The effect of disodium cromoglycate (DSCG) on in vitro proliferation of CD4+, CD8+, and CD19+ cell populations derived from allergic and healthy donors

The effect of disodium cromoglycate (DSCG) on in vitro proliferation of CD4⁺ and CD8⁺ T cells and CD19⁺ B cells, positively selected by immunomagnetic separation, was investigated. The cells were obtained from allergic patients with moderate serum IgE levels and mild to moderate atopic dermatitis, and healthy controls. The different cell subfractions were stimulated with mitogens or specific allergens, as well as cell supernatants from the lymphoblastoid B- (RPMI 8866) and T-hybridoma (166 A₂) cell lines. Proliferative responses of T- and B-cell subsets stimulated with mitogens together with recombinant interleukin-2 (rIL-2) or accessory cells (AC) could be inhibited by DSCG. In allergic individuals, significant allergen-specific stimulation could be observed in the CD8-depleted peripheral blood mononuclear cell (PBMC) fractions. Isolated CD4⁺ T cells, without AC or IL-2, could also be stimulated with specific allergen, but the responses were rather low. DSCG inhibited, concentration dependently, all allergen-induced responses. Interestingly, only atopic derived CD4⁺ and CD8⁺ T cells were stimulated by soluble low-affinity IgE receptor (Fc?RII/sCD23) and IgE binding factor (IgEBF), including IgE enhancing factor, present in culture supernatants from RPMI 8866 and 166 A₂, respectively. These responses were also inhibited by DSCG. This was in contrast to the amplifying effect of DSCG on spontaneously proliferating RPMI 8866 and 166 A₂ cells, cultured in fresh cRPMI 1640 medium without sCD23 and IgE enhancing factor. Our results show that DSCG delivers an inhibitory signal or signals to PBMC subpopulations expressing Fc?RII/sCD23, either upregulated by phytohemagglutinin in normal and atopic cells, or by allergens or sCD23 in atopic cells. The findings suggest that sCD23 in supernatants or in serum may reverse the general inhibitory mode of DSCG.     

Regulation of Human Cytotoxic T Lymphocytes Development by the Synergistic Effect of IL-7 and sCD23

The present study was undertaken to investigate the interaction of IL-7 and sCD23 on human peripheral blood T cell activation and CTL differentiation. Purified T lymphocytes were stimulated with mitogen plus IL-2 and subcultured for 7 days with IL-7 and/or sCD23. The combination of IL-7 and sCD23 synergistically enhanced the proliferation of both CD4⁺and CD8⁺T cells. CD8⁺T cells, however, were usually more responsive to IL-7 and sCD23. This synergy was observed on both subsets of T cells. Furthermore, these cytokines synergistically augment the CTL activity of CD8⁺T cells in both mitogen- and antigen-activated T cells. MAbs anti-IL-2 or anti-IL-2R (CD25) and anti-IL-12 had no effect on T cell proliferation and CD8⁺cytotoxic activity induced by IL-7 and sCD23. We analyzed the effect on IFN-γ induction by CD8⁺T cells and found that IL-7 alone was incapable of inducing detectable levels of IFN-γ production, but together with sCD23 it enhanced the production of IFN-γ. We also found that IFN-γ was not required for enhanced CTL activity of CD8⁺T cells, because rabbit anti-IFN-γ did not block the synergistic effects of either cytokine. The data demonstrate that the synergistic stimulatory activity of IL-7 and sCD23 may be of significance in the human CTL development and provide an alternative mechanism of stimulating T cells for use in immunotherapy.     

CD23 expression on B-lymphocytes and its modulation by cytokines in allergic patients

The aim of this study was to assess the expression of CD23 on peripheral blood B-cells. and its in vitro modulation by recombinant human interferon-γ (IFN-γ) in phytohaem-agglutinin- (PHA) or recombinant human interleukin-4 (IL-4)-stimulaled cultures in atopic patients with Dermatophagoides pteromyssinus hyprrsensitivity and in healthy non-atopic subjects. Atopic patients with asthma not receiving allergen-specific immunotherapy (n= 21) were studied and further compared with a group of atopic subjects with asthma under allergen-specific immunotherapy (n = 21). They were age-(± 5 yr) and sex-matched. The results were also compared with those obtained in the non-atopic group (n= 11).CD23 expression on B-lymphocytes and its modulation were analysed by flow cytometry using conjugated monoclonal antibodies with a double immunofluorescence method. Atopic patients had an increase in the percentage of B-cells expressing CD23 in peripheral blood. Phytohaemagglutinin and IL-4 induced a rise in the percentage of CD23-positive B-cells in both atopic groups and non-atopic subjects. Phytohaemagglutinin provoked an increase in the intensity of CD23 expression on B-cells from stimulated cultures in all groups, while IL-4 only produced a significant increase in atopic patients. The presence of IFN-γ decreased the CD23 expression on B-cells in PH A-stimulated culture of atopic patients, whereas it caused an increase in CD23 expression in the non-atopic group. Furthermore, the presence of IFN-γ in IL-4-stimulatcd cultures induced a decrease in CD23 expression on B-cells in all cases. These results indicate a difference between atopic and non-alopic donors in their responses to IL-4 and IFN-γ. On the other hand, allergen-specific immunotherapy did not induce any shift in the expression and modulation of this receptor.     

Allergen-induced CD30 expression on T cells of atopic asthmatics

Background The importance of TH₂-type T cell cytokines in atopic disease is widely accepted. CD30, a member of the TNF/NGF receptor superfamily, is expressed on a proportion of activated CD45RO⁺ T cells and has been proposed as a marker for TH₂ phenotype. CD30 ligand-CD30 interaction has been shown to positively influence development of the TH₂ phenotype, and serum levels of soluble CD30 (sCD30) have been used as prognostic markers in HIV, SLE, Epstein-Barr Virus infection and Hodgkin's Lymphoma but not as yet in allergic disease. Objectives To establish if serum levels of sCD30 are elevated in atopic asthma and determine whether allergen-induced proliferation/activation of PBMCs from atopic asthmatics promotes CD30 expression on CD4⁺ T lymphocytes. Further, to determine if expression of CD30 and sCD30 correlate with disease severity. Methods Eighteen atopic asthmatics were each assigned a symptomatic disease score based on symptoms and bronchodilator rescue usage. Serum sCD30 was measured in peripheral blood by ELISA. PBMCs from atopic asthmatics were analysed with flow cytometry to obtain the proportions of CD⁴ T cells expressing CD45RO and CD30. The cells were then cultured for 10 days with IL-2 with or without house dust mite antigen. A proliferation index was recorded and expression of CD30 and CD45RO retested. As a control, stimulation with PHA was used. Results with patients’ PBMCs were compared with results of a parallel analysis of PBMCs from non-atopic healthy controls. Results Serum sCD30 was elevated in the 18 atopic asthmatics compared with a group of normal subjects but levels did not correlate with symptomatic disease activity. CD4CD45RO expression was low (14%) in atopic asthmatic peripheral blood but increased to 41% after 10 days culture with allergen. The CD4:CD8 ratio increased after Der p stimulation. A significant rise in the percentage of CD4⁴ T cells expressing surface CD30 (29%) was seen along with increased mean fluorescence intensity. Both these results correlated with symptomatic disease severity score. Non-specific PHA stimulation failed to significantly affect CD30 expression. Conclusions There is a specific response to allergen in atopic asthma which causes significant increases in CD30 expression. This may correlate with disease severity.     

Soluble CD40 ligand induces expression of CD25 and CD23 in resting human tonsillar B lymphocytes

In this report, we describe the dose-dependent increase in both CD25 and CD23 levels on resting human B cells in response to CD40 ligation, as mediated by soluble CD40 ligand (sCD40L) or anti-CD40 antibody. In combination with interleukin (IL)-4, sCD40L had limited additive effects on CD25 expression, but significantly enhanced CD23 expression on tonsillar B cells. Interferon-γ (IFN-γ) exerted no inhibitory effect upon increases in CD25 or CD23 driven by CD40 ligation with sCD40L or anti-CD40 antibody. These data suggest that the induction of CD25 and CD23 genes by IL-4 is mediated, at least in part, by an IFN-γ-sensitive component, whereas gene activation driven via CD40 ligation involves signaling pathways which are not sensitive to IFN-γ.     

Soluble CD21 induces activation and differentiation of human monocytes through binding to membrane CD23

Interactions between CD23, the low-affinity receptor for IgE, and CD21, the C3d/EBV receptor, modulate several intracellular events in lymphocytes. A soluble form of CD21 (sCD21) corresponding to the extracellular domain of the receptor circulates in normal plasma. We now demonstrate that purified sCD21 acts as a functional ligand for CD23-expressing monocytes. Soluble CD21 induced an increase in intracellular cGMP levels and the production of IL-6 and TNF-α in IL-4-pretreated monocytes induced to express CD23 but not in unstimulated CD23⁻ monocytes. The accumulation of cGMP and the production of TNF-α were inhibited by N^G-monomethyl-L -arginine (L -NMMA), indicating that sCD21 activates the L -arginine pathway of NO production. We demonstrated that sCD21 activates NO synthase (NOS) since it was found to enhance the conversion of L -arginine into L -citrulline and induce the intracellular expression of inducible NOS in CD23⁺ monocytes. In addition, sCD21 was shown to up-regulate the expression of HLA-DR and CD40 and decrease that of CD14 on cultured CD23⁺ monocytes. Thus, in a fashion similar to IgE complexes, sCD21 is able to efficiently trigger CD23 signaling pathways, inducing the release of pro-inflammatory mediators by human monocytes. Soluble CD21 up-regulates the expression of molecules involved in antigen presentation, further suggesting a potential immunoregulatory function for the soluble molecule.     

Spontaneous CD30 mRNA expression in peripheral blood mononuclear cells from atopic patients with high IgE serum levels

CD30 is a surface molecule which can be expressed by normal B and T lymphocytes. Our study focused on the CD30 expression and release compared with IL-4 expression as well as CD23-α/β in peripheral blood mononuclear cells (PBMC) from atopic subjects and controls. Data showed a lack of CD30 mRNA expression in the PBMC of control subjects, while it was significantly expressed in those of 6/11 atopic patients. No substantial amounts of spontaneous soluble CD30 (sCD30) could be detected by ELISA in both atopic and control groups. Interestingly, CD30 mRNA expression in PBMC of allergic patients was positively correlated with IgE serum levels (r = 0·79, P = 0·003). Studies on purified B cells showed that CD30 was expressed mainly in CD19⁺B cells of allergic patients. These data suggest highly a potential functional significance of the CD30 molecule in IgE response during allergic diseases.     

Opposite role for interleukin-4 and interferon-γ on CD30 and lymphocyte activation gene-3 (LAG-3) expression by activated naive T cells

Polarized human type 1 and type 2 T helper cells not only produce different sets of cytokines, but they also preferentially express certain activation markers, such as lymphocyte activation gene-3 (LAG-3) and CD30, respectively. In this study we have examined the LAG-3 and CD30 expression in relation to the lineage commitment of human naive CD4⁺ T cells, as assessed at the single-cell level of committed T cells. Purified CD45RA⁺ umbilical cord blood T lymphocytes were activated with phytohemagglutinin and interleukin (IL)-2 in the absence or presence of interleukin IL-4 or IL-12 and assessed for CD30 and LAG-3 expression, as well as for intracellular cytokine synthesis. Significant numbers of CD30⁺ cells were only found in CD4⁺ and CD8⁺ T lymphocytes of cultures primed with IL-4, which developed into cells able to produce IL-4 and IL-13 in addition to interferon (IFN)-γ. By contrast, LAG-3 expression was strongly up-regulated in CD4⁺ and CD8⁺ T cells from cultures primed with IL-12, which developed into high numbers of IFN-γ producers. The addition of a neutralizing anti-IFN-γ antibody to IL-12-primed CD4⁺ T cell cultures virtually abolished the development of LAG-3-expressing CD4⁺ T cells. Taken together, these data suggest that CD30 expression is dependent on the presence of IL-4, whereas LAG-3 expression is dependent on the production of IFN-γ during the lineage commitment of human naive T cells.     

Soluble CD14 acts as a negative regulator of human T cell activation and function

T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4⁺CD8⁻, CD4⁻CD8⁺ and CD4⁺CD8⁺ T cell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-γ and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IκB-α. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3⁺ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.     

Expression of low-affinity receptor for IgE (Fc epsilon RII, CD23) and IgE-BF (soluble CD23) release by lymphoblastoid B-cell line RPMI-8866 and human peripheral lymphocytes of normal and atopic donors.

The low-affinity receptor for IgE (CD23) as well as the soluble IgE-binding factors (IgE-BF, sCD23) are important factors in IgE antibody regulation. The CD23 expression and the concomitant release of CD23 were analysed from the lymphoblastoid B-cell line RPMI-8866 and from peripheral blood lymphocytes (PBL) of healthy volunteers as well as atopic patients. CD23 expression and sCD23 release of RPMI-8866 cells were dependent on the stage of culture. While CD23 expression decreased with increasing time of culture (Day 1-3), the sCD23 release was enhanced during the culture period. Cytokines such as IL-4, IL-2, TNF alpha and IFN-gamma exerted various effects on the target cells depending on the culture period. CD23 expression on normal lymphocytes was lower compared with the expression on atopic cells. Lymphokines (IL-2, IL-4) as well as mitogens (PHA, Con A) enhanced CD23 expression and IgE-BF (sCD23) release. The degree of enhancement was always higher with atopic cells compared with the results obtained with cells of normal donors.     

Schistosoma-specific helper T cell clones from subjects resistant to infection by Schistosoma mansoni are Th0/2

Although T helper cells play a critical role in human immunity against schistosomes, the properties of the T lymphocytes that govern resistance and pathogenesis in human schistosomiasis are still poorly defined. This work addresses the question as to whether human resistance to Schistosoma mansoni is associated with a particular T helper subset. Twenty-eight CD3⁺, CD4⁺, CD8^? parasite-specific T cell clones were isolated from three adults with high degree of resistance to infection by S. mansoni. The lymphokine secretion profiles of these clones were determined and compared to those of 21 CD3⁺, CD4⁺, CD8^? clones with unknown specificity, established from these same subjects in the same cloning experiment. Almost all parasite-specific clones produced interleukin (IL)-4 and interferon (IFN)-γ in large amounts. However, they generally produced more IL-4 than IFN-γ; variations in IL-4/IFN-γ ratios were accounted for by differences in IFN-γ production since IL-4 levels were comparable for the clones from the three subjects. T cell clones of unknown specificity produced significantly less IL-4 and more IFN-γ than parasite-specific T cell clones. Most clones produced IL-2, and IL-2 production did not differ between the two types of clones. Parasite-specific T cell clones from the resistant subjects were compared to specific T cell clones from a sensitized adult from a nonendemic area: T cell clones from this latter subject were the highest IFN-γ and the lowest IL-4 producers, compared to those of resistant subjects. Thus, parasite-specific T cell clones isolated from adults resistant to S. mansoni belong to the Th0 subset and produced more IL-4 than IFN-γ (Th0/2), whereas clones of a sensitized adult from a nonendemic area are also Th0, but produce more IFN-γ than IL-4 (Th0/1). These results support previous conclusions on the role of IgE in protection against schistosomes in humans, and may indicate that IFN-γ is required for full protection.     

CD83+ B cells alleviate uveitis through inhibiting DCs by sCD83

Soluble CD83 (sCD83) exerts immunosuppressive functions in many autoimmune diseases, including experimental autoimmune uveitis (EAU), but the cells and mechanisms involved are unclear. This study showed that CD83⁺ B cells were the main sources of sCD83. They alleviated the symptoms of EAU and decreased the percentage of T cells and DCs in the eyes and lymph nodes. These CD83⁺ B cells decreased IL-1β, IL-18 and IFN-γ secretion by DCs through sCD83. sCD83 interacted with GTPase Ras-related protein (Rab1a) in DCs to promote Rab1a accumulation in autolysosomes and inhibit mTORC1 phosphorylation and NLRP3 expression. Hence, CD83⁺ B cells play a regulatory role in EAU by secreting sCD83. The lack of regulation of CD83⁺ B cells might be an important factor leading to hyperimmune activation in patients with autoimmune uveitis. CD83⁺ B cells suppress activated DCs in uveitis, indicating the potential therapeutic role of CD83⁺ B cells in uveitis.     

Effect of an asthmatic attack on CD23 and CD21 expression on lymphocytes from allergic children during the allergen season

Background: The overproduction of IgE antibodies by atopic individuals in response to inhaled aeroallergen, forms the basis of an allergic disease. Furthermore, the exposure to allergen might trigger the symptom exacerbation. Objective: In children with bronchial asthma, the possible effects of seasonal, natural exposure to allergen on the expression of CD21 and CD23 antigens on B lymphocytes, and on the expression of HLA-DR, CD45RA and CD45RO on CD4⁺ T cells were investigated. Methods: Heparinized blood samples were obtained from 15 children with bronchial asthma allergic to Dermcttophagoides pteronyssimis (Der p) at the time of an acute asthmatic attack and 2–4 weeks after the attack when the peak expiratory flow (PEF) was stabilized. The samples were analysed on a flow cytometer after the three-colour immunofluorescence staining had been performed. Results: The increased proportion of B cells expressing CD23 antigen was found at the time of attack rather than after stabilization. Serum levels of total and Der p-specific IgE increased 2–4 weeks after the asthmatic attack. This increase was accompanied by a further increase in the expression of CD23 antigen on CD21^?B lymphocytes. In 10 out of 15 tested children, we found CD23 expressed on CD4⁺ HLA-DR⁺ T cells during the asthmatic attack. No significant difference was found in the expression of CD45RA and CD45RO antigens. Conclusion: Since we have previously demonstrated the increased percentage of CD23 on CD21^? B cells in allergic children as compared with controls, we speculate that natural exposure to the allergen which caused the increase in total and specific IgE levels might be related to the increased expression of CD23 on CD21^? B cells     

IgE secretion is attenuated by an inhibitor of proteolytic processing of CD23 (FcεRII)

CD23, the low-affinity IgE receptor, is up-regulated on interleukin (IL)-4-stimulated B cells and monocytes, with a concomitant increase in the release of soluble fragments of CD23 (sCD23) into the medium by proteolytic processing of the surface-bound intact CD23. The effect of inhibition of the processing of CD23 on IgE production in human and mouse cells and in a mouse model in vivo was evaluated. CD23 processing to sCD23 from RPMI 8866 (a human Epstein-Barr virus-transformed B cell line) cell membranes was inhibited by a broad-spectrum matrix-metalloprotease inhibitor, batimastat, with an IC₅₀ of 0.15 μM. Batimastat also inhibited CD23 processing in whole RPMI 8866 cells as well as in IL-4-stimulated purified human monocytes with similar IC₅₀. Batimastat inhibited IgE production from IL-4/anti-CD40-stimulated human tonsil B cells as well as mouse splenic B cells in a manner consistent with inhibition of CD23 processing. Release of soluble fragments of CD23 in the cell supernatants of tonsil B cells was inhibited over the concentration range of 1–10 μM batimastat and intact cell surface CD23 was increased on mouse splenic B cells in the presence of these concentrations of batimastat. IgE production of IL-4-stimulated human peripheral blood mononuclear cells was also blocked by 1–10 μM batimastat, again with comparable inhibition of sCD23 release over the same concentration range. Finally, in a mouse model of IgE production, batimastat inhibited IgE production in response to ovalbumin challenge as determined by serum IgE levels. Taken together, the data support a role of CD23 in IgE production and point to CD23 processing to sCD23 as a therapeutically relevant control point in the regulation of IgE synthesis.     

Interleukin-12 but not interferon-γ production correlates with induction of T helper type-1 phenotype in murine candidiasis

By means of polymerase chain reaction-assisted mRNA amplification, we have monitored message levels of interleukin (IL)-12 in splenic macrophages and of interferon-γ (IFN-γ), IL-4, and IL-10 in CD4⁺ and CD8⁺ T cells using Candida albicans/host combinations that result either in a T helper type-1 (Th1)-associated self-limiting infection (“healer mice”) or in a Th2-associated progressive disease (“nonhealer mice”). The timing and pattern of message detection did not differ qualitatively by the expression of IFN-γ or IL-10 mRNA in CD4⁺ and CD8⁺ cells from healer (i.e. PCA-2 into CD2F1) vs. nonhealer (i.e. CA-6 into CD2F1 or PCA-2 into DBA/2) mice. In contrast, IL-4 mRNA was uniquely expressed by CD4⁺ cells from nonhealer animals. IL-12p40 was readily detected in macrophages from healer mice but was detected only early in infection in mice with progressive disease. Cytokine levels were measured in sera, and antigen-driven cytokine production by CD4⁺ and CD8⁺ cells was assessed in vitro, while IFN-γ-producing cells were enumerated in CD4^? CD8^? cell fractions. Overall, our results showed that (i) antigen-specific secretion of IFN-γ protein in vitro by CD4⁺ cells occurred only in healing infection; (ii) IL-4- and IL-10-producing CD4⁺ cells would expand in nonhealer mice in the face of high levels of circulating IFN-γ, likely released by CD4^? CD8^? lymphocytes; (iii) a finely regulated IFN-γ production correlated in the healer mice with IL-12 mRNA detection, and IL-12 was required in vitro for yeast-induced development of IFN-γ-producing CD4⁺ cells. Although the mutually exclusive production of IL-4/IL-10 and IFN-γ by early CD4⁺ cells may be the major discriminative factor of cure and noncure responses in candidiasis, IL-12 rather than IFN-γ production may be an indicator of Th1 differentiation.     

Allergen-induced CD23 on CD4+ T lymphocytes and CD21 on B lymphocytes in Patients with allergic asthma: Evidence and regulation

Interaction of CD4⁺ T cells and B cells is necessary for IgE production. It has been recently demonstrated that cell surface antigen CD21 is a ligand for CD23 (Fc?RII) and that the pairing of these molecules may participate in the control of IgE production. In this study we investigated the effect of the Dermatophagoides pteronyssinus (Dpt) allergen and recombinant interleukin(rIL)-4 on the expression of CD21 and CD23 on T and B cells of asthmatic patients allergic to Dpt and of healthy controls. Peripheral blood mononuclear cells (PBMC) were incubated alone or with Dpt allergen (100 biological units/ml) and/or rIL-4 (100 U/ml) for up to 7 days. The flow-cytometric analysis of double-fluorescence staining revealed that Dpt allergen and/or rIL-4 induced CD23 on CD4⁺ T lymphocytes only in allergic patients. The allergen-induced CD23 on T cells is de novo synthesized antigen since no induction of CD23 on T cells was observed in cultures with 0.4 μg/ml actinomycin D. Moreover, 100 U/ml of interferon-γ inhibited the induction of CD23 on CD4⁺ T cells. T cells obtained from healthy donors did not express CD23 or CD21 antigen upon incubation with allergen and/or rIL-4. Although rIL-4 also induced CD23 in controls, the expression was only observed on CD20⁺ cells. The allergen alone induced a significant elevation of the mean fluorescence intensity of both CD21 and CD23 only in allergic in dividuals. When the cell proliferation was analyzed, a slightly increased stimulation index upon cultivation of PBMC was obtained from non-allergic donors as well, but less than in allergic patients. The co-expression of major histocompability complex class II molecules and CD23 on CD4⁺ T lymphocytes in allergic patients, as assessed by the three-color immunofluorescence analysis, indicates that these cells were activated. We conclude that CD4⁺ T lymphocytes possess a unique capability to express CD23 upon exposure to allergen. Moreover, the allergen-mediated induction of CD23 on T cells observed only in allergic patients may be the reason for the increase of IgE production. This would not occur in non-allergic individuals as there is no CD23 expression on T cells.     

The relative contribution of IL-4 and IL-13 to human IgE synthesis induced by activated CD4 or CD8 T cells

The relative contribution of IL-4 and IL-13 to the regulation of IgE synthesis has remained relatively poorly characterized, partially because of lack of suitable animal models. We have studied the roles of IL-4 and IL-13 in human IgE synthesis induced by supernatants derived from activated CD4⁺⁺ or CD8⁺ T cell clones. Neutralizing anti–IL-4 and anti–IL-13 monoclonal antibodies (mAbs) inhibited IgE synthesis induced by anti-CD40 mAbs and supernatants from CD4⁺ T cells by an average 61% and 42%, respectively (n = 25). Recombinant IL-13 had additive effects on IL-4-induced IgE synthesis, but only when IL-4 was present at low concentrations. Accordingly, IL-4 was the dominant IgE synthesis–inducing cytokine derived from highly polarized T helper (TH)₂ cells. However, anti–IL-13 mAbs also significantly inhibited IgE synthesis induced by two of three supernatants derived from allergen-specific T_H2-like cell lines generated from the skin of patients with atopic dermatitis. Furthermore, anti–IL-13 mAbs almost completely inhibited IgE synthesis induced by supernatants from T_H1 cells or CD8⁺ T cell clones. Taken together, these data indicate that IL-13, in addition to IL-4, contributes to IgE synthesis induced by all T helper cell subsets, including allergen-specific T_H2 cells. Moreover, IL-13 appears to be the major IgE synthesis–inducing cytokine derived from T_H1 cells or CD8⁺ T cells. (J Allergy Clin Immunol 1997;100:792-801.)     

Secretion of the eosinophil-active cytokines interleukin-5, granulocyte/macrophage colonystimulating factor and interleukin-3 by bronchoalveolar lavage CD4+ and CD8+ T cell lines in atopics asthmatics,and atopic and nonatopic controls

Specific eosinophil accumulation and activation within the asthmatic bronchial mucosa are thought to occur at least partly through the actions of cytokines, including interleukin (IL)-5, IL-3 and granulocyte/macrophage colonystimulating factor (GM-CSF). Although mRNA encoding some of these cytokines has been demonstrated in bronchoalveolar lavage (BAL) fluid cells and bronchial biopsies from asthmatics, it has yet to be established whether these cells produce the translated products and whether expression is associated with CD4⁺ T helper or CD8⁺ cytotoxic T cells. We addressed this problem by raising polyclonal CD4⁺ and CD8⁺ T cell lines from the BAL fluid of six atopic asthmatics, five atopic non-asthmatics and seven non-atopic non-asthmatic controls. BAL fluid cells obtained at fiberoptic bronchoscopy were depleted of adherent cells, and then T lymphocytes expanded by stimulation with monoclonal anti-CD3 antibody and recombinant human IL-2. When lymphocytes had expanded to sufficient numbers, CD4⁺ and CD8⁺ cells were separated by positive selection with magnetic beads coated with anti-CD4 or anti-CD8 monoclonal antibodies and further expanded. Cytokine secretion by standardized cell numbers was measured by enzyme-linked immunosorbent assays. BAL CD4⁺ T cell lines from the asthmatics secreted significantly elevated quantities of both IL-5 and GM-CSF as compared with lines from the atopic and non-atopic controls (p = 0.023–0.003). In contrast, IL-3 secretion did not significantly differ between the groups. In some subjects, CD8⁺ T cell lines also secreted significant quantities of these cytokines and there was a trend for IL-5 secretion by these cells to be higher in asthmatics than non-atopic controls (p = 0.035). These data are consistent with the hypothesis that activated T lymphocytes from asthmatics, particularly of the CD4⁺ subset, are predisposed to release elevated quantities of cytokines relevant to the accumulation and activation of eosinophils.     

Circulating elevated levels of soluble CD23, interleukin-4, and CD20+CD23+ lymphocytes in atopic subjects with elevated serum IgE concentrations.

Circulating IgE protein levels, leukocyte counts, lymphocyte subsets, IL-4, and soluble CD23 levels were quantitated in 43 atopic and 19 nonatopic subjects. Mean values of IgE protein levels, total eosinophil counts, CD20+CD23+ cells (B cells with low-affinity IgE receptor), IL-4 and sCD23 levels were elevated in atopic patients compared with nonatopic controls. The results suggest that sCD23, IL-4, and CD20+CD23+ lymphocytes may play a role in the increased production of IgE in atopic subjects in a manner similar to that observed by other investigators in prior in vitro studies.