Prostaglandin E2 as a selective stimulator of antigen-specific IgE response in murine lymphocytes

APRIL and BAFF promote increased viability of replicating human B2 cells via mechanism involving cyclooxygenase 2

Of relevance to both protective and pathogenic responses to Ag is the recent finding that soluble molecules of the innate immune system, i.e., IL-4, B cell-activation factor of the TNF family (BAFF), and C3, exhibit significant synergy in promoting the clonal expansion of human B2 cells following low-level BCR ligation. Although IL-4, BAFF, and C3dg each contribute to early cell cycle entry and progression to S phase, only BAFF promotes later sustained viability of progeny needed for continued cycling. The present study sought to further clarify the mechanisms for BAFF's multiple functions. By comparing BAFF and a proliferation-inducing ligand (APRIL) efficacy at different stages in the response (only BAFF binds BR3; both bind transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B cell maturation Ag, the early role was attributed to BR3, while the later role was attributed to TACI/B cell maturation Ag. Importantly, BAFF- and APRIL-promoted viability of cycling lymphoblasts was associated with sustained expression of cyclooxygenase 2 (COX-2), the rate-limiting enzyme for PGE2 synthesis, within replicating cells. Supernatants of cultures with BAFF and APRIL contained elevated PGE2. Although COX-2 inhibitors diminished daughter cell viability, exogenous PGE2 (1-1000 nM) increased the viability and recovery of lymphoblasts. Increased yield of viable progeny was associated with elevated Mcl-1, suggesting that a BAFF/APRIL --> TACI --> COX-2 --> PGE2--> Mcl-1 pathway reduces activation-related, mitochondrial apoptosis in replicating human B2 cell clones.

Antipruritic effect of ginsenoside rb1 and compound k in scratching behavior mouse models

The antipruritic and vascular permeability-inhibitory effects of ginsenoside Rb1, a main component of ginseng frequently used as a traditional medicine in Asian countries, and its metabolite compound K by intestinal microflora were investigated in scratching behavior animal models induced by compound 48/80, substance P, and histamine. Ginsenoside Rb1 and compound K orally administered 1 and 6 h before the treatment of compound 48/80 showed antipruritic effect. These ginsenosides administered at a dose of 50 mg/kg 6 h before the treatment of compound 48/80 inhibited scratching behaviors by 51% and 64%, respectively, compared with that of the control. These ginsenosides also inhibited the vascular permeability of skin. Compound K intraperitoneally administered 1 h before the treatment of compound 48/80 potently inhibited the scratching behaviors induced by compound 48/80. However, intraperitoneally administered ginsenoside Rb1 did not inhibit scratching behaviors. Compound K inhibited compound 48/80-, substance P-, and histamine-induced scratching behaviors, with 50% inhibitory doses of 4.2, 5.9, and 3.8 mg/kg, respectively, and vascular permeability, with 50% inhibitory doses of 5.8, 6.8, and 4.1 mg/kg, respectively. These results suggest that ginsenoside Rb1 and its metabolite compound K by intestinal microflora can improve scratching behaviors.

Inhibitory effect of ginsenoside Rb1 and compound K on NO and prostaglandin E2 biosyntheses of RAW264.7 cells induced by lipopolysaccharide

In this study, the antiinflammatory activities of ginsenoside Rb1, which is a main constituent of the root of Panax ginseng (Araliaceae), and of its metabolite compound K, as produced by human intestinal bacteria, on lipopolysaccharide (LPS)-induced RAW264.7 cells were investigated. Compound K potently inhibited the production of NO and prostaglandin E2 in LPS-induced RAW 264.7 cells, with IC(50) values of 0.012 and 0.004 mM, respectively. Compound K also reduced the expression levels of the inducible NO synthase (iNOS) and COX-2 proteins and inhibited the activation of NF-kB, a nuclear transcription factor. Compound K inhibited the NO level produced by iNOS enzyme activity in a cell-free system, but did not inhibit COX-1 and 2 activities. When ginsenoside Rb1 was orally administered to rats, compound K, but not ginsenoside Rb1, were excreted in their urine. These findings suggest that ginsenoside Rb1 can be transformed to compound K by intestinal bacteria, and compound K may be effective against inflammation.

Analysis of marginal zone B cell development in the mouse with limited B cell diversity: role of the antigen receptor signals in the recruitment of B cells to the marginal zone

The quasimonoclonal (QM) mouse provides an intelligible model to analyze the B cell selection as the competition between two major 4-hydroxy-3-nitrophenylacetyl-specific B cell populations whose BCR are comprised of the knockin V(H)17.2.25 (V(H)T)-encoded H chain and the lambda1 or lambda2 L chain. In this study, we show the QM system is useful to examine how BCR signals guide a subset of B cells to the marginal zone (MZ). Compared with the control C57BL/6 mice, the QM mice had approximately 2.7-fold increased number of B cells exhibiting the MZ B cell phenotype and a larger MZ area in the spleen. Interestingly, V(H)T/lambda2 B cells significantly predominated over V(H)T/lambda1 B cells in MZ-(V(H)T/lambda1:V(H)T/lambda2 approximately 3:7) and transitional 2-B cell subsets, while these two populations were comparable in immature, transitional 1, and mature counterparts. Thus, the biased use of lambda2 in the MZ B cells may be the result of selection in the periphery. The enlargement of MZ B cell compartment and the preferred recruitment of the V(H)T/lambda2 B cells were further augmented by doubling the V(H)T gene, but dampened by the dysfunction of Bruton's tyrosine kinase, suggesting a positive role of BCR signaling in this selection. Comparison of Ag specificity between V(H)T/lambda1 and V(H)T/lambda2 IgM mAbs revealed a polyreactive nature of the V(H)T/lambda2 BCR, including the reactivity with ssDNA. Taken together, it is suggested that polyreactivity (including self-reactivity) of BCR is crucial in driving B cells to differentiate into the MZ phenotype.

Cholesterol selectively enhances in vitro latex-specific IgE production in atopic dermatitis patients with latex allergy

Effect of cholesterol on in vitro latex-specific IgE production by mononuclear cells from atopic dermatitis patients with latex allergy. Cholesterol enhanced latex-specific IgE production in a dose-dependent fashion, and maximal enhancement was achieved at 1 microg/ml. In contrast, cholesterol had no effect on latex -specific IgA or IgG4 production. Study for cytokine production revealed that cholesterol decreased latex-induced production of IFN-gamma and IL-12, while it increased latex-induced production of IL-4, IL-10 and IL-13. These results indicate that cholesterol skews cytokine pattern toward Th2 type. Collectively, cholesterol may increase allergen-specific IgE production, which may in turn aggravate allergic symptoms.

Passive Cutaneous Anaphylaxis-Inhibitory Action of Tectorigenin, a Metabolite of Tectoridin by Intestinal Microflora

Tectoridin isolated from the flowers of Pueraria thunbergiana (Leguminosae) are metabolized to tectorigenin by human intestinal microflora. When tectoridin was orally administered to rats, tectorigenin, but not tectoridin, was detected in urine after beta-glucuronidase hydrolysis. The main metabolite tectorigenin potently inhibited the passive cutaneous anaphylaxis reaction and inhibited in vitro the release of beta-hexosaminidase from RBL-2H3 cells induced by IgE. These results suggest that tectoridin is a prodrug, which can be transformed into the active agent tectorigenin by human intestinal bacteria and can be a candidate for antiallergic agent.

B cell selection and affinity maturation during an antibody response in the mouse with limited B cell diversity

The quasi-monoclonal mouse has limited B cell diversity, whose major (approximately 80%) B cell Ag receptors are comprised of the knockin V(H) 17.2.25 (V(H)T)-encoded H chain and the lambda1 or lambda2 L chain, thereby being specific for 4-hydroxy-3-nitrophenylacetyl. The p-nitrophenylacetyl (pNP) was found to be a low affinity analog of nitrophenylacetyl. We examined affinity maturation of anti-pNP IgG by analyzing mAbs obtained from quasi-monoclonal mice that were immunized with this low affinity Ag. The results are: 1) Although V(H)T/lambda1 and V(H)T/lambda2 IgM were equally produced, V(H)T/lambda2 IgG almost exclusively underwent affinity maturation toward pNP. 2) A common mutation in complementarity-determining region 3 of V(H)T (T313A) mainly contributed to generating the specificity for pNP. 3) Because mutated V(H)T-encoded gamma-chains could form lambda1-bearing IgG in Chinese hamster ovary cells, apparent absence of V(H)T/lambda1 anti-pNP IgG may not be due to the incompatibility between the gamma-chains and the lambda1-chain, but may be explained by the fact that V(H)T/lambda1 B cells showed 50- to 100-fold lower affinity for pNP than V(H)T/lambda2 B cells. 4) Interestingly, a pNP-specific IgM mAb that shared common mutations including T313A with high affinity anti-pNP IgG was isolated, suggesting that a part of hypermutation coupled with positive selection can occur before isotype switching. Thus, even weak B cell receptor engagement can elicit an IgM response, whereas only B cells that received signals stronger than a threshold may be committed to an affinity maturation process.

Prostaglandin E2 and cAMP promote B lymphocyte class switching to IgG1

Prostaglandins of the E series (PGE) have traditionally been considered as suppressive for immune responses; however, recent data suggest that PGE channels the immune response towards a T helper 2 type response and production of selected immunoglobulin isotypes. Herein, we present data showing that PGE(2) and other agents that induce intracellular rises in cAMP significantly increased B lymphocyte IgG1 production (up to sevenfold). PGE(2) acted on small resting B cells and on uncommitted B cells expressing high levels of surface IgM to increase the number of cells secreting IgG1. PGE(2) even increased IgG1 synthesis by purified B cells in the absence of exogenous IL-4. Finally, PGE(2) synergized with IL-4 to induce germline gamma1 transcripts through the switch region. This transcription is required for isotype switching. These data support the hypothesis that PGE(2) acts on uncommitted resting B cells at the level of germline gamma1 transcription to promote class switching to IgG1. PGE(2) is an important regulator of the immune response, shifting the balance towards a T helper type 2 response, directing selection of the isotypes produced, and promoting memory cell formation.

Suppression of IgE antibody response in mice by a polysaccharide, AZ9, produced by Klebsiella oxytoca strain TNM3

A soil bacterium, Klebsiella oxytoca TNM3 was found to produce a polysaccharide named AZ9 that shows suppressive effects on IgE antibody response in mice. When mice were administered with 50 to approximately 100 mg/kg AZ9 subcutaneousely for 4 consecutive days after immunization with trinitrophenyl (TNP)-keyhole limpet hemocyanin, anti-TNP IgE production was significantly suppressed, while the level of anti-TNP IgM was affected marginally. In AZ9-administered mice, IL-4 secretion from splenic cells was reduced to approximately 30% of the untreated control. Thus, AZ9 suppression of IgE production may be due to attenuating effects on the Th2-type response. Although oral administration of AZ9 alone had no effects on IgE production, ovalbumin (OVA)-induced oral tolerance of anti-TNP IgE response to TNP-OVA was markedly augmented when a suboptimal dose of OVA was administered orally in combination with AZ9. Collectively, our data suggest that AZ9 has beneficial suppressive effects on IgE-dependent allergic responses.

Inhibitory effect on immunoglobulin E production in vivo and in vitro by Siegesbeckia glabrescens

Elevated levels of immunoglobulin (Ig)E are associated with immediate-type allergic reactions. The effect of an aqueous extract of Siegesbeckia glabrescens (Compositae) whole plants (SGWP) on in vivo and in vitro IgE production was studied in mice. SGWP dose-dependently inhibited the active systemic anaphylaxis and serum IgE production induced by immunization with ovalbumin and Bordetella pertussis toxin absorbed to aluminium hydroxide gel. SGWP dose-dependently inhibited IL-4-dependent IgE production by lipopolysaccharide-stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, SGWP also showed an inhibitory effect on IgE production. These results suggest that SGWP has an anti-allergic activity by inhibiting IgE production from B cells.

Suppression of allergic reactions by royal jelly in association with the restoration of macrophage function and the improvement of Th1/Th2 cell responses

We studied the immunomodulatory effects of royal jelly (RJ), the principal food source of the queen honeybee. In this study, suppression of allergic reactions by RJ was investigated in DNP-KLH immunized mice (DNP-KLH mice). Oral administration of RJ (1 g/kg) to DNP-KLH mice significantly decreased the serum levels of antigen-specific Ig E and significantly inhibited DNP-KLH mediated-histamine release from mast cells, resulting in the suppression of immediate hypersensitivity reactions of ear skin. In DNP-KLH mice, IFN-gamma (Th1 cytokine) production from CD4+ T cells was suppressed and IL-4 (Th2 cytokine) production from CD4+ T cells was increased as compared to normal mice. On the other hand, RJ improved the balance of Th1/Th2 cell responses from Th2-dominant to Th1-dominant. RJ significantly increased GSH levels in macrophages from DNP-KLH mice. In addition, the administration of RJ to DNP-KLH mice increased IL-12 p40 mRNA expression and NO production, and decreased PG E2 production from macrophages as compared to untreated DNP-KLH mice. These results suggested that RJ suppressed antigen-specific Ig E production and histamine release from mast cells in association with the restoration of macrophage function and improvement of Th1/Th2 cell responses in DNP-KLH mice.

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.

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.

Inhibition of immunoglobulin E production by Poncirus trifoliata fruit extract

Immunoglobulin E (IgE) is the principal immunoglobulin involved in immediate hypersensitivities and chronic allergic diseases. The effect of an aqueous extract of Poncirus trifoliata (L) Raf. (Rutaceae) fruits (PTFE) on in vivo and in vitro IgE production was investigated. PTFE dose-dependently inhibited the active systemic anaphylaxis and serum IgE production induced by immunization with ovalbumin, Bordetella pertussis toxin and aluminum hydroxide gel. PTFE strongly inhibited interleukin 4 (IL-4)-dependent IgE production by lipopolysaccharide-stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, PTFE also showed an inhibitory effect on the IgE production. These results suggest that PTFE has an anti-allergic activity by inhibition of IgE production from B cells.

Asiasari radix inhibits immunoglobulin E production on experimental models in vitro and in vivo

Immunoglobulin (Ig) E is the principal Ig involved in immediate hypersensitivities and chronic allergic diseases. The hallmark of these disorders is increased IgE production. The effect of an aqueous extract of the roots of Asiasari radix (ARAE) on an in vivo and in vitro IgE production was investigated. ARAE dose-dependently inhibited the active systemic anaphylaxis and serum IgE production induced by immunization with ovalbumin, Bordetella pertussis toxin and aluminum hydroxide gel. ARAE strongly inhibited IL-4-dependent IgE production by lipopolysaccharide- stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, ARAE also showed an inhibitory effect on the IgE production. These results suggest that ARAE has an anti-allergic activity by inhibition of IgE production from B cells.

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.

Novel naphthalene derivatives as inhibitors of human immunoglobulin E antibody production

A series of naphthalene derivatives with a variety of substituents at the 2-position was prepared in order to evaluate their suppressive effect on immunoglobulin E (IgE) antibody production by human peripheral blood mononuclear cells provoked with anti-CD40 antibody (alpha-CD40), interleukin-4 (IL-4), and interleukin-10 (IL-10). Compounds having a 1,4-phenylene spacer moiety tethered between the 2-naphthyl nucleus and anthranilic acid suppressed IgE antibody production in vitro in preference to that of IgG antibody without affecting cell viability. Deletion of the anthranilic acid moiety diminished the inhibitory activities. Changing the 2-naphthyl to a 1-naphthyl or phenyl nucleus led to no change in the potency, indicating that the aromatic group at this position is indispensable for the inhibitory activities. On the other hand, changing the 1,4-phenylene spacer to a 1,3-phenylene one resulted in reduced potency. Similarly, inhibitory activities were lost when the CO2H moiety at the 2-position was moved to the 3- or 4-position on the terminal benzene. These observations suggest that the conformation around the anthranilic acid moiety affects the inhibitory activities toward IgE biosynthesis. 2-(4-(2-Naphthyloxy)benzamido)benzoic acid (29) seemed to be a more potent inhibitor of IgE production than of IgG production. Insertion of a methylene between the inter-phenylene and the amide moiety resulted in 2-((4-(2-naphthyloxy)phenyl)acetamido)benzoic acid (31), which provided a stronger inhibition of both IgE and IgG production, although the selectivity toward IgE was lower than that of 29. Introduction of a benzyl group at the 6-position on the naphthalene ring considerably increased the inhibitory activity toward IgE production with an IC50 of 8.3 nM (36). The potency of 31 and 36 was retained when hydrocortisone or lipopolysaccharide was used instead of alpha-CD40 and IL-10 as costimulatory factors with IL-4, implying that these compounds may interfere with signal transduction between IL-4/IL-4 receptor cognition and genetic transcription that induce class-switching of immunoglobulin in B cells. These novel naphthalene derivatives are thus excellent candidates for further investigation with a view toward a therapeutic remedy against IgE-mediated allergic diseases.

Interleukin (IL)-4-independent immunoglobulin class switch to immunoglobulin (Ig)E in the mouse

Immunoglobulin (Ig) class switching in B cells is regulated by stimuli transduced by cytokines and cell-cell contact. Among these stimuli, interleukin (IL)-4 has been considered an absolute prerequisite for class switching to IgE in the mouse. Here we report that IL-4-deficient (IL-4-/-) and wildtype mice had comparably elevated serum IgE levels during the course of a murine retrovirus-induced immunodeficiency syndrome, MAIDS. IgE switching in IL-4-/- mice was also induced by injection of anti-IgD antibody. Treatment with anti-IgD induced germline epsilon (g epsilon) transcripts with comparable efficiency in IL-4-/- mice and controls, but the levels of productive epsilon transcripts (p epsilon) were lower by a factor of 200 and serum IgE levels were lower by a factor of 300 in IL-4-/- mice as compared with controls. Induction of g epsilon after anti-IgD treatment of IL-4-/- mice was unaffected by simultaneous treatment with monoclonal antibodies to IL-4 and IL-4 receptor alpha chain. Infection of IL-4-/- mice with Nippostrongylus brasiliensis, a potent stimulus for IgE production, resulted in induction of g epsilon transcripts; however, p epsilon transcripts were barely detectable and serum IgE was not detected. These findings establish a novel IL-4-independent pathway for IgE switching in the mouse that is strongly activated in retroviral infection but weakly in nematode infection. This pathway appears to be dependent on distinct factors that separately control induction of g epsilon transcription and switch recombination to p epsilon.

Exclusive expression of the Gs-linked prostaglandin E2 receptor subtype 4 mRNA in mononuclear Jurkat and KM-3 cells and coexpression of subtype 4 and 2 mRNA in U-937 cells

Prostaglandin E2 (PGE2) is regarded as a potent regulator of the immune system. It can regulate apoptosis in mononuclear cells and modulate the cytokine secretion pattern from T-helper cell subpopulations via an increase in cyclic AMP (cAMP). Of the 4 PGE2 receptor subtypes (EP1-EP4) that are defined pharmacologically by their affinity to subtype-specific ligands and their coupling to G proteins, EP2 and EP4 receptors couple to Gs. It is as yet unknown which of these two receptor subtypes mediates the immunomodulatory effects. By quantitative RT-PCR, the mRNA for EP4 receptors was demonstrated and quantified in the human mononuclear cell lines Jurkat, KM-3 and U-937. However, EP2 receptor mRNA was only present in U-937 cells and was 100-fold less abundant than EP4 receptor mRNA. PGE2 increased cAMP formation with an ED50 of 50-100 nM in all cell lines. cAMP formation was inhibited by the EP4R-specific antagonist AH23848. Since AH23848 inhibited PGE2-induced cAMP formation in U-937 cells to a similar extent as in Jurkat and KM-3, EP2 receptors seem to play, if any, only a secondary role for the PGE2-mediated cAMP formation in U-937 cells.

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.

Dietary Juniperis virginiensis seed oil decreased pentobarbital-associated mortalities among DBA/1 mice treated with collagen-adjuvant emulsions

The propensity of the fatty acid 5,11,14-eicosatrienoic acid (5,11,14-ETA) to replace arachidonic acid in cell membranes, and its inability to be converted to bioactive eicosanoids, suggest that it may be useful in the treatment of autoimmune disorders. Previously, dietary application of oils extracted from 5,11,14-ETA-rich Platycladus orientalis delayed the onset of autoimmune disease in New Zealand Black mice. To gain more knowledge of the efficacy of this fatty acid toward alleviating immunological disorders, a similar oil was used to examine its effects on collagen-induced arthritis in DBA/1 mice, a model characterized by synovial proliferation and joint infiltration by inflammatory cells. Mice were fed AIN76A diet supplemented with 4% (w/w) of either an oil extracted from the seeds of Juniperis virginiensis (0.4% 5,11,14-ETA); a control oil consisting of equal parts olive, linseed and safflower oils; fish oil (90% fish oil and 10% safflower oil); or safflower oil. Mice were immunized with three injections of collagen-adjuvant emulsions, the first injection was intradermal, and the two subsequent injections were intraperitoneal. Mortalities were recorded following a secondary pentobarbital administration intraperitoneally. Mice from the J. virginiensis group had the lowest mortalities (25%) while safflower oil-fed mice had the highest (59%; p < 0.05). While the J. virginiensis group had the lowest mean CD4/CD8 T lymphocyte ratio, the fish oil group had the highest. These observations suggest that manipulation of eicosanoid production by different dietary lipids had different effects on immune responses, possibly through alterations in T lymphocyte subsets. Hypothetically, a downregulation of prostaglandin E2 release could increase the ratio of T helper 1 to T helper 2 lymphocytes and thereby modulate anaphylactic responses. Also, lowered pro-oxidant status may decrease CD4/CD8 T cell ratios and modify immune function.

A new assay system detecting antibody production and delayed-type hypersensitivity responses to trinitrophenyl hapten in an individual mouse

A new assay system detecting antibody production and delayed-type hypersensitivity (DTH) responses to trinitrophenyl hapten in an individual mouse (AS-DAD) was established. BALB/c mice were immunized intraperitoneally with varying amounts of 2,4,6-trinitrophenylated sheep red blood cells (TNP-SRBC) on day 0. Venous blood was collected on days 2, 4, 6, 8 and 10. Levels of anti-TNP IgM and IgG serum were assayed by enzyme-linked immunosorbent assay (ELISA). After series of bleeding the mice were challenged with 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution in the footpad on day 14. Footpad swelling was measured 24 or 48 h after the challenge. Peak responses of the anti-TNP IgM and IgG production were detected 4 or 6 days after the immunization with 10(9) TNP-SRBC. Maximum DTH response was also observed with 10(9) TNP-SRBC 24 h after the challenge on day 14. The antibody and DTH responses were also induced in other normal inbred strains such as C3H/He and DBA/1 but not BALB/c nu/nu mice. To evaluate AS-DAD in immunopharmacological studies, various immunomodulating agents were examined in BALB/c mice by subcutaneous administration on days 0, 1, 2 and 3. Cyclosporin or cyclophosphamide at 100 mg/kg/day completely inhibited not only the anti-TNP IgM and IgG production but also the TNP-specific DTH response. Prednisolone at 0.5 mg/kg/day had no significant effect on the IgM and IgG production, whereas it inhibited the TNP-specific DTH response. Interestingly, histamine-added mouse gamma-globulin at 150 MG/kg/day clearly enhanced the anti-TNP IgM and IgG production, while it showed a suppressive effect on the TNP-specific DTH response. Levamisole at 5.0 mg/KG/day showed suppressive effects on the anti-TNP IgG production without affecting the IgM production and the DTH response. These results suggest that AS-DAD is useful for evaluating the immunopharmacological action of various agents.

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)

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.

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.

Interferon (IFN)-alpha, IFN-gamma, interleukin (IL)-2, and arachidonic acid metabolites modulate IL-4-induced IgE synthesis similarly in healthy persons and in atopic dermatitis patients

The role of cytokines and arachidonic acid metabolites in the regulation of IgE production in healthy persons and in atopic dermatitis patients with elevated IgE levels was studied. Interleukin-4 (IL-4) induced IgE production in peripheral blood mononuclear cells (PBMCs) of all donors, and no significant difference was found between the amounts of IgE produced by healthy persons and atopic dermatitis patients. Similarly, recombinant interferon (IFN)-alpha and IFN-gamma, as well as IL-2, inhibited IL-4-induced IgE production to a similar extent in both study groups. To evaluate the role of arachidonic acid (AA) metabolites in the regulation of IgE production, we added indomethacin, an inhibitor of the cyclooxygenase pathway, or nordihydroguaiaretic acid (NDGA), an inhibitor of the lipoxygenase pathway, to IL-4-treated cultures. Both indomethacin and NDGA strongly inhibited IL-4-induced IgE production. They also inhibited IL-4-induced IgG4 synthesis. No significant difference in the amount of inhibition was found between the two study groups. We were unable to restore the NDGA-induced inhibition of IgE-production by adding leukotrienes B4, C4, D4, or 5-HETE to the NDGA-treated cultures. PGE2 also failed to restore the indomethacin-mediated inhibitory effect. Consequently, NDGA- and indomethacin-mediated inhibitory effects do not appear to be mediated by any single factor studied. Collectively, our results show IFNs and IL-2 to be similar in effect in the modulation of IL-4-induced IgE synthesis in healthy and atopic persons.(ABSTRACT TRUNCATED AT 250 WORDS)

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).

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.

Selective regulation of antigen-specific IgE response by cyclic AMP level in murine lymphocytes

We have reported that prostaglandin E2 (PGE2) is a selective stimulator of the antigen-specific IgE response [6]. Because PGE2 is known to elevate intracellular cAMP, we investigated the regulatory role of cAMP in the production of antigen-specific IgE. Anti-TNP IgE response was induced by stimulating TNP-KLH-primed BALB/c spleen cells with the same antigen in vitro. Addition of 10-100 microM dibutyryl cAMP (DBcAMP) to the lymphocyte culture resulted in a 2-3-fold increase in anti-TNP IgE response without affecting the production of anti-TNP IgG1 or IgM. Forskolin, a stimulator of adenylate cyclase, also specifically augmented the IgE response. In contrast, 2',5'-dideoxyadenosine, an inhibitor of adenylate cyclase, suppressed IgE production in an isotype-specific manner. These results suggest that IgE synthesis can be selectively modulated by intracellular cAMP level. Enhancement of IgE production by DBcAMP was observed, particularly in highly primed spleen cells, suggesting that IgE-committed B cells are subjected to regulation by cAMP.

A new view of prostaglandin E regulation of the immune response

Prostaglandins, particularly those of the E series, are widely regarded as immunosuppressive products of eukaryotic cells that can downregulate many aspects of B- and T-cell function. In this article, Richard Phipps and colleagues present a different concept of E series prostaglandins, based on recent evidence supporting a role for prostaglandins as potentiators of immunoglobulin class switching and of the synthesis of selected cytokines and cytokine receptors.

The lack of receptors for atrial natriuretic peptides on human monocytes prevents a rise of cGMP and induction of tumor necrosis factor-alpha synthesis

Freshly harvested human monocytes were shown to produce tumor necrosis factor-alpha (TNF-alpha) in response to exogenously added or sodium nitroprusside-generated cGMP. In contrast, atrial natriuretic peptide (ANP) that acts by elevating cGMP in a variety of cells, was incapable of inducing TNF-alpha synthesis. This failure was due to a lack of ANP receptors and thus, to the inability of ANP to raise cGMP in human monocytes.