chilling the cells to 4 degrees C. However, ouabain, harmaline, sodium cyanide, probenecid and aspartic acid did not influence the uptake of ATX-S10(Na), suggesting that cellular uptake of ATX-S10(Na) was not related to sodium-potassium pump activity, sodium-dependent transporter activity, mitochondrial oxidative respiration, organic anion transporter activity or aspartic acid transporter activity. By fluorescence microscopy, lysosomal localization of ATX-S10(Na) was observed in T.Tn cells. However, electron microscopic observation revealed that many subcellular organelles such as mitochondria, endoplasmic reticulum, ribosomes, Golgi complex and plasma membrane were damaged by PDT using 25 microg / ml ATX-S10(Na) soon after laser irradiation at 50 J / cm(2), and tumor necrosis was rapidly induced. This result indicated that ATX-S10(Na) was widely distributed within the cell.

Photodynamic therapy for experimental tumors using ATX-S10(Na), a hydrophilic chlorin photosensitizer, and diode laser

ATX-S10(Na), a hydrophilic chlorin photosensitizer having an absorption maximum at 670 nm, is a candidate second-generation photosensitizer for use in photodynamic therapy (PDT) for cancer treatment. The effectiveness of PDT using ATX-S10(Na) and a diode laser for experimental tumors was evaluated in vitro and in vivo. In-vitro PDT using ATX-S10(Na) and the diode laser showed drug concentration-, laser dose- and drug exposure time-dependent cytotoxicity to various human and mouse tumor cell lines. In Meth-A sarcoma-implanted mice, optimal PDT conditions were found where tumors were completely eliminated without any toxicity. Against human tumor xenografts in nude mice, the combined use of 5 mg / kg ATX-S10(Na) and 200 J / cm(2) laser irradiation 3 h after ATX-S10(Na) administration showed excellent anti-tumor activity, and its efficacy was almost the same as that of PDT using 20 mg / kg porfimer sodium and a 100 J / cm(2) excimer dye laser 48 h after porfimer sodium injection. Microscopic observation of tumor tissues revealed that PDT using ATX-S10(Na) and the diode laser induced congestion, thrombus and degeneration of endothelial cells in tumor vessels, indicating that a vascular shutdown effect plays an important role in the anti-tumor activity of PDT using ATX-S10(Na) and the diode laser.

Selective augmenting effects of nitric oxide on antigen-specific IgE response in mice

Here, we report the enhancing effects of nitric oxide (NO) on an IgE antibody response in mice. Anti-trinitrophenyl (TNP) IgE production induced in vitro in TNP keyhole limpet hemocyanin (KLH)-primed spleen cells was inhibited by approximately 70% when an NO synthase (NOS) inhibitor, L-N(G)-monomethyl-L-arginine, was added at 10(-7)-10(-6) M to the lymphocyte culture. On the other hand, addition of NO-generating agents to the culture resulted in a marked enhancement of the IgE production. In contrast, anti-TNP IgM and IgG1 responses were affected only marginally when the IgE production was either suppressed or augmented by these agents. NO did not directly augment IgE class switching in normal B cells stimulated with lipopolysaccharide and interleukin (IL)-4. NO-mediated augmentation of the IgE response is considered to be of a physiological significance because administration of aminoguanidine (AG), an inhibitor of inducible NOS, to immunized mice resulted in a preferential suppression of anti-TNP IgE production in vivo. This may be explained by the observation that AG-administration increased interferon-gamma expression without changing that of IL-4 in the immunized mice. Taken together, these observations suggest a pathophysiological role of NO in the development of IgE-mediated allergic diseases.

In vitro antibacterial activity of LJC 11,036, an active metabolite of L-084, a new oral carbapenem antibiotic with potent antipneumococcal activity

LJC 11,036 is the active metabolite of L-084, a novel oral carbapenem that exhibits potent broad-spectrum activity. Antibacterial activities of LJC 11,036 against clinical isolates from respiratory infections, such as Streptococcus pneumoniae (n = 52), Streptococcus pyogenes (n = 19), Haemophilus influenzae (n = 50), Klebsiella pneumoniae (n = 53), and Moraxella catarrhalis (n = 53), and from urinary-tract infections, such as Escherichia coli (n = 53) (MICs at which 90% of the isolates were inhibited [MIC(90)s], 0.1, </=0.006, 0.39, 0.05, 0.05, and 0.05 microg/ml, respectively), were 2- to 64-fold higher than those of imipenem, cefdinir, and faropenem. Moreover, against these bacterial species, except for H. influenzae, the MIC(90)s of LJC 11,036 were 4- to 512-fold lower than those of levofloxacin. LJC 11,036 showed bactericidal activity equal or superior to that of imipenem. Bactericidal activity against penicillin-resistant S. pneumoniae (PRSP) did not vary with the phase of growth. LJC 11,036 had potent activity against various beta-lactamase-producing strains, excluding carbapenemase producers. Against renal dehydropeptidase-I, LJC 11,036 was more stable than imipenem. Furthermore, LJC 11,036 produced in vitro postantibiotic sub-MIC effects against PRSP HSC-3 (6.0 h at one-fourth the MIC) and H. influenzae LJ5 (9.2 h at one-half the MIC). LJC 11,036 showed high binding affinities for PBP1A, -1B, -2A/2X, -2B, and -3 of PRSP and for PBP1B, -2, -3A, and -3B of H. influenzae.

IL-4-dependent IgE class switching in an anti-trinitrophenyl B-cell hybridoma after engagement of antigen receptors

A B-cell hybridoma, TP67.21 that expresses surface anti-trinitrophenyl (TNP) IgM but does not secrete the antibody spontaneously has been reported to differentiate into anti-TNP IgM-secreting cells in response to lipopolysaccharide or engagement of surface IgM. Here, we report isolation and characterization of a subclone, TP67.21E (TP.E) that undergoes isotype switching to IgE in an interleukin (IL)-4-dependent manner. TP.E cells secreted anti-TNP IgE depending on exogenous IL-4 when they were cultured with an anti-IgM antibody for 6-8 days. 8-Mercaptoguanosine, which has been shown to enhance IgE class switching in murine splenic B-cells further augmented the IgE response in TP.E cells. Immunofluorescence microscopy revealed that approximately 1.2% of the cultured cells became positive for intracellular IgE after the stimulation culture. The germline epsilon transcripts were expressed transiently on days 2-4 of the culture, while expression of the productive epsilon transcripts was induced 5 days after the start of the culture, thus suggesting that IgE class switching occurred in TP.E cells under these conditions.

Expression of recombination activating genes in germinal center B cells: involvement of interleukin 7 (IL-7) and the IL-7 receptor

Mouse germinal center (GC) B cells have been shown to undergo secondary V(D)J (V, variable; D, diversity; J, joining) recombination (receptor editing) mediated by the reexpressed products of recombination activating gene (RAG)-1 and RAG-2. We show here that interleukin (IL)-7 as well as IL-4 was effective in inducing functional RAG products in mouse IgD+ B cells activated via CD40 in vitro. Blocking of the IL-7 receptor (IL-7R) by injecting an anti- IL-7R monoclonal antibody resulted in a marked suppression of the reexpression of RAG-2 and subsequent V(D)J recombination in the draining lymph node of immunized mice, whereas RAG-2 expression was not impaired in immunized IL-4-deficient mice. Further, these peripheral B cells activated in vitro or in vivo were found to express IL-7R. These findings indicate a novel role for IL-7 and IL-7R in inducing receptor editing in GC B cells.

Expression and function of recombination activating genes in mature B cells

Recombination activating genes, RAG-1 and RAG-2, encode proteins that catalyze the rearrangement of immunoglobulin genes in B cells and T cell receptor genes in T cells to generate the diversity of these important recognition molecules in immune system. It has been believed that these gene rearrangements occur exclusively in premature stages of B and T lymphocytes, consistent with the observation that RAG expression is downregulated in mature lymphocytes. However, recent studies have revealed that even mature B cells in peripheral lymphoid tissues can reexpress RAG-1 and RAG-2 proteins following immunization. Strikingly, RAG-expressing B cells are localized in the germinal centers (GCs) of secondary lymphoid tissues in which somatic hypermutations, isotype switching, and affinity maturation of antibodies take place. Recently, it has been shown that RAG proteins thus induced are functional and can mediate the secondary rearrangement of Ig genes (receptor editing) at mature stages of B cells. Evidence is accumulating suggesting that GCs are regarded as a primary lymphoid tissue. In the present review, we briefly summarize recent advances in the expression and the characterization of RAG proteins and discuss their possible role in mature B cells in relation to the diversification and the selection of B cell repertoire in GCs.

Rearrangement of lambda light chain genes in mature B cells in vitro and in vivo. Function of reexpressed recombination-activating gene (RAG) products

V(D)J (V, variable; D, diversity; J, joining) combination of immunoglobulin (Ig) genes established in premature B cells has been thought to be conserved throughout differentiation at mature stages. However, germinal center (GC) B cells have been shown to reexpress recombination-activating gene (RAG)-1 and RAG-2 proteins in immunized mice. Here, we present several lines of evidence indicating that RAG proteins thus induced are functional as the V(D)J recombinase. DNA excision product reflecting Vlambda1 to Jlambda1 rearrangement was generated in parallel with the expression of RAG genes in mature mouse B cells that were activated in vitro with LPS and IL-4. Similar lambda chain gene rearrangement was observed in the draining lymph node of immunized mice. Further, B cells that underwent lambda gene rearrangement were shown by in situ PCR to be localized within GCs. Thus, secondary rearrangement of Ig genes (receptor editing) can occur in mature B cells.

Characterization of ASK mice, a strain highly sensitive to anaphylactic shock

A mouse strain named ASK that was originally isolated from El (epilepsy) mice has been shown to be highly sensitive to anaphylactic shock. Here, we characterized the bases of the sensitivity of ASK mice in comparison with the parental strain, El. More than 90% of ASK mice, but not El mice that had been sensitized either actively or passively, died within 1 h following an antigen challenge. The anaphylactic death was effectively blocked by diphenhydramine. Plasma histamine levels increased by 30-50 fold in ASK after the antigen challenge, but only a 2-3-fold increase was observed in El mice. All (El x ASK) F1 mice, either male or female, showed an ASK-like phenotype, suggesting that the impaired plasma histamine response in El mice is due to some recessive mutation(s). Consistent with the plasma histamine responses, cultured mast cells derived from El bone marrow showed impaired potency to degranulate in response to surface IgE engagement, in contrast to ASK mast cells which undergo normal degranulation. Another characteristic feature of ASK mice is their sensitivity to histamine, since 75% of the mice were killed by the subcutaneous administration of 100-200 mg/kg histamine, while C3H and BALB/c mice were resistant to even 600 mg/kg histamine. Taken together, the major bases of the susceptibility to anaphylactic shock in ASK mice are thought to be the enhanced sensitivity to histamine and the recovered degranulation machinery in mast cells that is impaired in El mice.

Characterization of B cells expressing recombination activating genes in germinal centers of immunized mouse lymph nodes

Products of recombination activating genes (RAG-1 and RAG-2) involved in the rearrangement of Ig genes have been shown to be expressed only in immature stages of B cells. However, we have recently found that RAG genes were re-expressed in mature mouse B cells activated in vitro and in germinal centers (GCs) of immunized mouse lymph nodes (LNs). Here, we report that RAG transcripts and their proteins were expressed in parallel with the formation of GCs in popliteal LNs from mice immunized in the hind footpads. Immunocytochemical analysis revealed that RAG+ B cells were localized within GCs and were present as apoptotic tingible body cells. RAG expression is not considered a nonspecific result of apoptosis, since apoptotic B cells generated by surface Ig-engagement did not express RAG genes. These results suggest a novel role of RAG products in the differentiation of B cells in GCs.

Characterization of B cells expressing recombination activating genes in germinal centers of immunized mouse lymph nodes

Products of recombination activating genes (RAG-1 and RAG-2) involved in the rearrangement of Ig genes have been shown to be expressed only in immature stages of B cells. However, we have recently found that RAG genes were re-expressed in mature mouse B cells activated in vitro and in germinal centers (GCs) of immunized mouse lymph nodes (LNs). Here, we report that RAG transcripts and their proteins were expressed in parallel with the formation of GCs in popliteal LNs from mice immunized in the hind footpads. Immunocytochemical analysis revealed that RAG+ B cells were localized within GCs and were present as apoptotic tingible body cells. RAG expression is not considered a nonspecific result of apoptosis, since apoptotic B cells generated by surface Ig-engagement did not express RAG genes. These results suggest a novel role of RAG products in the differentiation of B cells in GCs.

Molecular cloning of a novel murine cell-surface glycoprotein homologous to killer cell inhibitory receptors

We have isolated a cDNA clone encoding a novel murine cell-surface glycoprotein. This polypeptide is predicted to be composed of a signal peptide of 23 amino acids, an extracellular region of 620 amino acids that contains six immunoglobulin-like domains with five potential N-glycosylation sites, a transmembrane sequence of 20 amino acids, and a cytoplasmic tail of 178 amino acids with four sets of sequences similar to the immunoreceptor tyrosine-based inhibition motif. The relative molecular mass of the mature polypeptide is calculated to be 90,520 Da. The polypeptide, designated as p91, shows striking homologies to human killer cell inhibitory receptors, a murine gp49B1 protein, a bovine Fcgamma2 receptor, and a human Fcalpha receptor. The mRNA of p91 was especially abundant in murine macrophages. Western blot analysis using p91-specific anti-peptide sera detected a 130-kDa polypeptide in macrophages. Surface biotinylation and immunoprecipitation analysis verified the surface expression of the translation products on COS-1 cells transfected with the p91 cDNA, but the cells failed to show any Fc binding activity.

Reexpression of RAG-1 and RAG-2 genes in activated mature mouse B cells

Recombination activating genes (RAG-1 and RAG-2), involved in V(D)J rearrangement of immunoglobulin genes, have been thought to be expressed only in immature stages of B-cell development. However, RAG-1 and RAG-2 transcripts were found to be reexpressed in mature mouse B cells after culture with interleukin-4 in association with several different co-stimuli. Reexpression was also detected in draining lymph nodes from immunized mice. RAG-1 and RAG-2 proteins could be detected by immunofluorescence microscopy in the nuclei of B cells cultured in vitro and in the germinal centers of draining lymph nodes. These findings suggest that RAG gene products play a heretofore unsuspected role in mature B cells.

Suppression of in vitro cellular immune response by nitrogen-containing terpene alcohol derivatives

A series of nitrogen-containing terpene alcohol derivatives were tested for their immunosuppressive effects in vitro, and KYKC-407 (erythro-1-(1-imidazolyl)-3,7,11-trimethyl-dodecane-2(S),3(R)-diol) was found to be the most effective in suppressing the induction of cytotoxic T cell (CTL) activity. CTL induction in the coculture of C3H spleen cells with mitomycin C-treated BALB/c spleen cells was suppressed by more than 90% when 4 microM KYKC-407 was added to the culture. Under these conditions, lymphocyte proliferation was also suppressed to a similar extent by this compound. Flow cytometric analysis revealed that KYKC-407 strongly inhibited the proliferation of CD8+ T cell subset, but showed less suppressive effects on CD4+ T cells. In contrast to cyclosporin A, KYKC-407 at 1-4 microM did not inhibit the proliferative response to concanavalin A. Further, KYKC-407 suppressed CTL induction even in the presence of exogenous IL-2, thus suggesting that the compound does not exert its effects through inhibiting IL-2 production.

Subconjunctival immunization of mice for inducing IgE antibody response in parotic lymph node

Subconjunctival immunization of mice with dinitrophenyl (DNP)-Ascaris plus alum led to the induction of a local anti-DNP IgE response in 8 days. Anti-DNP IgE was found to be secreted from isolated lymphocytes in the parotic lymph node neighboring the immunization site but not from those in the spleen and the mesenteric lymph node. The IgE response was also confirmed by the detection of C epsilon transcript in the parotic lymph node cells. Ocular topical application of betamethazone resulted in considerable suppression of the IgE response in the parotic lymph node, thus suggesting that this immunization protocol is useful for evaluating ocular topical anti-allergic drugs that are expected to suppress local IgE responses.

Requirements of a costimulus for IL-4-induced IgE class switching in murine B cells activated via antigen receptors: effectiveness of 8-mercaptoguanosine

In the present paper, we investigated the requirements for the induction of IgE responses in murine B cells stimulated via surface Ig receptors by trinitrophenyl (TNP)-LPS or F(ab')2 of anti-mouse IgM (anti-mu) Abs. When murine B cells were cultured with 0.2 microgram/ml TNP-LPS, the secretion of anti-TNP IgM, but not that of IgG1 or IgE, was induced. It should be noted that IL-4, alone or in combination with IL-2 or IL-5, was not sufficient for inducing IgE class switching in these B cells, in contrast to the cells activated polyclonally with 20 micrograms/ml LPS, suggesting that an additional signal is required under the former conditions. After extensive screening of costimuli for inducing IgE in cooperation with IL-4, we found that 8-mercaptoguanosine (8-SGuo), a potent B cell activator, was effective. The addition of 8-SGuo to TNP-LPS-stimulated B cell cultures resulted in the secretion of both anti-TNP IgM and IgG1, but not anti-TNP IgE. Anti-TNP IgE formation was induced only when 8-SGuo was added in combination with IL-4, whereas 8-SGuo plus IL-4 failed to induce IgE secretion in the absence of TNP-LPS. Similar requirements for 8-SGuo and IL-4 for IgE formation were observed when B cells were stimulated with anti-mu. It was revealed that induction of the IgE responses was accompanied by increased frequency of surface IgE+ B cells and the expression of germline and productive epsilon transcripts. In B cells stimulated with anti-mu plus IL-4, 8-SGuo was shown to enhance the expression of the B cell-specific activator protein gene that is thought to be required in IL-4-dependent germline epsilon transcription.

Requirements of a costimulus for IL-4-induced IgE class switching in murine B cells activated via antigen receptors: effectiveness of 8-mercaptoguanosine

In the present paper, we investigated the requirements for the induction of IgE responses in murine B cells stimulated via surface Ig receptors by trinitrophenyl (TNP)-LPS or F(ab')2 of anti-mouse IgM (anti-mu) Abs. When murine B cells were cultured with 0.2 microgram/ml TNP-LPS, the secretion of anti-TNP IgM, but not that of IgG1 or IgE, was induced. It should be noted that IL-4, alone or in combination with IL-2 or IL-5, was not sufficient for inducing IgE class switching in these B cells, in contrast to the cells activated polyclonally with 20 micrograms/ml LPS, suggesting that an additional signal is required under the former conditions. After extensive screening of costimuli for inducing IgE in cooperation with IL-4, we found that 8-mercaptoguanosine (8-SGuo), a potent B cell activator, was effective. The addition of 8-SGuo to TNP-LPS-stimulated B cell cultures resulted in the secretion of both anti-TNP IgM and IgG1, but not anti-TNP IgE. Anti-TNP IgE formation was induced only when 8-SGuo was added in combination with IL-4, whereas 8-SGuo plus IL-4 failed to induce IgE secretion in the absence of TNP-LPS. Similar requirements for 8-SGuo and IL-4 for IgE formation were observed when B cells were stimulated with anti-mu. It was revealed that induction of the IgE responses was accompanied by increased frequency of surface IgE+ B cells and the expression of germline and productive epsilon transcripts. In B cells stimulated with anti-mu plus IL-4, 8-SGuo was shown to enhance the expression of the B cell-specific activator protein gene that is thought to be required in IL-4-dependent germline epsilon transcription.

Augmented humoral and anaphylactic responses in Fc gamma RII-deficient mice

Despite its widespread distribution on both lymphoid and myeloid cells, the biological role of the low-affinity immunoglobulin-G receptor, Fc gamma RII, is not fully understood. Defects in this receptor or its signalling pathway in B cells result in perturbations in immune-complex-mediated feedback inhibition of antibody production. We now report that Fc gamma RII-deficient animals display elevated immunoglobulin levels in response to both thymus-dependent and thymus-independent antigens. Additionally, the effector arm of the allergic response is perturbed in these mice. Mast cells from Fc gamma RII-/- are highly sensitive to IgG-triggered degranulation, in contrast to their wild-type counterparts. Fc gamma RII-deficient mice demonstrate an enhanced passive cutaneous analphylaxis reaction, the result of a decreased threshold for mast-cell activation by Fc gamma RIII cross-linking. These results demonstrate that Fc gamma RII acts as a general negative regulator of immune-complex-triggered activation in vivo for both the afferent and efferent limbs of the immune response. Exploiting this property offers new therapeutic opportunities for the treatment of allergic and autoimmune disorders.

Induction of antigen-specific IgE response in murine lymphocytes by IL-10

When murine spleen cells that had been primed with trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH) were stimulated in vitro with the same antigen, anti-TNP IgE, as well as anti-TNP IgM and IgG1, was secreted into the culture medium. On the other hand, anti-TNP IgM and IgG1 were produced, but anti-TNP IgE secretion was negligible when the carrier (KLH)-primed spleen cells were cultured with the hapten-carrier antigen (TNP-KLH) under the same conditions. Anti-TNP Ig responses in the latter cultures are thought to reflect the interaction between normal TNP-specific B cells and KLH-primed helper T cells. By using this culture system, we investigated the requirements of exogenous cytokines for inducing anti-TNP IgE response. The addition of interleukin-4 (IL-4), that is known to induce IgE response in LPS-stimulated murine B cells, failed to elicit anti-TNP IgE response. The combination of IL-4 with IL-2 and/or IL-5 was also ineffective. Interestingly, a significant level of anti-TNP IgE was induced when IL-10, another cytokine from type 2 helper T cells, was added to the culture. Although IL-10 enhanced the production of anti-TNP IgM and IgG1, as well as that of anti-TNP IgE, the rate of enhancement was at least 3-fold higher in the IgE response than in the IgM and IgG1 responses. Simultaneous addition of IL-4, IL-5 or IL-13 with IL-10 did not augment but rather reduced the enhancing effects of IL-10. IL-10 did not further stimulate the spontaneous secretion of IgE from antigen-primed B cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Phorbol ester-induced reversible inactivation of cytotoxic T cell function: correlation with down-regulation of protein kinase C activity

When an H-2d-specific cytotoxic T lymphocytes (CTL) clone, FC1, was incubated in the presence of 10(-7) M phorbol myristate acetate (PMA) for 10-12 hr, the cytolytic activity of the CTL against H-2d target cells was abrogated, but was reversibly restored to the normal level after subsequent incubation of the cells in PMA-free medium for more than 10 hr. These effects of PMA have been reported (Russell, J.H.: J. Immunol. 133, 907-912 (1984)), but the mode of its action has not been fully investigated. Here, we analyzed the biochemical basis of the PMA-induced loss of cytolytic activity. Cycloheximide completely blocked the restoration of the PMA-suppressed cytolytic activity, suggesting that protein synthesis was required in this process. PMA-treatment did not affect the levels of CD3 and CD8 molecules expressed on the CTL, nor was the level of a CTL-specific serine esterase, BLT esterase, affected by this treatment. However, the target cell-induced release of BLT esterase from the CTL was suppressed if the cells were pretreated with PMA. PMA-treatment of the CTL led to the down-regulation of protein kinase C (PKC) activity by about 50%. On the other hand, staurosporin, an inhibitor of PKC, completely blocked the target cell lysis when added at 10(-6) M. These results suggest that the down-regulation of at least some isoform(s) of PKC is responsible for the PMA-induced loss of the cytotolytic activity of CTL.

Effects of oxidized glutathione and reduced glutathione on the barrier function of the corneal endothelium

The protective effects of oxidized glutathione (GSSG) and reduced glutathione (GSH) in the irrigating solution based on BSS plus composition (Santen, Osaka, Japan), which is without GSSG (glutathione-free control solution) were compared on rabbit corneal endothelial barrier function. Corneal barrier function was evaluated by determining the effects of GSSG and GSH on carboxyfluorescein permeability (P(ac)). In a solution containing 0.3 mM GSSG (BSS plus), the P(ac) was significantly inferior to that of its paired glutathione-free control solution. With 0.6 mM GSH, the P(ac) was not different from that of its paired glutathione-free control solution. The P(ac) of the endothelium with 0.3 mM GSSG was significantly inferior to that of paired corneas exposed isolated to 0.6 mM GSH. These results show that the barrier function of the rabbit corneal endothelium is better maintained by supplementing the perfusion solution with 0.3 mM GSSG rather than 0.6 mM GSH.

Predominant suppression of anti-TNP IgE response in mice by monoclonal anti-TNP IgG1 antibody: characterization of its mode of action by in vitro and in vivo studies

It was found that an antigen-specific IgE response both in vitro and in vivo was strongly suppressed in the presence of IgG1 monoclonal antibody (mAb) against the antigen. Anti-trinitrophenyl (TNP) IgE response was elicited by the co-culture of C3H B-cells and a conalbumin (CA)-specific helper T-cell clone, D10.G4.1, in the presence of 0.1 microgram/ml TNP-CA. Addition of anti-TNP IgG1 monoclonal antibody (mAb) at 1 microgram/ml to the culture resulted in a marked (> 90%) suppression of anti-TNP IgE formation, while anti-TNP IgG1 and IgM responses were affected to a lesser extent (50-60% suppression). Similar observations were made in in vivo experiments. When 100-200 micrograms of anti-TNP IgG1 mAb was injected i.p. into BDF1 mice prior to immunization with TNP-CA, the anti-hapten (TNP) IgE response as well as the IgE response to the carrier (CA) was suppressed by 80-90%, while anti-TNP IgM production was inhibited by less than 50%. Injection of anti-TNP IgM or IgA mAb showed only marginal effects on anti-TNP IgE production. Spleen cells from anti-TNP IgG1 mAb-treated mice cultured in vitro secreted much lower levels of anti-TNP IgE spontaneously than those from untreated mice. In in vitro and in vivo experiments using the F(ab')2 of anti-TNP IgG1 mAb, an IgG1 mAb with an irrelevant specificity and mAb directed to Fc gamma RII, it was shown that the binding of the IgG1 mAb with the antigen and the interaction of its Fc portion with Fc gamma RII are required for the suppressive effects to be exerted.

Combined effects of hyaluronan and fibronectin on corneal epithelial wound closure of rabbit in vivo

We investigated the combined effects of hyaluronan and fibronectin on corneal epithelial wound closure in vivo. When fibronectin eye drops (1 mg/ml) were administered for the first 4 hours after chemical cautery and hyaluronan eye drops (1 mg/ml) were administered for following 32 hours, the mean healing rate was significantly higher than in control eyes treated with phosphate buffered saline instead of fibronectin or with initial fibronectin alone. These results demonstrated that hyaluronan and fibronectin have a synergistic effect, with fibronectin pretreatment augmenting hyaluronan-stimulated corneal epithelial wound closure.

Arachidonic acid stimulates corneal epithelial migration

We determined the concentration dependent effects of arachidonic acid between 0.3 and 30 x 10(-6) M on corneal epithelial migration, in an organ culture system of the rabbit cornea. With 3 x 10(-6) M arachidonic acid, corneal epithelial migration was maximally stimulated by 51%. The cyclooxygenase inhibitors, indomethacin, ketoprofen, flurbiprofen and diclofenac sodium also all had a tendency to stimulate corneal epithelial migration at low concentrations (0.1 or 1 x 10(-6) M). However, the inhibitory effect of epithelial migration was observed at higher concentration (100 x 10(-6) M) of these compounds. On the other hand, the selective 5-lipoxygenase inhibitor, AA-861 over a concentration range from 0.1 to 10 x 10(-6) M maximally inhibited corneal epithelial migration by 25%. These results suggest that during wound healing some of the increased release of arachidonic acid may be derived from a metabolite of the 5-lipoxygenase pathway which may in turn hasten wound closure.

Effect of ascorbic acid 2-O-alpha-glucoside on hydrocortisone-induced cataract formation in developing chick embryos: II. Influence on glutathione and lipid peroxide contents in the lens

In developing chick embryos, hydrocortisone induces cataract formation following a decrease in lens glutathione content but an increase in lipid peroxide content in lens, blood and liver. The preventive effects of ascorbic acid 2-O-alpha-glucoside (AA-2G) on these parameters were compared on cataract formation with those of ascorbic acid (AsA) and ascorbic acid 2-O-phosphate (AA-2P). In these tissues, AA-2G inhibited a decrease in glutathione content and an increase in lipid peroxide content more effectively than either AsA or AA-2P. Various tissues including lens and liver have alpha-glucosidase activity, strongly suggesting that AsA is enzymatically liberated from AA-2G in these tissues. In summary, these results suggest that AA-2G exerts a potent anti-cataract activity via a reduction in oxidative damage through AsA release.

A study on lipid peroxide-induced lens damage in vitro

The effects of linolenic acid hydroperoxide (LAPO) on isolated rat lenses were investigated, because they are believed to be cataractogenic in vivo. They were also compared with the effect of linolenic acid (LA), source of LAPO. Rat lenses, which were exposed for 5 hr to either 210 microM or 420 microM LAPO, became cloudy and this change was associated with increases in the level of malondialdehyde (MDA), a breakdown product of lipid peroxide, and decreases in non-protein thiol (NP-SH) content. Concomitantly, there were changes in cation contents: Na+ and Ca2+ were increased whereas K+ and Mg2+ were decreased. The changes in the levels of the above parameters, correlated with the concentration and the treatment time of LAPO to which the lenses were exposed. The increase of MDA was 2-4-fold over normal level and was consistent with those in cataractous lenses of the human and experimental animal models. On the other hand, if the lenses were exposed to LA, the only change observed was a small alteration of cationic content. If the lenses were cultured for an additional 24 hr in the absence of either LA or LAPO, the cation content continued to change only in those lenses which were previously exposed to LAPO. These results show that at concentrations of lipid peroxides, which are associated with the development of cataract in the human and animal models, there are changes in vitro in cation content, MDA and NP-SH levels, which accompany the development of a lens opacity.

The secondary antigen-specific IgE response in murine lymphocytes is resistant to blockade by anti-IL4 antibody and an antisense oligodeoxynucleotide for IL4 mRNA

In order to investigate the role of interleukin 4 (IL4) in the induction of antigen-specific IgE responses, we established culture conditions which allow the induction of anti-trinitrophenyl(TNP) IgE response by the coculture of TNP-keyhole limpet hemocyanin-primed C3H B cells with conalbumin (CA)-specific type 2 helper T (Th2) cell clone, D10.G4.1 in the presence of TNP-CA. A maximum level of anti-TNP IgE was secreted at 1 microgram/ml TNP-CA. By using filter-separated double-chamber culture plates, the physical contact between T cells and B cells was shown to be necessary in this response. Anti-TNP IgE synthesis was not significantly suppressed in the presence of 20-40 micrograms/ml monoclonal anti-IL4 (11B11), nor was the response further enhanced by the addition of recombinant IL4. 11B11 added together with anti-IL5 had also no suppressive effects on the IgE response. This apparent independence on IL4 might be due to the fact that IL4 is transferred from T cells to B cells in a transsynaptical way that would be refractory to the neutralization by 11B11. In order to test this possibility, we synthesized the phosphorothioate analogue of an antisense oligodeoxynucleotide against IL4 mRNA (S-oligo) for inhibiting IL4 production from Th2 cells specifically. S-oligo was effective at 10-20 micrograms/ml in suppressing IL4 production from D10.G4.1 cells by 80-90%. It was demonstrated that S-oligo, either alone or in combination with 11B11, did not significantly suppress anti-TNP IgE response. These results suggest that antigen-specific IgE response in primed B cells does not depend on IL4, but requires cognate interaction with Th2 cells.

Possible usefulness of cephem antibiotics with anti-staphylococcal activity for preventing the spread of methicillin-resistant Staphylococcus aureus

The validity of clinical use of cephem antibiotics for preventing the spread of methicillin-resistant Staphylococcus aureus (MRSA) was investigated using a methicillin-susceptible S. aureus (MSSA) carrying mecA gene. It became evident that drug with anti-staphylococcal activity, such as cefuzonam (CZON) or cefazolin (CEZ), has comparatively low selectivity of high-level methicillin resistant clones (methicillin MIC range from 25 to 800 micrograms/ml) from MSSA carrying mecA gene among cephem antibiotics tested. At concentrations over 1.56 micrograms/ml of both CZON and CEZ, about a 2-3 log10 decrease in viable count was observed. Therefore, it seems that much satisfactory disappearance of bacterial cells can be obtained in cooperation with host defence mechanisms.

Characterization of water retentive properties of hyaluronan

We examined the water retentive properties of hyaluronan because of its reported therapeutic effect in the treatment of dry eye. Hyaluronan dose dependently retarded water loss from a solution kept at constant temperature and humidity. Similarly, water loss was retarded when hyaluronan was placed atop an agar gel. These decreases in water loss were not related to changes in the molecular weight of hyaluronan. Unlike the in vitro models, the evaporation rate from the tears in normal subjects initially increased following the topical application of hyaluronan, and continued a higher rate than with the vehicle. These results suggest that hyaluronan enhances water retention on the corneal surface, and probably increases corneal wettability. Accordingly, hyaluronan eye drops may be useful in the treatment of dry eye.

Enzyme release assay of human NK cell activity using beta-galactosidase-expressing K562 target cell line

In the present report, we established a K562 cell line useful for an enzyme release assay of human natural killer (NK) activity. Human myelogenous leukemia cell line, K562, was transfected with a plasmid carrying Escherichia coli beta-galactosidase (beta-gal) gene. A colony that permanently expresses the enzyme activity was isolated, and designated K562/Zneo. Incubation of K562/Zneo cells (1 x 10(4)) with nonadherent human peripheral blood lymphocytes (PBL) resulted in the release of beta-gal activity depending on the incubation time and the number of effector cells. Released beta-gal activity was assayed sensitively by using 4-methylumbelliferyl-beta-D-galactoside, a fluorescent substrate. The cytolytic activity of PBL was augmented significantly when the cells were preincubated with interleukin-2 for 20 h. This enzyme release assay showed a comparable sensitivity to that of 51Cr release assay. Thus, K562/Zneo cell line is thought to be useful for the nonradioactive assay of human NK and lymphokine-activated killer activities.

Suppression of IgE antibody response in mice by a naphthalene derivative, TEI-6472

In the present report, we investigated suppressive effects of a naphthalene derivative, (7E)-N-(2-carboxyphenyl)-8-(2-naphthyl)-5,6-trans-5,6-methano-7- octenamide L-lysine salt (TEI-6472), on in vitro and in vivo antigen-specific IgE response. Anti-trinitrophenyl (TNP) IgE response induced in vitro in TNP-keyhole limpet hemocyanin (KLH)-primed murine spleen cells was suppressed by about 60% in the presence of 10(-6) M TEI-6472. On the other hand, anti-TNP IgG1 and IgM response were not significantly suppressed under the same conditions. Proliferative responses of BALB/c spleen cells stimulated by lipopolysaccharide, concanavalin A or allogeneic spleen cells were not inhibited by TEI-6472 at 10(-6)-10(-5) M. Interleukin 4 production from helper T-cell clone, D10.G4.1 was suppressed only slightly (less than 20%) at 10(-6) M TEI-6472. This compound was also effective in suppressing secondary anti-TNP IgE response in mice that were immunized twice with TNP-KLH and alum. When 10-20 mg/kg/day TEI-6472 was administered s.c. for 5 consecutive days starting from one day before the first and the second immunization, secondary anti-TNP IgE response was inhibited most strongly (40-45%). Anti-TNP IgG1 response was also inhibited but to a smaller extent (20-24%), while anti-TNP IgM response was suppressed only slightly (0-15%). These results suggest that, under appropriate conditions, TEI-6472 can suppress IgE responses more preferentially both in vitro and in vivo.

Low neurotoxicity of LJC 10,627, a novel 1 beta-methyl carbapenem antibiotic: inhibition of gamma-aminobutyric acidA, benzodiazepine, and glycine receptor binding in relation to lack of central nervous system toxicity in rats

The toxicity of LJC 10,627 to the central nervous system of rats was evaluated by examining the effects of the compound on gamma-aminobutyric acidA, benzodiazepine, and glycine receptor binding in rat synaptic membranes and on the induction of behavioral convulsions by intraventricular administration to rats. The concentrations of this compound needed to inhibit specific [3H]muscimol binding, specific [3H]diazepam binding, and specific [3H]strychnine binding were greater than those of imipenem, as demonstrated by the 50% inhibitory concentrations (IC50S of LJC 10,627, greater than 10 mM for each; IC50S of imipenem, 0.6, 1.9, and 0.2 mM, respectively). These results reflect the fact that LJC 10,627 does not evoke severe convulsions or cause death, even when it is administered intraventricularly at a high dose (300 micrograms per rat), and suggest that the low neurotoxic potential of LJC 10,627 may be attributed to the chemical structure of this compound, which has a methyl radical at the 1 beta site and a triazolium radical at the side chain of the second site.

Characterization of esterases involved in the hydrolysis of dipivefrin hydrochloride

We characterized the interaction of the prodrug dipivefrin hydrochloride (DPE) with esterase activity in the rabbit cornea. The esterases which were identified included: (1) cholinesterase, (2) acetylcholinesterase, (3) a mixture containing carboxylesterase, acetylesterase and arylesterase, and (4) a non-specific esterase. DPE suppressed all of their activities as well as that of the mixture containing carboxylesterase, acetylesterase and arylesterase, and a nonspecific esterase. However, its effect on cholinesterase was larger than on any of the other activities, suggesting that DPE is a better substrate for cholinesterase than for any of the other esterases. These measurements along with those of substrate-dependent inhibition of 14C-DPE hydrolysis indicated that the DPE-esterase interaction was competitive based on changes in the apparent Km values which were extracted from Lineweaver-Burk plots of esterase activity. The substrate for cholinesterase competed with DPE most strongly among substrates. These results seem to suggest that DPE is hydrolyzed by various corneal esterases, mainly cholinesterase.

Effect of ascorbic acid 2-0-alpha-glucoside on hydrocortisone-induced cataract formation in developing chick embryos: I. Comparison of the preventive effect of ascorbic acid derivatives

The effect of ascorbic acid 2-O-alpha-glucoside (AA-2G) on hydrocortisone (HC)-induced lens opacity in developing chick embryo was examined and compared with those of ascorbic acid (AsA) and ascorbic acid 2-phosphate (AA-2P). The opacity was dose-dependently inhibited by a single administration of 10 or 20 mumol/egg of AA-2G and by three repeated administrations of 1, 3 or 10 mumol/egg of AA-2G. AA-2G was the most effective among the three compounds. Glucose did not enhance the preventive effect of AsA against HC-induced opacity, and neither dehydro ascorbic acid nor glucose also prevented HC-induced cataract. In the histological study, we observed many small vacuoles in the nuclear region of the opaque lens treated with HC. AA-2G inhibited the formation of such vacuoles, an effect closely correlated with the prevention of cataract formation.

Comparative stability of carbapenem and penem antibiotics to renal dehydropeptidase-I

Comparison has been made on the stability of 4 carbapenems and 3 penems against porcine renal dehydropeptidase-I (DHP-I). Evaluated were the carbapenems (5R,6S)-3-[[2-(formimidoylamino)ethyl]thio]-6-[(R)-1-hydroxyethyl] - 7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid monohydrate, CAS 74431-23-5, in the following called FAC, (5R,6S)-3-[(S)-1-(acetimidoylpyrrolidin-3-yl)thio]-6-[(R)-1- hydroxyethyl]-7-oxo-1-azabicyclo[3.2.0] hept-2-ene-2-carboxylic acid, CAS 87726-17-8, in the following called AHC, (4R,5S,6S)-3-[[(3S,5S)-5-dimethylcarbamoylpyrrolidin-3-yl]thio]-6- [(1R)-1-hydroxyethyl]-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2- carboxylic acid trihydrate, CAS 96036-03-2, in the following called DHC. (1R,5S,6S)-2-[(6,7-dihydro-5H-pyrazolo[1,2-a] [1,2,4]triazolium-6-yl)thio]-6-[(R)-1-hydroxyethyl]-1-methyl-ca rbapen - 2-em-3-carboxylate, in the following called DHM, and the penems (5R,6S)-6-[(R)-1-hydroxyethyl]-7-oxo-3-[(R)-2-tetrahydrofuryl]-4-thia-1 - azabicyclo [3.2.0]hept-2-ene-2-carboxylic acid sodium salt, in the following called HTC, (5R,6S)-2-carbamoyloxymethyl-6-[(1R)-hydroxyethyl]-2-penem-3-carboxylic acid, in the following called CHC, (5R,6S)-6-[(R)-1-hydroxyethyl]-3-[(3S)-(cis-1-oxotetrahydrothiophen++ +-3-yl) thio]-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, in the following called HHC. According to the comparison of the Vmax/Km ratios, the order of stability of the compounds to hydrolysis by renal DHP-I was as follows: DHM >> DHC > HHC > AHC > HTC > CHC > FAC. From this result it is particularly noteworthy that DHM has extremely high stability against renal DHP-I.

Removal of lens epithelial cells following loosening of the junctional complex

We previously reported a new method to remove residual lens epithelial cells--dispersion aspiration. The cells were loosened from their junctional complexes with Dispase, a proteolytic enzyme. To avoid intraocular tissue damage, the enzyme preparation was dissolved in sodium hyaluronate and injected into the capsular bag, which was carefully preserved during endocapsular cataract surgery. The cells were then removed by minimum irrigation/aspiration. In this study we incorporated ethylenediaminetetraacetic acid (EDTA), a calcium chelating agent for separating epithelial cells in tissue culture, into the procedure. The results of experiments in vitro and in rabbits suggest that this procedure also removed cells effectively with negligible damage to the zonules and corneal endothelium.

Antigen-specific but not polyclonal IgE response in murine B cells cocultured with Th2 clone is refractory to suppression by IL4-depletion

We established culture conditions allowing the induction of antitrinitrophenyl (TNP) IgE response by the coculture of unprimed C3H B cells with conalbumin (CA)-specific type 2 helper T cell clone, D10.G4.1 in the presence of TNP-CA. With the help of this culture system, the role of Th2 cells and interleukin 4 (IL4) derived from them in the induction of antigen-specific IgE response was analyzed. A maximum level of anti-TNP IgE was secreted at 0.5-1 micrograms/ml TNP-CA. When the antigen was increased to 100 micrograms/ml, anti-TNP IgE production was abolished, while antigen-nonspecific (polyclonal) IgE was produced concomitantly. Anti-TNP IgE synthesis was not significantly suppressed in the presence of monoclonal anti-IL4 (11B11), nor was the response further enhanced by the addition of recombinant IL4. In contrast, polyclonal IgE response was abolished by 11B11. In order to deplete endogenous IL4 more strictly, we employed an antisense DNA for IL4 mRNA that can effectively inhibit IL4 production from D10 cells. Even in the presence of both 11B11 and the antisense DNA, it was found that anti-TNP IgE response was not suppressed significantly. These results suggest that antigen-specific IgE response induced in B cells cocultured with established Th2 cells does not depend on IL4 in contrast to polyclonal IgE response.

Suppression of interleukin 4 production from type 2 helper T cell clone by antisense oligodeoxynucleotide

Type 2 helper T cell (Th2) clone has been reported to secrete interleukin (IL) 4 and IL5 in response to the specific antigen presented by syngeneic antigen-presenting cells. In the present report, we synthesized phosphorothioate analogue of an antisense oligodeoxynucleotide complementary to nucleotide 17-36 of IL4 mRNA (S-oligo), and tested its ability to inhibit IL4 production from a Th2 clone, D10.G4.1. (D10). D10 cells were cultured with mitomycin C-treated C3H spleen cells in the presence of 100 micrograms/ml conalbumin for 48-72 h. Secreted IL4 and IL5 were assayed biologically using HT2 cells and dextran sulfate-stimulated murine B cells, respectively. When 5-10 micrograms/ml S-oligo was added to the culture, IL4 production from D10 was suppressed by 70-90%. The same concentrations of S-oligo inhibited neither the antigen-induced proliferation of D10 nor the secretion of IL5 from the Th2 clone. These results suggest that this S-oligo is useful for inhibiting the production of IL4 preferentially without affecting other functions of Th2 cells.

Enhancement of antigen-induced interleukin 4 and IgE production by specific IgG1 in murine lymphocytes

Conalbumin (CA)-specific type 2 helper T cell (Th2) clone, D10G4.1 (D10) produces IL4 when stimulated with varying doses of TNP-CA in the presence of mitomycin C-treated C3H spleen cells or purified B cells as antigen-presenting cells (APC). The production of IL4 was assessed by bioassay and by expression of IL4 mRNA. IL4 production reached maximum at 100 micrograms/ml of TNP-CA, whereas 1 microgram/ml of the antigen induced less than 10% of the maximum level of IL4. This lower level of IL4 production was augmented to the maximum level when monoclonal anti-TNP IgG1 was added to the culture at 0.5-1 microgram/ml. Anti-TNP IgE, but not anti-TNP IgM, was also effective, though IgE was 1/10 as effective as IgG1. IgG1 with an irrelevant specificity and F(ab')2 of anti-TNP IgG1 did not show augmenting effects. Moreover, the enhancement by anti-TNP IgG1 was completely abolished by monoclonal antibody against murine Fc gamma RII, 2.4G2. These results suggest that a low dose of the antigen complexed with IgG1 is focused on APC by means of Fc gamma RII, processed, and presented efficiently to the Th2 clone. On the other hand, the co-culture of D10 with normal C3H B cells in the presence of 1-100 micrograms/ml TNP-CA resulted in polyclonal IgE production. Anti-TNP IgG1 markedly augmented the lower level of IgE production induced by a suboptimal dose of the antigen (1 microgram/ml). This augmentation was shown to be dependent on endogenous IL4 because the enhancement was abolished by monoclonal anti-IL4 (11B11).

Concentration and molecular weight dependency of rabbit corneal epithelial wound healing on hyaluronan

Hyaluronan (hyaluronic acid) is a high molecular weight viscoelastic polymer which has been postulated to enhance wound healing. We investigated the dose and molecular weight (9 x 10(4)-280 x 10(4) dependent effects of hyaluronan on the rate of migration of rabbit corneal epithelium in organ culture and on wound closure in vivo after debridement with n-heptanol. When corneal blocks were cultured with hyaluronan for 20 hours, distances of epithelial migration significantly increased over exposed stroma in proportion to hyaluronan concentration. However, there was no difference in the stimulatory action of hyaluronan on epithelial migration when corneal blocks were cultured at 1 mg/ml of hyaluronan irrespective of changes in the molecular weight range between 9 x 10(4) and 280 x 10(4). Glycosaminoglycans other than hyaluronan (chondroitin, chondroitin sulfate, keratan sulfate and heparan sulfate) failed to increase the epithelial migration. When hyaluronan eye drops were instilled after corneal epithelial removal with n-heptanol, hyaluronan stimulated wound closure in a dose-dependent manner, but its stimulatory efficacy was not dependent on molecular weight.

In vitro antigen-specific IgE response is refractory to suppression by interferon-gamma

Although interferon (IFN)-gamma has been shown to be involved in the down-regulation of polyclonal IgE response in murine B cells that were activated by lipopolysaccharide (LPS) and interleukin 4 (IL4), effects of IFN-gamma on antigen-specific IgE responses have not been fully investigated. We have developed the following culture systems for inducing antigen-specific IgE responses in murine lymphocytes, and examined the effects of IFN-gamma on the following responses in vitro. (1) Anti-trinitrophenyl (TNP) IgE response induced by the stimulation with TNP-keyhole limpet hemocyanin (KLH) of BALB/c spleen cells that had been primed in vivo with the same antigen. (2) Anti-TNP IgE response induced by the coculture of unprimed C3H B cells with conalbumin (CA)-specific helper T cell clone, D10.G4.1, in the presence of TNP-CA. The former anti-TNP IgE response was not suppressed, and the latter suppressed only partially (less than 30%) by the addition of 100-200 U/ml IFN-gamma. In contrast, polyclonal IgE response in murine B cells that were stimulated by LPS and IL4 was abolished by 10 U/ml IFN-gamma. These results indicate that IgE production from antigen-stimulated B cells, in contrast to those activated polyclonally, are refractory to direct suppression by IFN-gamma.

Interleukin 6 facilitates corneal epithelial wound closure in vivo

Rapid corneal epithelial wound healing is essential to the maintenance of clear visual acuity. The cytokine interleukin 6 is thought to participate in the wound-healing process. We investigated the effect of interleukin 6 eye drops on the rate of corneal epithelial wound closure in rabbits in vivo. Recombinant human interleukin 6 in phosphate-buffered saline at concentrations of 0.1, 0.3, or 1 mg/L was administered immediately after the epithelium was débrided with the n-heptyl alcohol treatment and 2, 4, 6, 8, 10, 18, 20, 22, 24, 26, and 28 hours after débridement. The eyes were stained with fluorescein and photographed at baseline and at 7, 10, 18, 21, 24, 27, 30, and 43 hours after débridement. The rate of wound healing was calculated with a linear regression analysis based on the areas of the epithelial defects, which were recorded from hour 10 to hour 30. The mean (+/- SD) healing rate in the control group, which received phosphate-buffered saline alone, was 1.03 +/- 0.15 mm2/h. The administration of interleukin 6 at concentrations of 0.1, 0.3, or 1.0 mg/L increased the healing rate significantly (P less than .001) to 1.27, 1.39, or 1.44 mm2/h, respectively. Our results indicate that the administration of interleukin 6 might have clinical applications in the treatment of persistent corneal epithelial defects.