Antigen-specific versus total immunoglobulin synthesis: total IgE and IgG1, but not IgG2a levels predict murine antigen-specific responses

BACKGROUND

Induction of an effective antibody (Ab) response requires delivery of multiple signals to B cells. Cross-linking of the B cell antigen receptor (BCR), signaling through CD40 and CD80/86 and cytokine signals combine to induce class switching and expression of specific isotypes. These signals are principally derived from activated, antigen (Ag)-specific T cells. In contrast, IFNgamma, the only cytokine known to induce class switch to IgG2a, can be produced systemically by activated NK or NKT cells, suggesting that Ag-nonspecific signals may also regulate IgG2a production.

METHODS

Given the potential differences in regulation between IgE/IgG1 versus IgG2a, we immunized mice on day 0 with ovalbumin (OVA) in the presence of strong type-1- or type-2-immunity-inducing adjuvants and boosted mice 4 weeks later. Mice were bled during the primary immune response and after boost to assess primary and recall Ab responses.

RESULTS

Regardless of strain of mice used, phenotype (type 1 versus type 2 dominated) or nature of the immune response induced (primary versus recall), strong correlations between OVA-specific and total IgE and IgG1 were demonstrated. In contrast, a consistent lack of correlation between OVA-specific and total IgG2a levels was observed in all but BALB/c mice.

CONCLUSION

These data indicate that the increase in total levels of IgE/IgG1 isotypes is primarily a result of increased levels of OVA-specific Ab. In contrast, the lack of correlation between total and OVA-specific IgG2a suggests broader activation of IgG2a-producing B cells routinely occurs following exogenous Ag immunization.

Adenoid-derived TH2 cells reactive to allergen and recall antigen express CC chemokine receptor 4

BACKGROUND

Interrupting recruitment of allergen-specific T(H)2 cells to the airway is an attractive potential therapeutic strategy for allergic disease. CC chemokine receptor 4 (CCR4) is preferentially expressed on T(H)2 cells, and CCR4-expressing cells have been described at sites of allergic inflammation. However, whether selective recruitment of allergen-specific T(H)2 cells to the airways occurs through CCR4 or other chemokine receptors remains controversial.

OBJECTIVE

We investigated the expression of the T(H)2-associated chemokine receptors (CCR3, CCR4, and CCR8) by primary antigen-specific human airway T(H)2 cells.

METHODS

Children undergoing elective adenoidectomy were recruited, and their atopic status was determined. Adenoid cells were cultured with allergen or recall antigen. Flow cytometric analyses permitted identification of T(H) cells proliferating in response to antigen and characterization of chemokine receptor and cytokine expression.

RESULTS

An increased proportion of airway CD4(+) T cells proliferated to allergen in atopic children (n = 6, of which 4 were given diagnoses of asthma or rhinitis) compared with nonatopic children (P =.0004). These cells were 44.7% (32.6% to 50.0%) IL-4(+) and only 2.5% (0.6% to 3.3%) IFN-(gamma) and showed a greater than 5-fold upregulation of CCR4 expression to 54.0% (40.7% to 67.8%) after culture, whereas CCR3 was expressed on 9.7% (7.4% to 18.9%) of allergen-reactive cells and CCR8 on less than 1%. Interestingly, increased expansion of recall antigen-specific cells was also seen in atopic children, and these cells were also predominantly of a T(H)2 CCR4(+) phenotype.

CONCLUSION

We conclude that airway allergen-specific T(H)2 cells are CCR4(+), but in the atopic child CCR4 does not distinguish between recall antigen and allergen specificity.

Chemokines in autoimmune lacrimal gland disease in MRL/MpJ mice

PURPOSE

MRL/MpJ-fas+/fas+ (MRL/+) and MRL/MpJ-fas(lpr)/fas(lpr) (MRL/lpr) mice undergo spontaneous development of inflammation of the lacrimal and salivary glands, similar to that in the human disorder Sjögren's syndrome. Previous work has shown that these lesions appear to be largely T helper (Th)-2-driven, as evidenced by the substantially greater expression of IL-4 than interferon-gamma. The relative contributions of selected chemokines associated with Th1 and Th2 immune responses were assessed.

METHODS

Lacrimal glands from MRL/+ and MRL/lpr mice, at ages 1.5 through 9 months were evaluated by immunohistochemistry for the chemokines monocyte chemoattractant protein (MCP)-1 (also known as chemokine ligand [CCL]-2), MCP-5 (CCL12), thymus activation regulated chemokine (TARC; or CCL17), and macrophage-derived chemokine (MDC; or CCL22). Additional lacrimal glands were tested by real-time RT-PCR for chemokines MCP-1 and -5, which are associated with Th2 and Th1 responses, respectively.

RESULTS

By immunohistochemistry a significantly greater proportion of mononuclear inflammatory cells in the lacrimal gland lesions stained for MCP-1 (29%-48% depending on age) compared with MCP-5 (1%-3% depending on age) both in MRL/+ (mean difference 34.2%, P < 0.001) and MRL/lpr (mean difference 33.6%, P < 0.001) substrains. Real-time RT-PCR studies showed higher transcript levels of MCP-1 compared with MCP-5, in both MRL/+ (median difference, 37.3; P < 0.0001) and MRL/lpr (median difference, 77.1; P < 0.0001) mice. Relative transcripts of MCP-1 increased with age in both MRL/+ mice (P = 0.02) and MRL/lpr mice (P = 0.03). Staining for TARC was present on lacrimal gland ductular cells but not on the infiltrating lymphocytes, and staining for MDC was present on scattered individual cells throughout the lacrimal gland, but not on infiltrating lymphocytes.

CONCLUSIONS

The predominant expression of a Th2-associated chemokine in the lacrimal gland lesions in this murine model of Sjögren's syndrome may contribute to the predominantly Th2-type lymphoid infiltrate in these tissues.

Assessment of Be1 and Be2 cells in systemic lupus erythematosus indicates elevated interleukin-10 producing CD5+ B cells

Recent studies indicate that normal B cells can be primed to differentiate into two distinct cytokine-secreting effector subsets, Be1 and Be2. The aim of this study was to analyse, for the first time, Be1 and Be2 cells at the single cell level in SLE patients using the recently developed technique of flow cytometry for intracellular cytokines. Peripheral blood mononuclear cells (PBMC) from SLE patients and age- and sex-matched normal controls were cultured for 24 h in the presence or absence of phorbal myristate acetate and ionomycin (PMA/I) or lipopolysaccharide (LPS). The production of type I (IFN-gamma, IL-2) and type 2 (IL-4, IL-5, IL-6, IL-10, IL-13) cytokines by B cells (and IL-10 production by fractionated CD5+ and CD5- B cells) was investigated using an intracellular cytokine staining technique and flow cytometry. In the absence of PMA/I stimulation, the percentage of B cells from SLE patients was significantly lower than those of normal subjects and significantly more SLE B cells spontaneously produced IL-10 than controls. Moreover, CD5+ B cells from SLE patients were enriched for cells with signs of previous in vivo activation and for high levels of IL-10 production. A significant positive correlation was observed between the percentage of IL-10- and IL-6-producing PMA/I-stimulated B cells in SLE patients, but not in controls. There were no significant differences in the production of other cytokines by B cells of SLE patients and normal subjects. In conclusion, a general alteration of type 1 and type 2 cytokine production by B cells is not observed in SLE patients. The role of B cell cytokines in the pathogenesis of SLE appears to be exerted by elevated secretion of in vivo IL-10, which may play an important role in the immune dysregulation observed in SLE patients. Moreover, the cross regulation of IL-10 and IL-6 is disrupted in SLE patients.

Effect of the resection of the sciatic nerve on the Th1/Th2 balance in the synovia of the ankle joint of adjuvant arthritic rats

Inflamed synovia of the ankle joint after 2-4 weeks of adjuvant injection receives dense sensory innervation. To study the role of sensory nerves on the local inflammation, the relative expression of T helper 1 and 2 lymphocyte (Th1 and Th2) markers was investigated on both axotomized adjuvant arthritic (AA) rats, whose sciatic nerves were resected before adjuvant injection, and on sham-operated ones. Immunohistochemical expressions of CXC chemokine receptor 3 (CXCR3) and CC chemokine receptor 4 (CCR4) were examined and compared with those of Th1 cytokine (interferon-gamma, IFN-gamma), Th2 cytokine (interleukin-4, IL-4), and anti-T cell antibody (W3/25). Double-positive cells for IFN-gamma/CXCR3 and for IL-4/CCR4 were greater than 90% and greater than 95%, respectively. The reciprocal combinations, IL-4/CXCR3 and IFN-gamma/CCR4, however, yielded less than 10% and less than 5% of double-positive cells. CXCR3 and CCR4 thus appear to be available as markers for Th1/Th2 subsets in the synovia of AA rats. Using these markers, it became clear that the percentage of Th1 cells to total Th cells was higher than that of Th2 cells in axotomized AA rats at weeks 2-4, whereas in sham-operated AA rats, the percentage of Th1 cells to total Th cells was higher than that of Th2 cells at week 2 and the latter exceeded the former at week 4. Our observations strongly suggested the presence of the anti-inflammatory action of sensory nerves in rats with adjuvant arthritis.

IFN-gamma-independent effects of IL-12 during intestinal nematode infection

Expulsion of the gastrointestinal nematode Trichinella spiralis is associated with a pronounced mastocytosis mediated by a Th2-type response involving IL-4, IL-10, and IL-13. When exogenous rIL-12 was administered to T. spiralis-infected NIH mice, this resulted in significant suppression of intestinal mast cell responses, delayed worm expulsion, increased muscle larvae burdens, and a transient, but significant decrease in early Th2 cytokine secretion. rIL-12 treatment also altered chemokine expression in the jejunal mucosa. The effects of exogenous IL-12 administration were largely independent of IFN-gamma as shown by rIL-12 treatment of IFN-gamma knockout mice. Hence, IL-12 may play a significant biological role as a direct negative regulator of intestinal Th2 responses and may act to promote the survival of intestinal parasites in vivo also in the absence of IFN-gamma.

Activation of mast cells is essential for development of house dust mite Dermatophagoides farinae-induced allergic airway inflammation in mice

In this study, we demonstrate that Dermatophagoides farinae (Der f), a major source of airborne allergens, but not OVA, could rapidly activate mast cells in mice. This was indicated by an elevation of serum mouse mast cell protease 1, a mast cell-specific proteinase, as early as 30 min after intratracheal challenge. Administration of sodium cromoglycate (40 mg/kg, i.p., 1 h before Der f instillation), a mast cell stabilizer, not only suppressed acute mouse mast cell protease 1 production but also attenuated the allergic airway inflammation provoked by repetitive Der f challenge in mice (five times at 1-wk interval). Der f induced the expression of mRNA for TNF-alpha, IL-1beta, IL-4, IL-6, IL-9, and IL-13 in mastocytoma P815 cells and stimulated both P815 cells and bone marrow-derived mast cells to produce IL-4, IL-6, and TNF-alpha in a dose- and time-dependent manner. Cycloheximide as well as sodium cromoglycate blocked the Der f-induced IL-4 production, indicating a de novo protein synthesis process. Supernatants of Der f-stimulated mast cells chemoattracted monocytes and T lymphocytes; they up-regulated the expression of costimulatory B7 molecules, eotaxin, RANTES, monocyte chemoattractant protein 1, and IFN-inducible protein 10 mRNA of alveolar macrophages; they supported PHA-induced T cell proliferation; and they promoted Th2 cell development. Our data indicate that mast cells may be an important cell type during the initiation of Der f sensitization in the airway by modulating the function of alveolar macrophages and T cells.

Global gene expression profiles during acute pathogen-induced pulmonary inflammation reveal divergent roles for Th1 and Th2 responses in tissue repair

T helper 1 responses are typically proinflammatory, while Th2 responses have been considered regulatory. Interestingly, Th2 responses characterize a number of pulmonary diseases, many of which terminate in tissue remodeling and fibrosis. We developed a mouse model using Schistosoma mansoni eggs and cytokine-deficient mice to induce highly polarized Th1- or Th2-type inflammation in the lung. In this study, we examined the pathology and cytokine profiles in Th1- and Th2-polarized environments and used oligonucleotide microarray analysis to decipher the genes responsible for these effects. We further elaborated on the results using IL-10- and IL-13-deficient mice because these cytokines are believed to be the central regulators of Th2-associated pathology. We found that the Th1-polarized mice developed small granulomas with less fibrosis while expressing genes characteristic of tissue damage. Th2-polarized mice, in contrast, formed large granulomas with massive collagen deposition and up-regulated genes associated with wound healing, specifically, arginase, collagens, matrix metalloproteinases (MMPs), and tissue inhibitors of MMP. In addition, several members of the chitinase-like family were up-regulated in the lung following egg challenge. We also developed a method of defining the net collagen deposition using the expression profiles of several collagen, MMP, and tissue inhibitors of MMP genes. We found that Th1-polarized mice did not elaborate collagens or MMPs and therefore did not have a significant capacity for repair in this model. Thus, Th1-mediated inflammation is characterized by tissue damage, while Th2 directs wound healing and fibrosis.

Genetic reprogramming of primary human T cells reveals functional plasticity in Th cell differentiation

Activation of naive T cells through the TCR and cytokine signals directs their differentiation into effector or memory subsets with different cytokine profiles. Here, we tested the flexibility of human Th1 or Th2 differentiation by forced expression of transcription factors T-bet and GATA-3. Ectopic expression of T-bet and GATA-3 in freshly isolated human T(N) cells resulted in their differentiation to a Th1 and Th2 phenotype, respectively, in the absence of polarizing cytokines. Introduction of GATA-3 into lineage-committed Th1 cells induced the expression of Th2-specific cytokines (IL-4 and IL-5) and chemotactic receptors (CCR4, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). However, these cells partially maintained their Th1-specific profile (IFN-gamma and IL-12Rbeta2 expression). Conversely, expression of T-bet in lineage-committed Th2 cells caused a more profound switch to the Th1 phenotype, including the up-regulation of CXCR3 and down-regulation of CCR4 and CRTH2. Interestingly, similar to the naive T cell subset, central memory T cells were also largely programmed toward Th1 or Th2 effector cells upon expression of T-bet and GATA-3, respectively. However, expression of these transcription factors in effector memory T cells was much less influential on cytokine and chemokine receptor expression profiles. Our results reveal remarkable plasticity in the differentiation programs of human memory T cells. This flexibility is progressively diminished as cells mature from naive to effector T cells. These findings have important implications in understanding the molecular mechanisms of human T cell differentiation and for devising novel therapeutic strategies aimed at immunomodulation of skewed effector T cell responses.

Lipopolysaccharide-induced suppression of airway Th2 responses does not require IL-12 production by dendritic cells

The prevalence of atopic asthma, a Th2-dependent disease, is reaching epidemic proportions partly due to improved hygiene in industrialized countries. There is an inverse correlation between the level of environmental endotoxin exposure and the prevalence of atopic sensitization. As dendritic cells (DC) have been implicated in causing sensitization to inhaled Ag, we studied the effect of endotoxin on Th2 development induced by bone marrow DC in vitro and by intratracheal injection in vivo, with particular emphasis on the role played by the polarizing cytokine IL-12. Bone marrow-derived DC stimulated with Escherichia coli O26:B6 LPS produced IL-12p70 for a limited period of time, after which production became refractory to further stimulation with CD40 ligand, a phenomenon previously called "exhaustion." The level of IL-12 production of DC did not correlate with Th1 development, as exhausted OVA-pulsed DC were still capable of shifting the cytokine pattern of responding OVA-specific Th cells toward Th1 in vitro and in vivo. When mice were first immunized by intratracheal injection of OVA-DC and subsequently challenged with OVA aerosol, prior in vitro stimulation of DC with LPS reduced the development of airway eosinophilia and Th2 cytokine production. Most surprisingly, the capacity of LPS to reduce Th2-dependent eosinophilic airway inflammation was IL-12-independent altogether, as IL-12p40 knockout DC had a similar reduced capacity to prime for Th2 responses. These results suggest that LPS reduces sensitization to inhaled Ag by reducing DC-driven Th2 development, but that IL-12 is not necessary for this effect.

Identification of novel IL-4/Stat6-regulated genes in T lymphocytes

IL-4, primarily produced by T cells, mast cells, and basophiles, is a cytokine which has pleiotropic effects on the immune system. IL-4 induces T cells to differentiate to Th2 cells and activated B lymphocytes to proliferate and to synthesize IgE and IgG1. IL-4 is particularly important for the development and perpetuation of asthma and allergy. Stat6 is the protein activated by signal transduction through the IL-4R, and studies with knockout mice demonstrate that Stat6 is critical for a number of IL-4-mediated functions including Th2 development and production of IgE. In the present study, novel IL-4- and Stat6-regulated genes were discovered by using Stat6(-/-) mice and Affymetrix oligonucleotide arrays. Genes regulated by IL-4 were identified by comparing the gene expression profile of the wild-type T cells induced to polarize to the Th2 direction (CD3/CD28 activation + IL-4) to gene expression profile of the cells induced to proliferate (CD3/CD28 activation alone). Stat6-regulated genes were identified by comparing the cells isolated from the wild-type and Stat6(-/-) mice; in this experiment the cells were induced to differentiate to the Th2 direction (CD3/CD28 activation + IL-4). Our study demonstrates that a number a novel genes are regulated by IL-4 through Stat6-dependent and -independent pathways. Moreover, elucidation of kinetics of gene expression at early stages of cell differentiation reveals several genes regulated rapidly during the process, suggesting their importance for the differentiation process.

Induction of macrophage insulin-like growth factor-I expression by the Th2 cytokines IL-4 and IL-13

Macrophage-derived insulin-like growth factor-I (IGF-I) has long been implicated in the pathogenesis of the interstitial lung disease, idiopathic pulmonary fibrosis, in part, by its ability to 1) stimulate the proliferation and survival of fibroblasts and myofibroblasts and 2) promote collagen matrix synthesis by these cells. However, little is known about the mechanisms that stimulate the expression of IGF-I by macrophages. Previous studies have shown that the development of pulmonary fibrosis is accompanied by enhanced expression of Th2-profile cytokines, especially IL-4, and diminished expression of Th1 cytokines, including IFN-gamma. In addition, in vitro studies have shown that IFN-gamma down-regulates the expression of IGF-I. Thus, the paucity of IFN-gamma in the fibrotic lung may favor increased growth factor production by allowing Th2 cytokines to predominate. In view of these findings, we investigated the hypothesis that Th2 cytokines stimulate the expression of IGF-I by macrophages. Incubation with IL-4 or IL-13 led to concentration- and time-dependent increases in the expression of IGF-I mRNA and the secretion of IGF-I protein by mouse macrophages as a consequence of increased transcription of IGF-I pre-mRNA. Exposure of macrophages to IL-4 in the presence of IFN-gamma inhibited the increase in the expression of IGF-I. Studies using STAT6-deficient macrophages indicated that the increase in IGF-I expression was dependent on STAT6. In addition, the down-regulation of IGF-I expression by IFN-gamma was absent in STAT1-deficient macrophages. Collectively, these findings define a homeostatic mechanism in which Th2 cytokines promote, and Th1 cytokines inhibit, the expression of IGF-I by macrophages.

Cutting edge: cyclooxygenase-2 activation suppresses Th1 polarization in response to Helicobacter pylori

Helicobacter pylori infection causes a Th1-driven mucosal immune response. Cyclooxygenase (COX)-2 is up-regulated in lamina propria mononuclear cells in H. pylori gastritis. Because COX-2 can modulate Th1/Th2 balance, we determined whether H. pylori activates COX-2 in human PBMCs, and the effect on cytokine and proliferative responses. There was significant up-regulation of COX-2 mRNA and PGE(2) release in response to H. pylori preparations. Addition of COX-2 inhibitors or an anti-PGE(2) Ab resulted in a marked increase in H. pylori-stimulated IL-12 and IFN-gamma production, and a decrease in IL-10 levels. Addition of PGE(2) or cAMP, the second messenger activated by PGE(2), had the opposite effect. Similarly, stimulated cell proliferation was increased by COX-2 inhibitors or anti-PGE(2) Ab, and was decreased by PGE(2). Our findings indicate that COX-2 has an immunosuppressive role in H. pylori gastritis, which may protect the mucosa from severe injury, but may also contribute to the persistence of the infection.

Burn injury promotes antigen-driven Th2-type responses in vivo

Severe injury induces detrimental changes in immune function, often leaving the host highly susceptible to developing life-threatening opportunistic infections. Advances in our understanding of how injury influences host immune responses suggest that injury causes a phenotypic imbalance in the regulation of Th1- and Th2-type immune responses. We report in this study, using a TCR transgenic CD4(+) T cell adoptive transfer approach, that injury skews T cell responses toward increased Th2-type reactivity in vivo without substantially limiting Ag-driven CD4(+) T cell expansion. The increased Th2-type response did not occur unless injured mice were immunized with specific Ag, suggesting that the phenotypic switch is Ag dependent. These findings establish that severe injury induces fundamental changes in the induction of Ag-specific CD4(+) Th cell responses favoring the development of Th2-type immune reactivity in vivo.

Blockade of airway inflammation and hyperresponsiveness by HIV-TAT-dominant negative Ras

We have reported previously that HIV-TAT-dominant negative (dn) Ras inhibits eosinophil adhesion to ICAM-1 after activation by IL-5 and eotaxin. In this study, we evaluated the role of Ras in Ag-induced airway inflammation and hyperresponsiveness by i.p. administration into mice of dnRas, which was fused to an HIV-TAT protein transduction domain (TAT-dnRas). Uptake of TAT-dnRas (t(1/2) = 12 h) was demonstrated in leukocytes after i.p. administration. OVA-sensitization significantly increased eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid 24 h after final challenge. Treatment of animals with 3-10 mg/kg TAT-dnRas blocked the migration of eosinophils from 464 +/- 91 x 10(3)/ml to 288 +/- 79 x 10(3)/ml with 3 mg/kg of TAT-dnRas (p < 0.05), and further decreased to 116 +/- 63 x 10(3)/ml after 10 mg/kg TAT-dnRas (p < 0.01). Histological examination demonstrated that inflammatory cell infiltration (largely eosinophils and mononuclear cells) and mucin production around the airways caused by OVA were blocked by TAT-dnRas. OVA challenge also caused airway hyperresponsiveness to methacholine, which was dose dependently blocked by treatment with TAT-dnRas. TAT-dnRas also blocked Ag-induced IL-4 and IL-5, but not IFN-gamma, production in lung tissue. Intranasal administration of IL-5 caused eosinophil migration into the airway lumen, which was attenuated by pretreatment with TAT-dnRas. By contrast, TAT-green fluorescent protein or dnRas lacking the TAT protein transduction domain did not block airway inflammation, cytokine production, or airway hyperresponsiveness. We conclude that Ras mediates Th2 cytokine production, airway inflammation, and airway hyperresponsiveness in immune-sensitized mice.

Bisphenol A promotes IL-4 production by Th2 cells

BACKGROUND

It has been proposed that estrogen plays an important role in modulating the Th1/Th2 cytokine balance. From this viewpoint, chemicals with estrogenic responses were expected to possess similar immunoregulatory roles which have not been defined to date. To address this, we studied the effects of one of the estrogenic chemicals, bisphenol A (BPA), on the in vitro production of Th1 and Th2 cytokines.

METHODS

Mesenteric lymph node cells from Trichinella spiralis (Ts)-infected mice were incubated with serialfold dilutions of BPA under stimulation with Ts antigen. The Th2 cytokine production in the supernatant was determined by ELISA. The Th2 cytokine production by mesenteric lymph node cells from Ts-infected mice inoculated orally with BPA was compared with that of uninoculated mice infected with Ts.

RESULTS

The antigen-stimulated interleukin (IL)-4 production by Th2-dominant mesenteric lymph node cells from Ts-infected mice increased significantly by addition of 3 microM of BPA. The IL-5 production was not affected. The production of IL-4, but not that of IL-5, by splenocytes of Th2-skewed Leishmania major-infected BALB/c mice increased at concentrations of 3 and 10 microM of BPA. However, the interferon gamma production was not affected by BPA in Th1-skewed L. major-infected C57BL/6 mice. The production of IL-4 and IL-10, but not that of IL-13, markedly increased in Ts-infected mice inoculated orally with BPA.

CONCLUSIONS

We demonstrated that the IL-4 production was increased both in vitro and in vivo by treatment with BPA. This suggests that BPA might cause allergic diseases by stimulating the IL-4 production by Th2 cells.

Dissociation of NKT Stimulation, Cytokine Induction, and NK Activation In Vivo by the Use of Distinct TCR-Binding Ceramides

NKT and NK cells are important immune regulatory cells. The only efficient means to selectively stimulate NKT cells in vivo is alpha-galactosylceramide (alphaGalCer). However, alphaGalCer effectively stimulates and then diminishes the number of detectable NKT cells. It also exhibits a potent, indirect ability to activate NK cells. We have now discovered another ceramide compound, beta-galactosylceramide (betaGalCer) (C12), that efficiently diminishes the number of detectable mouse NKT cells in vivo without inducing significant cytokine expression or activation of NK cells. Binding studies using CD1d tetramers loaded with betaGalCer (C12) demonstrated significant but lower intensity binding to NKT cells when compared with alphaGalCer, but both ceramides were equally efficient in reducing the number of NKT cells. However, betaGalCer (C12), in contrast to alphaGalCer, failed to increase NK cell size, number, and cytolytic activity. Also in contrast to alphaGalCer, betaGalCer (C12) is a poor inducer of IFN-gamma, TNF-alpha, GM-CSF, and IL-4 gene expression. These qualitative differences in NKT perturbation/NK activation have important implications for delineating the unique in vivo roles of NKT vs NK cells. Thus, alphaGalCer (which triggers NKT cells and activates NK cells) efficiently increases the resistance to allogeneic bone marrow transplantation while betaGalCer (C12) (which triggers NKT cells but does not activate NK cells) fails to enhance bone marrow graft rejection. Our results show betaGalCer (C12) can effectively discriminate between NKT- and NK-mediated responses in vivo. These results indicate the use of different TCR-binding ceramides can provide a unique approach for understanding the intricate immunoregulatory contributions of these two cell types.

[Th1/Th2 balance in acute lymphoblastic leukemia in children]

Analysis of T lymphocytes cytokine profiles allows to differ subpopulations: Th1, Th2, Th3, Tr1. Aim of the study was to assess Th1/Th2 balance in acute lymphoblastic leukemia in children at diagnosis and during/after remission induction, especially during infections. Percentages of lymphocytes T producing IFN-gamma and IL-4 were assessed by flow cytometry. We noted the rise of lymphocytes T helper producing IFN-gamma (Th1) and percentage of lymphocytes T producing IL-4 at the beginning and during remission induction was higher than in control group. During fever/infection we observed the rise of lymphocytes Th1, and no change in Th2 percentage. Summarizing we suggest Th1/Th2 imbalance and Th2 predominance in acute lymphoblastic leukemia in children.

Suppression of collagen-induced arthritis by natural killer T cell activation with OCH, a sphingosine-truncated analog of ?-galactosylceramide

OBJECTIVE

OCH, a synthetic analog of alpha-galactosylceramide with a truncated sphingosine chain, stimulates natural killer T (NKT) cells to produce predominantly Th2 cytokines. Thus, OCH may be a potential agent for the treatment of Th1-mediated autoimmune diseases. This study was designed to evaluate the protective effects of OCH on collagen-induced arthritis (CIA) in mice.

METHODS

Mice were immunized with type II collagen (CII) and injected intraperitoneally twice per week with OCH, before or after the onset of CIA. They were monitored to assess the effect of OCH treatment on the severity of disease. Anti-CII antibodies and cytokine production were measured by enzyme-linked immunosorbent assay. Expression of cytokine genes was determined by quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

OCH inhibited CIA in wild-type C57BL/6 (B6) mice but not in NKT-deficient mice. OCH suppressed CIA in SJL mice, which are prone to autoimmune diseases and have a deficiency in the number and function of NKT cells which is similar to that in patients with autoimmune diseases, even after disease has already developed. Disease protection conferred by OCH correlated with its ability to selectively induce Th2 cytokine production mediated by NKT cells and to promote collagen-specific Th2 responses. Neutralization of interleukin-4 (IL-4) or IL-10 with monoclonal antibodies abolished disease protection by OCH, indicating a critical role for these cytokines.

CONCLUSION

Taken together, our findings suggest that OCH holds possibilities as a therapeutic agent for autoimmune diseases such as rheumatoid arthritis.

[Flow cytometric analysis of type 1 and type 2 subsets of CD4+ and CD8+ cells in intermittent allergic rhinitis and chronic urticaria--methodological aspects]

Human immune cells, included T helper cells and T cytotoxic/suppressor cells, may be divided into two distinct subtypes according to the profile of secreted cytokines. The allergic disorders are characterised by type 2 lymphocyte response, while the autoimmune diseases are associated with type 1 response. The aim of this study was to assess the usefulness of flow cytometric analysis of intracellular expression of cytokines typical for type 2 (IL-4) and type 1 response (IFN-gamma) in helper and cytotoxic/suppressor T cells in patients with chronic urticaria or intermittent allergic rhinitis. 10 subjects (6 male) with intermittent allergic rhinitis (a group ALER) and 6 subjects (1 male) with chronic urticaria (a group PP) were included into the study. The intracellular expression of IL-4 and IFN-gamma in CD4+ or CD8+ cells after stimulation with ionomycin/PMA was estimated by flow cytometer (FACSCalibur, Becton Dickinson) and serum levels of both cytokines were assessed with ELISA (R & D Systems) in all subjects. The percentage of CD4+ cell producing IFN-gamma was statistically higher in the PP group than in the ALER group, and the percentage of IL-4 producing CD8+ cells was also higher, although non significantly. The intracellular expression of IL-4 was comparable in both cell populations in the two examined groups. The surface expression of CD4 diminished after stimulation with PMA in all subjects. No correlations between serum level and intracellular expression of the examined cytokines were observed.

CONCLUSION

A tendency to the predominance of type 1 response of T lymphocytes was observed in chronic urticaria compared to intermittent allergic rhinitis.

A human dual-color enzyme-linked immunospot assay for simultaneous detection of interleukin 2- and interleukin 4-secreting cells

The enzyme-linked immunospot (ELISPOT) assay is an efficient technique for the enumeration of single cells secreting antibodies and cytokines. For simultaneous differentiation of individual cells producing interleukin-2 (IL-2) and interleukin-4 (IL-4) at a single cell level in human peripheral blood mononuclear cells (PBMCs), a human dual-color ELISPOT assay has been optimized. In the present system, the red spots corresponding to IL-2-secreting cells (T helper type 1, Th1, cells) were developed with horseradish peroxidase and the amino ethyl carbazole (AEC)/H2O2. The blue spots corresponding to IL-4-secreting cells (T helper type 2, Th2, cells) were developed with an alkaline phosphatase and the Vector blue. The usefulness of the assay method was tested. With this system, we could detect the IL-2- and IL-4-secreting cells simultaneously in human PBMCs of a juvenile rheumatoid arthritis (JRA) patient. This procedure provides useful information on clinical immune disorders.

Cyclophosphamide modulates CD4+ T cells into a T helper type 2 phenotype and reverses increased IFN-γ production of CD8+ T cells in secondary progressive multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system considered to be mediated by T helper type-1 cells. Several agents have been found to modify the disease course of MS, including interferon-beta1 (IFN-beta1), glatiramer acetate mitoxantrone. We have employed pulse therapy with cyclophosphamide in a selected group of patients with actively progressive disease. Chemokine receptors have been found to differentiate between polarized T helper type-1 (Th1) and type-2 (Th2) lymphocytes. The chemokine receptors CCR5 and CXCR3 are expressed primarily on Th1 cells and CCR3, CCR4 and CCR8 on Th2 cells. Previous studies of the expression of chemokine receptors in MS have shown that active MS plaques are infiltrated by CCR5(+) and CXCR3(+) T cells. Some of these T cells may express both CCR5 and CXCR3. These T cells are major producers of IFN-gamma, which worsens the clinical condition of patients with MS. We previously found that patients with MS had a high proportion of CXCR3(+) T cells and that those with chronic progressive MS had a high proportion of CCR5(+) T cells in their peripheral blood. We report here that in patients with secondary progressive MS, cyclophosphamide induces a marked increase in the percentage of CCR4(+) T cells that produce high levels of IL-4 and reverses the increase in the percentages of IFN-gamma-producing CCR5(+) and CXCR3(+) CD8(+) T cells. Furthermore, therapy with cyclophosphamide increases IL-4-producing CD4(+) T cells and reverses the increase in IFN-gamma-producing CD8(+) T cells. Our study shows that cyclophosphamide has immunomodulatory properties besides its suppressive effects, and that chemokine receptors can be important tools both for understanding the immune dysregulation in MS and for monitoring response to therapy.

[Effect of cytomegalovirus strain selection on stimulation of cytokine panel Th1/Th2]

CMV infection can undergoing as primary or secondary infection, which can be represented by reactivation of endogenous infection or by superinfection with another viral strain. Taking for consideration high prevalence of seropositive persons it may be concluded that superinfections occur quite often. For the other hand it is known, that differences among CMV strains are deep and regard as well viral structure as its biological properties. The aim of this study was investigation of immunological profile in range of cytokines production after stimulation with different CMV strains. The study was conducted with leukocytes obtained from CMV seropositive person cultivated and stimulated in vitro with AD169, Towne and Davis. After 24, 48, 72 and 96 hours incubation concentrations of IL-2, IL-4, IL-5, IL-10, INF-gamma and TNF-alpha in supernatants was measured by flow cytometry with Cytometric Bead Array technique. Obtained results allow to conclude that difference in level of stimulated cytokines and their panel is dependent on viral strain used. The experiment also allows to optimisation of stimulation conditions.

The Changes in the T helper 1 (Th1) and T helper 2 (Th2) Cytokine Balance During HIV-1 Infection are Indicative of an Allergic Response to Viral Proteins that may be Reversed by Th2 Cytokine Inhibitors and Immune Response Modifiers – a Review and Hypothesis

The HIV-1 infection in humans induces an early cellular immune response to react to the viral proteins with a cytotoxic T cell (CTL) response that fails to inhibit virus replication and the spread of the virus. It became evident that the progression of the disease causes chronic changes to the immune system of which a gradual increase in IgE antibodies is one of its features. When the HIV-1 epidemic began, the relation between the gradual increase in IgE content and AIDS was not understood, but later it became a marker for disease prognosis. The advances in the knowledge on T helper 1 (Th1) and T helper 2 (Th2) cells revealed that Th1 cells produce cytokines that stimulate the proliferation of CTLs. Th2 cells produce cytokines that are responsible for the activation of the humoral immune response in healthy people. Studies on both Th1 and Th2 cytokine synthesis revealed an aberration in HIV-1 infected people. Clerici and Shearer presented a hypothesis (1993) whereby Th1 cell activity declines and Th2 activity increases (the Th1 --> Th2 switch hypothesis) in HIV-1 infected people. In fact, experiments concerning this hypothesis ultimately supported the premise that the switch involves a critical change in the cytokine balance, which leads to the contraction of AIDS. However, the research community must still discern why such a Th1 --> Th2 switch takes place in infected people and how it can be reversed. The present review points to the fact that a similar Th1 --> Th2 switch constitutes the response of allergic people to environmental allergens. HIV-1 patients and allergic people that are exposed to allergens respond with an increased synthesis of Th2 cytokines and IgE, together with a decrease in Th1 cytokines. The studies on allergen-induced Th2 cells revealed that the Th2 cytokine IL-4 induces B cells to synthesize IgE, and cytokine IL-5 is the inducer of eosinophilia, just as in HIV-1 infection. The difference between the HIV-1 infection and allergies is the ability of IL-4 to induce the synthesis in T cells of the HIV-1 coreceptor CXCR4 that selects from the replicating virus a syncytium-inducing (SI) virus, a variant virus that replicates rapidly. The present hypothesis implicates the viral proteins in the induction of Th2 cytokine synthesis. This suggests that in viral proteins, allergen-like domains may be responsible for the activation of Th2 cytokine synthesis. Based on the analogy of the responses of humans to allergens and HIV-1, the following hypotheses is suggested: (a) Removal of allergen-like domains from viral genes by genetic engineering may provide viral proteins for vaccine development. (b) Attempts to treat allergic patients with IL-4 receptor inhibitors suggests that the "Th2 --> Th1 Reversion" constitutes a possible approach to inhibiting the Th2 cytokines and inducing a revival of the anti-viral Th1 response.

Fully Functional HLA B27-Restricted CD4+as well as CD8+T Cell Responses in TCR Transgenic Mice

The strong association of HLA B27 with spondyloarthropathies contrasts strikingly with most autoimmune diseases, which are HLA class II associated and thought to be mediated by CD4+ T lymphocytes. By introducing a human-derived HLA B27-restricted TCR into HLA B27 transgenic mice, we have obtained a functional TCR transgenic model, GRb, dependent on HLA B27 for response. Surprisingly, HLA B27 supported CD4+ as well as CD8+ T cell responses in vivo and in vitro. Further, HLA B27-restricted CD4+ T cells were capable of differentiation into a range of Th1 and Th2 T cell subsets with normal patterns of cytokine expression. The transgenic T cells were also able to enhance clearance of recombinant vaccinia virus containing influenza nucleoprotein in vivo. This is the first description of a human HLA class I-restricted TCR transgenic line. The existence of CD4+ MHC class I-restricted T cells has significant implications for immune regulation in autoimmunity and, in particular, in HLA B27-associated arthritis. We believe that this model provides a novel system for the study of unusual T cell behavior in vivo.