Effect of recombinant human interleukin 4 on spontaneous in vitro human IgE synthesis

Respiratory syncytial virus may be a pathogen in allergic conjunctivitis

PURPOSE

The host response to allergens appears to be regulated by T helper type 2 cell patterns of local cytokine production. We hypothesized that respiratory syncytial virus (RSV) infects the normal conjunctival epithelium and produces interleukin (IL)-4, causing a local allergic reaction.

METHODS

Giemsa staining, immunocytochemical study, flow cytometric analysis, and reverse-transcriptase polymerase chain reaction (RT-PCR) were performed on tear and cytology samples from individuals with allergic and postoperative conjunctivitis. Histamine was assayed by radioimmunoassay, and IL-4 by enzyme-linked immunosorbent assay.

RESULTS

The total number of cells collected by brush cytology did not differ between allergic and postoperative conjunctivitis. The levels of IL-4 and histamine in the specimens and mean IL-4 tear level were significantly increased in patients with allergic conjunctivitis. Cytocentrifuge preparations contained conjunctival epithelial cells with lymphocytes (a few CD3- and CD4-bearing cells), mast cells, eosinophils, and higher human leukocyte antigen (HLA)-DR expression in allergic patients. RT-PCR analysis showed that samples from allergic conjunctivitis expressed increased transcripts of IL-4 and IL-13. A higher percentage of RSV sequences were detected in allergic patient samples. Immunocytochemical study and RT-PCR showed that epithelial cells were infected with RSV. Average concentrations of IL-4 in culture supernatants were higher than levels in uninfected cells.

CONCLUSIONS

These results suggest that the clinical features of human allergic conjunctivitis are associated with T helper type 2 cytokine expression. RSV in conjunctival epithelial cells may be an environmental pathogen in allergic conjunctivitis.

Development of IgG1 and IgG4 antibodies against beta-lactoglobulin and ovalbumin in healthy and atopic children

BACKGROUND

The IgG responses to food antigens are preferentially restricted to the IgG1 and IgG4 subclasses. Increased levels of IgG1 and IgG4 antibodies against food allergens have been reported in girls and adults with current atopic eczema.

OBJECTIVE

To study the relation between the levels of IgG1 and IgG4 antibodies against beta-lactoglobulin and ovalbumin and the development of atopic disease.

MATERIAL AND METHODS

Atopic symptoms were recorded in 36 girls from birth to 7 years of age. Blood samples were taken at 3 and 8 months and at 2, 4, and 7 years. IgG1 and IgG4 antibodies were measured by ELISA.

RESULTS

Anti-beta-lactoglobulin IgG1 was detected at all ages, peaking at 8 months. Anti-beta-lactoglobulin IgG4 antibodies were detected in 18 to 29 girls at different ages and the antibody levels peaked at 2 years. The levels of anti-beta-lactoglobulin IgG1 were lower in atopic, as compared with healthy individuals at 4 and 7 years (P < .01 and P < .05) and lower anti-beta-lactoglobulin IgG4 antibody levels were found in atopic individuals (P < .05) at 4 years. Anti-ovalbumin IgG1 antibodies were detected in 3/35 girls at 3 months and in 16/35 to 26/35 girls later in life. The number of positive samples and antibody levels peaked at 2 years. Anti-ovalbumin IgG4 positive samples increased from 4/33 at 8 months to 30/32 at 7 years. The levels increased up to 2 years and then remained stable. The anti-ovalbumin IgG1 antibody levels were lower in atopic girls at 4 years (P < .05), while the anti-ovalbumin IgG4 antibody levels were similar at all ages.

CONCLUSION

An early IgG1 response and later appearing IgG4 antibodies to the two food antigens beta-lactoglobulin and ovalbumin are common during the first years of life. The levels were similar in the nonatopic and the atopic girls up to four years; then they tended to be lower in the first group.

Measurement of interleukin-4 and histamine in superficial cells of conjunctiva in patients with allergic conjunctivitis

Interleukin 4 (IL-4) may play a role in the development of allergic disease. We questioned whether IL-4 related phenomenon occurred on the surface of the conjunctiva during allergic conjunctivitis. Ten patients with cedar pollen-allergic conjunctivitis and 10 patients with postsurgical conjunctivitis were enrolled in this study. Cells were collected by brush cytology from the upper palpebral conjunctiva. After the cells were cultured for 24 hours, the levels of IL-4, IgE, and histamine were measured in the supernatants. An ELISA was used for histamine and a highly sensitive sandwich ELISA for IL-4 and IgE. Conjunctival cells were also stained and fixed by May-Grunwalds stain solution. The number of superficial cells, especially lymphocytes, were compared in the two groups. The total number of cells collected by brush cytology did not differ in allergic vs., postsurgical conjunctivitis. Lymphocytes were similarly present in such specimens. The levels of IL-4 (p = 0.01) and histamine (p = 0.02) significantly increased in the specimens from patients with allergic conjunctivitis, although IgE was not detected in both groups. There was a correlation between the level of IL-4 and histamine (p = 0.0001). Conjunctival cells in allergic conjunctivitis produced a larger amount of IL-4 and histamine for cedar pollen compared to the postsurgical conjunctivitis. As with other allergic diseases, IL-4 may play a role similar to that of histamine in the development of allergic conjunctivitis.

Dual action of IL-4 on mite antigen-induced IgE synthesis in lymphocytes from individuals with bronchial asthma

Polyclonal IgE synthesis was efficiently induced by Dermatophagoides farinae (Df) antigen in freshly derived peripheral blood lymphocytes from mite-sensitive individuals with bronchial asthma. The in vitro IgE production was significantly correlated with total serum IgE values. The induced IgE synthesis was inhibited in a dose-dependent manner by antibodies to IL-4, indicating a role for endogenous IL-4. Although IL-4 alone increased IgE production, high concentrations (1-100 U/ml) of the cytokine inhibited Df antigen-stimulated production of IgE. However, low concentrations (0.001-0.01 U/ml) of IL-4 significantly enhanced Df antigen-induced IgE production, as did high doses of IL-4 when endogenous IL-4 was neutralized by antibodies to IL-4. Two other cytokines, IL-10 and interferon-gamma (IFN-gamma), showed contrasting actions, as judged from experiments with, exogenous cytokine and anti-cytokine antibodies: IL-10 enhanced and IFN-gamma inhibited Df antigen-induced IgE synthesis. Thus, mite-stimulated IgE production in lymphocytes from individuals with bronchial asthma appears to be regulated by at least three cytokines: IL-4, IL-10, and IFN-gamma.

Lol p I-specific IgE and IgG synthesis by peripheral blood mononuclear cells from atopic subjects in SCID mice

BACKGROUND

The development of an animal model representative of the in vivo situation of human atopic diseases is always of interest for a better understanding of IgE production and regulation. Along these lines, mice with severe combined immunodeficiency (SCID mice) engrafted with lymphocytes from atopic subjects might be a suitable model for such studies.

OBJECTIVE

This study aims to analyze the production of Lol p I-specific IgE and IgG antibodies in SCID mice after transplantation of human peripheral blood mononuclear cells from atopic patients sensitive to grass pollens and from nonatopic donors.

METHODS

Peripheral blood mononuclear cells were transplanted into SCID mice, which were then challenged with Lol p I, and antibody responses (IgG and IgE) were analyzed over a 6-week period.

RESULTS

Total IgG antibody was measured in each mouse serum after transplantation. Also, most mice (regardless of whether donors were atopic) that were challenged with Lol p I produced specific IgG antibody. Total IgE antibody production was observed only in mice grafted with cells from atopic patients. Lol p I-specific IgE antibodies were also produced after immunization with Lol p I. Although IgG antibody/response tended to plateau, the IgE antibody response increased until it peaked and declined thereafter. Interferon-gamma was detected in sera from mice producing IgE antibody, which supports a possible role of interferon-gamma in the decrease of IgE response.

CONCLUSION

This study suggests that the SCID mouse model could represent an interesting approach to studying specific, total IgG and IgE antibody production, and ultimately their regulation.

Regulation of IgE production from human mononuclear cells by beta 2-adrenoceptor agonists

The present study examined the effect of beta 2-adrenoceptor agonists on the interleukin-4 (IL-4)-driven IgE production and on the possible mechanisms of action of these compounds. We present evidence that salbutamol and fenoterol potentiated the IL-4-induced IgE production by human peripheral blood mononuclear cells (PBMC). No significant effect of incubation in the presence of beta 2-adrenoceptor agonists on IgG, IgA and IgM production was observed. Salbutamol and fenoterol inhibited interferon-(IFN)-gamma production by PHA-activated human PBMC suggesting that the blockade of the production of this cytokine could possibly explain the enhancement of IgE production. Salbutamol and fenoterol potentiated the IL-4-induced production of sCD23 whereas no effect on CD23 expression was observed. The potentiating effect of salbutamol on IgE production was blocked by two antagonists of beta 2-adrenoceptor, namely butoxamine and D,L-propranolol, suggesting a beta-adrenoceptor-mediated event. These results demonstrate that beta 2-adrenoceptor stimulation results in an increase in IgE production by human B lymphocytes.

Synthetic glucocorticoids potentiate IgE synthesis. Influence of steroid and nonsteroid hormones on human in vitro IgE secretion

Recently, hydrocortisone (HC) has been shown significantly to enhance interleukin-4 (IL-4)-induced in vitro IgE synthesis. For investigation of possible effects of synthetic corticosteroids but also of effects of other important human hormones, peripheral blood mononuclear cells (PBMC) were incubated with IL-4 and various concentrations of the hormones. IgE secreted in the supernatant was determined after a 14-d culture period. Like HC, all synthetic corticosteroids potentiated IgE secretion. A minor effect was noted for the mineralocorticoid aldosterone. No modulating effect on IL-4-induced IgE formation was observed for adrenocorticotropic hormone (ACTH), somatotropin (STH), thyroid-stimulating hormone (TSH), triiodothyronine, thyroxine, epinephrine, noradrenaline, insulin, and glucagon.

Chronic lymphocytic leukemia cells induce non-T cells to produce IgE in the presence of interleukin-4

Mononuclear cells from peripheral blood and bone marrow from patients with chronic lymphocytic leukemia (CLL) were cultured with interleukin-4 (IL-4) alone or with IL-4 and hydrocortisone (HC) in order to induce IgE synthesis. From a total of 29 experiments with the cells of 17 different donors an IgE secretion was observed only twice. Even in those two cases the IgE was found to be not monoclonal. The additional stimulation of CLL cells by polyclonal B cell activators induced IgM but not IgE production. When CLL cells were cocultured with monocyte-enriched cell preparations (M phi) in the presence of IL-4 and HC, a substantial IgE secretion could be obtained, which again consisted of both IgE kappa and IgE lambda. Since the irradiation of the M phi but not of the CLL cells abolished the formation of IgE, it is likely that the IgE production resided in the contaminating B cell population of the M phi. When the M phi were replaced by T cell-depleted peripheral blood mononuclear cells (non-T cells), irradiated as well as formaldehyde fixed CLL cells were able to stimulate non-T cells to secrete IgE in the presence of IL-4 or to potentiate IL-4- and HC-induced IgE formation. Furthermore, the coculture of irradiated pure CLL cells and purified B cells induced not only IgE but also IgG and IgM production and B cell proliferation in the presence of lymphokines. Our findings suggest that CLL cells, contrary to current opinion, cannot be induced to produce IgE.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of interleukin-4 and interferon-gamma on the secretion of IgG4 from human peripheral blood mononuclear cells

Whereas IgE antibodies are linked with allergy, IgG4 antibodies may reflect the state of immunity and protection against a particular antigen. It has been shown that interleukin (IL)-4 is required for induction of IgE synthesis. In order to elucidate the role of IL-4 in the production of IgG4 and to compare IgG4 and IgE regulatory processes, we quantified these immunoglobulin isotypes after in vitro culture of peripheral blood mononuclear cells (PBMC) in the presence of IL-4. The production of IgG4 was increased by IL-4 under the same conditions which are optimal for IgE production but not among PBMC from all donors, depending on the magnitude of spontaneous IgG4 secretion: IL-4 was effective only when the spontaneous secretion of IgG4 was < 7% of the total IgG secretion; it had no effect when spontaneous IgG4 production was > 7% of total IgG. The IL-4-induced IgE response was consistently obtained when IgG4 was < 7% of total IgG but was markedly diminished or absent when IgG4 was > 7% of total IgG. If Staphylococcus aureus strain Cowan 1 (SAC) was present during the 48-h preincubation step, spontaneous IgG4 production was increased, but the stimulatory effect of this mitogen on immunoglobulin production, including IgG4, was markedly blocked by the addition of IL-4. In contrast, IL-4-induced IgE synthesis was strongly blocked by the presence of SAC. Finally, secretion of IgG4 (spontaneous and IL-4-induced) was suppressed among cells from most donors by interferon-gamma (IFN-gamma).(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of IgE and IgG1 in human B cell cultures with staphylococcal superantigens: role of helper T cell interaction, resistance to interferon-gamma

Non-antigen-specific activation of human B lymphocytes for IgE production in vitro requires the presence of interleukin 4 and non-cognate physical interaction with T cells. The latter can be replaced by antibodies directed against the B cells' CD40 structure. Antigen-specific induction of immunoglobulin responses, including IgE, is difficult in human lymphocyte cultures. Thus, we developed a model system which might resemble physiological B lymphocyte stimulation by antigen. Co-cultures of purified tonsillar B cells from normal donors with non-HLA matched T helper clones obtained from the skin of atopic dermatitis patients produced significant levels of IgE and IgG1 after stimulation with appropriate types of staphylococcal exotoxins, provided that IL-4 was also induced in the T cells. Such responses were further enhanced by addition of low doses of anti-CD40 antibodies. Concentrations of anti-CD40, optimal for stimulation of B cells in the absence of T helper lymphocytes, were less effective in this regard and even inhibitory in some experiments. Most powerful immunoglobulin induction was observed when the cultures were spiked with low amounts of IL-4 and anti-CD40 which did not elicit substantial immunoglobulin production in the absence of the staphylococcal exotoxins. Induction of IL-2 in T/B cell cultures by superantigens without production of appreciable quantities of IL-4 provoked considerable IgG1 titer but no IgE. High amounts of interferon-gamma generated by the T cells in vitro in the presence of superantigens did not appear to interfere with immunoglobulin induction. Addition of recombinant interferon at the beginning of the culture period at doses which effectively suppressed IL-4 plus anti-CD40 induced immunoglobulin responses did not inhibit T helper and superantigen dependent B cell activation. Superantigen mediated B cell stimulation for immunoglobulin production was dependent on cell-cell contact. The experimental results presented suggest that this cellular interaction did not necessarily involve T-B cell bridging by superantigens.

Seasonal enhancement of IL-4 induced IgE synthesis by peripheral blood mononuclear cells of atopic patients

The role of IL-4 on IgE synthesis has been well established. IL-4 has been shown to promote IgE production by B cells from atopic and non-atopic donors. In this study, the effects of natural exposure to pollens on IL-4-induced IgE synthesis by peripheral blood mononuclear cells of atopic and non-atopic donors were examined. The results confirm production of IgE in an IL-4 dose-dependent manner by PBMC cultures of these two groups. When cultures were performed out of the pollen season, following stimulation by IL-4, no significant differences was observed between the levels of IgE produced by PBMC of atopic and non-atopic donors. In contrast, upon natural exposure to pollens, significant higher levels of IgE were measured in the atopic group than in the non-atopic one. These results show that the pollen season influences the IL-4-induced IgE synthesis by PBMC of allergic patients and are in keeping with seasonal rise of specific IgE antibodies.

Lol p I-induced IL-4 and IFN-gamma production by peripheral blood mononuclear cells of atopic and nonatopic subjects during and out of the pollen season

The reciprocal effects of IL-4 and IFN-gamma on IgE synthesis have been well established. It has also been shown that these two lymphokines are secreted by different subsets of CD4+ T cells (TH1 and TH2), and that TH2 helper T lymphocytes could be involved in the pathophysiology of allergic diseases. But little is known about the effects of an allergen on the profile of lymphokine synthesis by human peripheral blood mononuclear cells (PBMCs) of allergic and nonallergic subjects. We studied the production of IL-4 and IFN-gamma by PBMCs of atopic and nonatopic donors after in vitro stimulation by the group 1 allergen from Lolium perenne pollen (Lol p I), during and out of the grass pollen season. On natural exposure to pollen, Lol p I-induced IL-4 production was observed only with atopic donors (6 of 8), whereas the synthesis of IFN-gamma was observed for all nonatopic donors (7 of 7) and most allergic patients (5 of 7). At the time of the study, higher amounts of IFN-gamma were produced by PBMCs of nonatopic donors than by PBMCs of atopic patients. Out of the pollen season the production of IL-4 was not observed either by atopic (n = 11) or by nonatopic subjects (n = 5). On the other hand, IFN-gamma was produced by PBMCs of most subjects (atopic, 10 of 11; nonatopic, 5 of 5), but at the time of the study no difference was observed between the two groups. These results show that Lol p I induces different profiles of IL-4 and IFN-gamma production by PBMCs of atopic and nonatopic subjects. In atopic subjects this profile of lymphokine synthesis is influenced by the natural exposure to pollen, which is in keeping with the seasonal rise of IgE antibodies.

A specific feedback by anti-IgE autoantibodies on the cytokine network in allergy

During recent years we have shown that anti-IgE antibodies can have different biological functions. Depending on their epitope specificity they can be anaphylactogenic or not, they interfere with IgE binding to its receptor or not, and they enhance or inhibit IgE synthesis. Therefore we propose a theoretical model implying that anti-IgE autoantibodies are specific feed back molecules that neutralize IgE induced by the cytokine network. In the normal individual this system would be beneficial, where as the atopic individual, due to differences in its B cell repertoire, will produce the wrong type of anti-IgE antibody. The wrong type of anti-IgE antibody may even aggravate the disease as some of these autoantibodies may induce IgE synthesis or trigger effector cells that in turn generate a Th2 like cytokine pattern.

The role of T cells and the effect of hydrocortisone on interleukin-4-induced IgE synthesis by non-T cells

The role of T cells for IL-4-induced IgE synthesis by peripheral blood mononuclear cells (PBMC) was investigated. The removal of monocytes from PBMC abolished IL-4-induced IgE synthesis. When PBMC were separated into T and non-T cells, non-T cells alone were not able to secrete significant amounts of IgE in the presence of IL-4. Depending on the separation procedure, the reconstitution of non-T cells with T cells prepared by rosetting did not restore IgE secretion, whereas T cells obtained by the use of anti-CD3 antibodies could co-induce IgE formation. However, when the T cells were first irradiated, large amounts of IgE were produced, which strongly exceeded those found in unseparated PBMC cultures. IL-4-induced IgE synthesis was also obtained in co-cultures of formaldehyde-fixed T cells with non-T cells. Furthermore, not only autologous but also allogeneic T cells, which have been irradiated or fixed, could provide the costimulatory effect on IgE formation by non-T cells in the presence of IL-4. Mitogenically pre-activated T cells, however, were not able to support IgE synthesis. Hydrocortisone (HC) potentiated the IL-4-induced IgE synthesis by PBMC and enabled non-T cells to secrete IgE in the presence of IL-4. Adding both HC and T cells led to a marked synergistic effect on IL-4-induced IgE production. We conclude that monocytes are required for the induction of IgE synthesis in PBMC in addition to T cells and IL-4. Our results support the view that the T cell signal is delivered via cognate and non-cognate T/B cell membrane interaction. Furthermore, active and proliferating T cells rather suppress IgE synthesis. Finally, HC appears to be a potent alternative stimulus, which bypasses the necessity for T cells in IL-4-induced IgE formation.

Variable effects of chemical allergens on serum IgE concentration in mice. Preliminary evaluation of a novel approach to the identification of respiratory sensitizers

A wide variety of chemicals may induce allergic contact dermatitis (contact sensitivity). Some chemical allergens may, in addition, cause respiratory sensitization. Topical exposure of mice to contact and respiratory chemical sensitizers results in the initiation of divergent immune responses characteristic of preferential activation of different functional subpopulations of T helper (TH) cells. In the present study we have sought to make use of these differences, particularly differences in the ability of contact and respiratory allergens to provoke IgE responses, and to question whether opportunities exist for the identification of chemicals with the potential for respiratory sensitization. We have examined alterations in the serum concentration of IgE following topical exposure of mice to seven chemical allergens; trimellitic anhydride (TMA), phthalic anhydride, diphenylmethane-4,4'-diisocyanate (MDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), isophorone diisocyanate (IPDI), oxazolone and 2,4-dinitrochlorobenzene (DNCB). Three of these--TMA, phthalic anhydride and MDI--are known human respiratory sensitizers. The other four--HMDI, IPDI, oxazolone and DNCB--appear not to cause respiratory allergy, or at least have a very limited potential to do so. At the concentrations tested, exposure to all chemicals caused a lymphocyte proliferative response in lymph nodes draining the site of application. However, exposure only to TMA, phthalic anhydride and MDI resulted in a substantial increase in the concentration of serum IgE. Treatment with HMDI and IPDI failed to induce any change in serum IgE concentration. DNCB and oxazolone caused only small and transient elevations of IgE that were considerably less marked than those observed with respiratory sensitizers.(ABSTRACT TRUNCATED AT 250 WORDS)

IL-4 and transforming growth factor-beta suppress human immunoglobulin secretion in vitro by surface IgD- B cells

The effect of IL-4 and transforming growth factor-beta (TGF-beta) on immunoglobulin secretion in vitro by peripheral blood mononuclear cells (PBMC) or purified B cells activated with murine EL4 thymoma cells and phorbol myristate acetate (PMA) was investigated. As previously reported, IL-4 induced IgE and IgG4 secretion by B cells in PBMC preparations and B cells activated with EL4 cells and PMA. However, when B cells, either in PBMC preparations or purified and activated with EL4 cells and PMA, spontaneously secreted large quantities of immunoglobulin, IL-4 suppressed the immunoglobulin secretion of all isotypes. IL-4 also suppressed the IgE secretion by B cells from an atopic dermatitis patient. This suppressive effect was not reversed by adding IL-2 or interferon-gamma (IFN-gamma) to the cultures. We also showed that TGF-beta suppressed the immunoglobulin secretion by purified B cells activated by EL4 cells and PMA. To investigate whether IL-4 or TGF-beta suppressed immunoglobulin secretion by in vivo 'switched' and isotype-committed B cells, sIgD- B cells were isolated, activated with EL4 cells and PMA and cultured with IL-4 or TGF-beta. Such activated B cells secreted large quantities of IgG1, IgG2, IgG3, IgA1, IgA2 and IgM, and IL-4 and TGF-beta suppressed all these isotypes by greater than 80%. The data demonstrated that IL-4 and TGF-beta suppress immunoglobulin secretion in vitro by in vivo isotype-committed sIgD- B cells, suggesting that these lymphokines may play a down-regulatory role on differentiated isotype-committed B cells in an isotype-unrestricted manner. The data also showed that IL-4 and TGF-beta acted directly on isolated B cells.

Mechanism of pokeweed mitogen inhibition of rhIL-4-induced human IgE synthesis

Pokeweed mitogen (PWM) suppressed rhIL-4-induced IgE synthesis in a concentration-dependent manner. When rhIL-4 was present from Day 0, PWM added to cultures on Day 0 or 3 inhibited MNC IgE synthesis but not when it was added on Day 6 or later. The concentration of interferon-gamma (IFN-gamma) in MNC culture supernatants varied directly with the quantity of PWM added. Conversely, rhIL-4-stimulated MNC culture IgE concentrations varied inversely with the dose of PWM added and the IFN-gamma concentrations induced. The addition of a rabbit polyclonal neutralizing anti-human IFN-gamma antibody to rhIL-4 plus PWM-stimulated cultures partially or completely reversed PWM-induced inhibition of rhIL-4-induced IgE synthesis. PWM failed to inhibit rhIL-4-induced IgE synthesis by isolated B cells cocultured with monocytes and T cells from a clone unable to produce IFN-gamma message or protein. These findings are consistent with the postulate that PWM inhibits rhIL-4-induced IgE synthesis by inducing the production of IFN-gamma.

Hyper-response of serum IgG1 to Staphylococcus aureus peptidoglycan in patients with hyper-IgE syndrome

The hyper-IgE (HIE) syndrome is characterized by high IgE serum levels, chronic dermatitis and recurrent infections. To determine whether an impairment of the antibody response to Staphylococcus aureus contributes to infections in this syndrome we measured total serum IgG subclass, specific IgG1 and IgG2 levels against peptidoglycan (PG), the immunodominant cell wall component of S. aureus and serum opsonic activity to PG. Of the 14 patients with HIE syndrome, nine had increased level of serum IgG1 and six had IgG2 subclass deficiency. In regard to specific response of IgG1 and IgG2 antibodies to PG, patients were divided into five groups related to ages and compared with 10 control subjects for each age cohort. Patients with HIE syndrome had significant high levels of serum-specific IgG1 to PG and significant decreased levels of serum-specific IgG2 to PG in all five groups. Additionally, serum opsonic activity in patients was significantly higher than that in normal control subjects. It is concluded that IgG2 deficiency or poor IgG2 antibody response to S. aureus is not the explanation of the abnormal susceptibility to S. aureus infections of HIE patients.

Effect of recombinant human erythropoietin on human IgE production in vitro

Recombinant human erythropoietin enhanced spontaneous IgE production (200-300% enhancement) in cultures of peripheral blood mononuclear cells (MNC) from atopic patients. In contrast, IgG and IgA production were only slightly enhanced (30-50% enhancement), and IgM production was not affected by erythropoietin. The enhancement of IgE production by erythropoietin was indirect since it required T cells and monocytes. However, erythropoietin effect was specific since enhancement was blocked by anti-erythropoietin antibody but not by control antibody. Interleukin-4 (IL-4) also enhanced spontaneous IgE production from atopic MNC. However, the enhancing effect by erythropoietin is different from that by IL-4, since the erythropoietin effect was not blocked by anti-IL-4 antibody, and conversely IL-4 effect was not blocked by anti-erythropoietin antibody. In contrast to the enhancing effect on atopic MNC, erythropoietin failed to induce IgE production in cultures of MNC from normal donors while IL-4 induced IgE production from normal MNC. However, when normal MNC were pre-incubated with IL-4, erythropoietin enhanced IgE production from IL-4-pre-incubated MNC. Moreover, B cells separated from IL-4-pre-incubated MNC produced IgE which was enhanced by erythropoietin. However, this effect required T cells and monocytes. These results indicate that erythropoietin could regulate ongoing IgE production in vitro by T cell- and monocyte-dependent mechanisms.

Human transferrin allows efficient IgE production by anti-CD3-stimulated human lymphocytes at low cell densities

A solid-phase-coupled anti-CD3 T cell activation system was used to study the regulation of human IgE production in vitro. Using 5000 peripheral blood lymphocytes from healthy donors, containing 10%-20% B lymphocytes and no monocytes. IgE was produced very efficiently on a per cell basis. A key observation was that apart from interleukin (IL) 4, human transferrin was essential for IgE production. Furthermore it was found that IgE was produced at low densities only; at higher cell concentrations IgE production was completely abrogated, whereas IgM production increased with increasing cell density. This inhibition at higher cell densities is probably mediated by IL2. Addition of low amounts (6 U/ml) of IL2 strongly enhanced IgE and IgM production at low cell densities, but higher concentrations of IL2 (50 U/ml) were strongly inhibitory for IgE production.

The response of human B cells to interleukin 4 is determined by their stage of activation and differentiation

The effect of purified recombinant human interleukin 4 (IL-4) on proliferation and IgM secretion of normal and malignant human B cells was studied. IL-4 was found to co-stimulate the proliferation of splenic B cells in the presence of anti-Ig coupled to polyacrylamide beads (anti-Ig beads) for a period of 4 days. In contrast, IL-4 had little co-stimulatory effect on the proliferative response of splenic B cells to the more potent mitogen Staphylococcus aureus Cowan strain 1 (SAC). Moreover, IL-4 inhibited interleukin 2 (IL-2)-induced proliferation of cells co-stimulated with SAC. Mitogen-induced pre-activation of B cells in the presence of IL-4 resulted in a reduction in subsequent IL-2-induced IgM secretion without significantly affecting proliferation. Human B-cell tumours were also cultured over a 2-3 day period in the presence of anti-Ig beads plus IL-2, or IL-4 or both IL-2 and IL-4. IL-4 inhibited IL-2-induced proliferation in all cases of B-cell chronic lymphocytic leukaemia (B-CLL) and the majority of cases of low-grade lymphoma (LGL) and hairy cell leukaemia (HCL). These findings suggest that IL-4 has stimulatory actions on resting B cells, most evident in the presence of submaximal co-mitogenic signals, and inhibitory actions on activated B cells, especially antagonism of the effects of IL-2.

Human IgE mRNA expression by peripheral blood lymphocytes stimulated with interleukin 4 and pokeweed mitogen

Expression of human IgE mRNA by peripheral blood lymphocytes (PBL) and an IgE-producing myeloma cell line, U-266, was examined by Northern blot hybridization and compared with IgE levels in culture supernatants. A 2.35-kb IgE mRNA was detected in unstimulated atopic PBL and U-266 cells but not in normal PBL, and its levels correlated with IgE protein levels in the supernatant. Upon stimulation with interleukin 4, a new 1.75-kb transcript was revealed in both atopic and normal PBL but not in U-266 cells. Its expression did not correlate with IgE levels in the supernatant. Pokeweed mitogen also induced the expression of the 1.75-kb transcript without concomitant induction of IgE synthesis by normal PBL and even suppressed the spontaneous expression of the 2.35-kb transcript and IgE protein synthesis by atopic PBL. Interferon-gamma, which suppressed both the 2.35-kb transcript and IgE protein production, had no inhibitory effect on the 1.75-kb transcript. Expression of the 1.75-kb transcript was already high after 2 days of stimulation and peaked around day 4. The length of the transcript is smaller than that of mRNA coding for secreted human IgG and IgA and contains all four C epsilon exon sequences, suggesting it might be a truncated transcript without v region and might be a human counterpart of the murine germ-line C epsilon transcript.

The inductive effect of interleukin-4 on IgG4 and IgE synthesis in human peripheral blood lymphocytes

Using murine monoclonal antibodies against human IgG subclasses, specific and sensitive ELISAs assay to quantify the four human IgG subclasses in cell culture supernatants were established. The effect of human recombinant interleukin-4 (IL-4) on the regulation of IgG subclasses by normal peripheral blood lymphocytes was investigated. In addition to the enhancement of IgE synthesis, IL-4 preferentially induced IgG4 synthesis in vitro, whereas IL-4 had no effect on IgG1, IgG2, and IgG3 synthesis. IL-4-induced IgG4 production was blocked in a dose-dependent manner by recombinant interferon-gamma and anti-human IL-4 monoclonal antibody. Collectively, this data indicates that IL-4 plays an important regulatory role in both IgG subclass and IgE synthesis.

A cell culture system that enhances mononuclear cell IgE synthesis induced by recombinant human interleukin-4

A new culture system is described in which recombinant human interleukin-4 (rhIL-4) consistently induces the synthesis of large quantities of IgE by human blood mononuclear cells (MNC). Unfractionated MNC were cultured in complete Iscove's modified Dulbecco's medium (C-IMDM), composed of IMDM enriched with human transferrin, bovine insulin, bovine serum albumin, oleic acid, palmitic acid, linoleic acid, and fetal calf serum (FCS). Under these culture conditions, MNC from four donors synthesized mean quantities of IgE of 76 ng/ml at plateau after stimulation with rhIL-4 in concentrations ranging from 0.04 to 80 ng/ml (plateau rhIL-4 concentrations were 5 ng/ml or greater). In contrast, rhIL-4 failed to induce significant IgE synthesis at any of those doses of rhIL-4 in parallel MNC cultures performed in RPMI 1640 supplemented with FCS (RPMI 1640). Additional optimal conditions for the induction of IgE synthesis in this system were a MNC concentration of 1-2 X 10(6)/ml and a culture time of 18 days. Variability was noted in the amount of IgE produced by different donors (CV 0.22) and by the same donor when tested on different occasions (mean CV 0.21), but no donor's MNC failed to produce significant IgE in response to rhIL-4 when cultured in C-IMDM. The geometric mean IgE production induced by optimal IL-4 concentrations for the entire group of 16 subjects was 36.8 ng/ml IgE, with the lowest day 18 mean IgE concentration for any donor being 10.6 ng/ml and the highest 372.2 ng/ml. The enhanced rhIL-4-induced IgE synthesis supported by C-IMDM was due to the combined effects of the added enrichment factors and not to differences in the viabilities of MNC cultured in C-IMDM and RPMI 1640. This culture system will alleviate the problems of inconsistent and low quantities of IgE induced by IL-4 that confound most current culture systems used to examine rhIL-4-induced IgE synthesis. It will, thereby, facilitate further investigation of the regulation of human IgE synthesis.

Interleukin-4 induces both IgG4 and IgE secretion by peripheral blood B cells

Peripheral blood mononuclear cells (PBMCs) from healthy nonallergic donors were cultured with recombinant interleukin-4 (rIL-4), and the Ig of different isotypes was quantitated in the culture supernatants by radioimmunoassays. Recombinant IL-4 induced IgG4 and IgE secretion in a dose-dependent manner, whereas it had no consistent effect on the secretion of the other isotypes. In the absence of rIL-4, B cells in the PBMC preparations secreted less than 1 ng IgE/ml and a mean of 5 ng IgG4/ml. In the presence of the optimal dose of 100 U rIL-4/ml, PBMCs from five donors secreted a mean +/- SEM of 37 +/- 8 ng IgE/ml and 66 +/- 25 ng IgG4/ml. In kinetic studies, no IgG4 or IgE secretion was detected during the first 5 days of culture, and approximately 50% of the IgG4 and IgE secreted by day 15 was detected in supernatants on day 7. Cycloheximide, actinomycin-D, and mytomycin-C completely inhibited the rIL-4-induced IgG4 and IgE secretion, indicating that de novo protein, RNA, and DNA synthesis was required. As shown by Percoll buoyant density centrifugation, rIL-4 induced B cells in the high-density fraction to secrete IgG4 and IgE, whereas it inhibited spontaneous IgG4 secretion by low-density B cells. Interferon-gamma inhibited IL-4-induced IgG4 and IgE secretion. The data demonstrate that IL-4 induces small, dense, peripheral blood B cells to secrete not only IgE but also IgG4, which parallells the IL-4-induced IgE and IgG1 secretion by murine B cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulatory effect of recombinant interleukin (IL)3 and IL4 on cytokine gene expression of bone marrow and peripheral blood mononuclear cells

This study shows that both recombinant human interleukin (rhIL)3 and rhIL4 induced proliferation in bone marrow (BM) cells of myelogenous leukemia patients in a manner similar to that reported using normal BM cells. However, we additionally found that these cytokines also influenced expression of other cytokines. Namely, using a reproducible dot blot hybridization technique we observed on the one hand that BM cells were capable of constitutively expressing low levels of cytokine mRNA coding for IL3, IL4, granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte (G)-CSF and IL 1 beta, and on the other hand that in normal peripheral blood mononuclear cells rhIL4 inhibited mRNA expression coding for GM-CSF, G-CSF, IL3 and IL 1 beta, while IL4 mRNA and 28S rRNA was not affected. In contrast, rhIL3 marginally enhanced mRNA coding for IL3, GM-CSF, G-CSF and IL 1 beta and counteracted the inhibitory effect of IL4. In long-term cultures rhIL3 and rhIL4 had no significant effect on spontaneous cytokine gene expression of myelogenous leukemia-derived peripheral blood or BM cells, but made these cells more sensitive for subsequent stimulation with different polyclonal stimuli. Thus, IL3 and IL4 already modulate cytokine gene expression during the initiation of cell culture and differentiate BM cells into populations of cells which are capable of responding with an enhanced cytokine gene expression after polyclonal stimulation.

Purification and characterization of recombinant human interleukin 4. Biological activities, receptor binding and the generation of monoclonal antibodies

A synthetic gene coding for human interleukin 4 (IL-4) was cloned and expressed in Saccharomyces cerevisiae (baker's yeast) as a C-terminal fusion protein with the yeast prepro alpha-mating factor sequence, resulting in secretion of mature IL-4 into the culture medium (0.6-0.8 micrograms/ml). A protocol was developed for purification of this protein. Crude cell-free conditioned medium was passed over a concanavalin A-Sepharose affinity column; bound proteins were eluted and further purified by S-Sepharose Fast Flow cation exchange and C18 reverse-phase h.p.l.c. Highly purified IL-4 was obtained by this method (0.3-0.4 mg per litre of culture) with a recovery of 51%. Thermospray liquid chromatography-mass spectrometry showed the C-terminal N-glycosylation site to be largely unmodified, and also showed that the N-terminus of the purified recombinant IL-4 (rIL-4) was authentic. Thiol titration revealed no free cysteine residues, implying that there are three disulphide groups, the positions of which remain to be determined. We have characterized the biological activities of the purified rIL-4. This material is active in B-cell co-stimulator assays, T-cell proliferation assays and in the induction of cell-surface expression of CD23 (the low-affinity receptor for IgE) on tonsillar B-cells. Half-maximal biological activity of the rIL-4 was achieved at a concentration of 120 pM. We have radioiodinated rIL-4 without loss of biological activity and performed equilibrium binding studies on Raji cells, a human B-cell line. The 125I-rIL-4 bound specifically to a single class of binding studies on Raji cells, a human B-cell line. The 125I-rIL-4 bound specifically to a single class of binding site with high affinity (Kd = 100 pM) and revealed 1100 receptors per cell. Receptor-ligand cross-linking studies demonstrated a single cell-surface receptor with an apparent molecular mass of 124 kDa. Two monoclonal antibodies have been raised to the human rIL-4, one of which blocks both the biological activity of rIL-4 and binding to its receptor.