Naive human T cells can be a source of IL-4 during primary immune responses

Examining B-cell dynamics and responsiveness in different inflammatory milieus using an agent-based model

INTRODUCTION

B-cells are essential components of the immune system that neutralize infectious agents through the generation of antigen-specific antibodies and through the phagocytic functions of naïve and memory B-cells. However, the B-cell response can become compromised by a variety of conditions that alter the overall inflammatory milieu, be that due to substantial, acute insults as seen in sepsis, or due to those that produce low-level, smoldering background inflammation such as diabetes, obesity, or advanced age. This B-cell dysfunction, mediated by the inflammatory cytokines Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-α), increases the susceptibility of late-stage sepsis patients to nosocomial infections and increases the incidence or severity of recurrent infections, such as SARS-CoV-2, in those with chronic conditions. We propose that modeling B-cell dynamics can aid the investigation of their responses to different levels and patterns of systemic inflammation.

METHODS

The B-cell Immunity Agent-based Model (BCIABM) was developed by integrating knowledge regarding naïve B-cells, short-lived plasma cells, long-lived plasma cells, memory B-cells, and regulatory B-cells, along with their various differentiation pathways and cytokines/mediators. The BCIABM was calibrated to reflect physiologic behaviors in response to: 1) mild antigen stimuli expected to result in immune sensitization through the generation of effective immune memory, and 2) severe antigen challenges representing the acute substantial inflammation seen during sepsis, previously documented in studies on B-cell behavior in septic patients. Once calibrated, the BCIABM was used to simulate the B-cell response to repeat antigen stimuli during states of low, chronic background inflammation, implemented as low background levels of IL-6 and TNF-α often seen in patients with conditions such as diabetes, obesity, or advanced age. The levels of immune responsiveness were evaluated and validated by comparing to a Veteran's Administration (VA) patient cohort with COVID-19 infection known to have a higher incidence of such comorbidities.

RESULTS

The BCIABM was successfully able to reproduce the expected appropriate development of immune memory to mild antigen exposure, as well as the immunoparalysis seen in septic patients. Simulation experiments then revealed significantly decreased B-cell responsiveness as levels of background chronic inflammation increased, reproducing the different COVID-19 infection data seen in a VA population.

CONCLUSION

The BCIABM proved useful in dynamically representing known mechanisms of B-cell function and reproduced immune memory responses across a range of different antigen exposures and inflammatory statuses. These results elucidate previous studies demonstrating a similar negative correlation between the B-cell response and background inflammation by positing an established and conserved mechanism that explains B-cell dysfunction across a wide range of phenotypic presentations.

Novel xeno-free and serum-free culturing condition to improve piggyBac transposon-based CD19 chimeric antigen receptor T-cell production and characteristics

BACKGROUND AIMS

Chimeric antigen receptor (CAR) T cell is a novel therapy for relapse and refractory hematologic malignancy. Characteristics of CAR T cells are associated with clinical efficacy and toxicity. The type of serum supplements used during cultivation affects the immunophenotype and function of viral-based CAR T cells. This study explores the effect of serum supplements on nonviral piggyBac transposon CAR T-cell production.

METHODS

PiggyBac CD19 CAR T cells were expanded in cultured conditions containing fetal bovine serum, human AB serum or xeno-free serum replacement. We evaluated the effect of different serum supplements on cell expansion, transduction efficiency, immunophenotypes and antitumor activity.

RESULTS

Xeno-free serum replacement exhibited comparable CAR surface expression, cell expansion and short-term antitumor activity compared with conventional serum supplements. However, CAR T cells cultivated with xeno-free serum replacement exhibited an increased naïve/stem cell memory population and better T-cell expansion after long-term co-culture as well as during the tumor rechallenge assay.

CONCLUSIONS

Our study supports the usage of xeno-free serum replacement as an alternative source of serum supplements for piggyBac-based CAR T-cell expansion.

Cord Blood T Cells Expressing High and Low PKCζ Levels Develop into Cells with a Propensity to Display Th1 and Th9 Cytokine Profiles, Respectively

Low Protein Kinase C zeta (PKCζ) levels in cord blood T cells (CBTC) have been shown to correlate with the development of allergic sensitization in childhood. However, little is known about the mechanisms responsible. We have examined the relationship between the expression of different levels of PKCζ in CBTC and their development into mature T cell cytokine producers that relate to allergy or anti-allergy promoting cells. Maturation of naïve CBTC was initiated with anti-CD3/-CD28 antibodies and recombinant human interleukin-2 (rhIL-2). To stimulate lymphocyte proliferation and cytokine production the cells were treated with Phytohaemagglutinin (PHA) and Phorbol myristate acetate (PMA). Irrespective of the PKCζ levels expressed, immature CBTC showed no difference in lymphocyte proliferation and the production of T helper 2 (Th2) cytokine interleukin-4 (IL-4) and Th1 cytokine, interferon-gamma (IFN-γ), and influenced neither their maturation from CD45RA⁺ to CD45RO⁺ cells nor cell viability/apoptosis. However, upon maturation the low PKCζ expressing cells produced low levels of the Th1 cytokines, IFN-γ, IL-2 and tumour necrosis factor-alpha (TNF), no changes to levels of the Th2 cytokines, IL-4, IL-5 and IL-13, and an increase in the Th9 cytokine, IL-9. Other cytokines, lymphotoxin-α (LT-α), IL-10, IL-17, IL-21, IL-22 and Transforming growth factor-beta (TGF-β) were not significantly different. The findings support the view that low CBTC PKCζ levels relate to the increased risk of developing allergic diseases.

Perinatal and Early-Life Nutrition, Epigenetics, and Allergy

Epidemiological studies have shown a dramatic increase in the incidence and the prevalence of allergic diseases over the last several decades. Environmental triggers including risk factors (e.g., pollution), the loss of rural living conditions (e.g., farming conditions), and nutritional status (e.g., maternal, breastfeeding) are considered major contributors to this increase. The influences of these environmental factors are thought to be mediated by epigenetic mechanisms which are heritable, reversible, and biologically relevant biochemical modifications of the chromatin carrying the genetic information without changing the nucleotide sequence of the genome. An important feature characterizing epigenetically-mediated processes is the existence of a time frame where the induced effects are the strongest and therefore most crucial. This period between conception, pregnancy, and the first years of life (e.g., first 1000 days) is considered the optimal time for environmental factors, such as nutrition, to exert their beneficial epigenetic effects. In the current review, we discussed the impact of the exposure to bacteria, viruses, parasites, fungal components, microbiome metabolites, and specific nutritional components (e.g., polyunsaturated fatty acids (PUFA), vitamins, plant- and animal-derived microRNAs, breast milk) on the epigenetic patterns related to allergic manifestations. We gave insight into the epigenetic signature of bioactive milk components and the effects of specific nutrition on neonatal T cell development. Several lines of evidence suggest that atypical metabolic reprogramming induced by extrinsic factors such as allergens, viruses, pollutants, diet, or microbiome might drive cellular metabolic dysfunctions and defective immune responses in allergic disease. Therefore, we described the current knowledge on the relationship between immunometabolism and allergy mediated by epigenetic mechanisms. The knowledge as presented will give insight into epigenetic changes and the potential of maternal and post-natal nutrition on the development of allergic disease.

Implantation associated changes in expression profile of indoleamine-2, 3-dioxygenase 1, Th1-Th2 cytokines and interferon-stimulated genes on neutrophils and peripheral blood mononuclear cells of crossbred cows

Effective bidirectional communication between the embryo and dam improves the reproductive efficiency of dairy cows. Possible role of immunosuppressive indolamine-2, 3-dioxygenase 1 (IDO1) enzyme in the regulation of maternal systemic cytokine balance/shift during early pregnancy establishment along with various interferon-stimulated genes (ISGs) expression in neutrophils and peripheral blood mononuclear cell (PBMCs) were investigated in crossbred cows. Blood was collected on days 0 i.e. day of Artificial Insemination (AI), 10, 18 and 36 post-AI followed by isolation of neutrophils and PBMCs for gene expression study of IDO1, anti-inflammatory cytokines (IL-4, IL-10 and TGFβ1), pro-inflammatory cytokines (IFNγ and TNFα) and ISGs (ISG15, MX1, MX2, OAS1) in pregnant and non-pregnant cows. Cows were grouped as pregnant and non-pregnant after pregnancy confirmation by non-return to heat, ultrasonography, per rectal examination along with progesterone and IFNτ assay. Significantly (P < 0.05) higher relative mRNA expression of IDO1 and anti-inflammatory cytokines on days 10 and 18 post-AI were observed in both neutrophils and PBMCs of pregnant cows. Pregnant cows showed significantly (P < 0.05) higher mRNA transcripts of IFNγ and TNFα genes on days 18 post-AI in both neutrophils and PBMCs. Expression of ISGs was higher (P < 0.05) on day 10^th and 18^th post AI in both the neutrophils and PBMCs of pregnant cows. The study indicates that systemic immune regulation by IDO1 (through cytokine shift) and ISGs in peripheral immune cells are essential for the establishment of pregnancy and may be targeted in future as biomarkers for pregnancy diagnosis.

Restricted CD4+ T cell receptor repertoire impairs cognitive function via alteration of Th2 cytokine levels

Despite the effects of CD4+ T cell dysfunction on cognitive and behavioral impairment are well established, the effects of Th2 cytokines on the adult hippocampal neurogenesis and cognitive function in restricted CD4+ T cell receptor (TCR) repertoire model have not been fully elucidate. We found that mice with restricted CD4+ repertoire TCR showed decreased adult hippocampal neurogenesis using OT-II mice. Moreover, we demonstrated that OT-II mice showed increased Th2 cytokine levels in peripheral organs and IL-4 levels in brain. Taken together, altered Th2 cytokine levels may impact learning and memory via impaired adult neurogenesis in restricted CD4+ repertoire TCR mice.

Impaired Memory in OT-II Transgenic Mice Is Associated with Decreased Adult Hippocampal Neurogenesis Possibly Induced by Alteration in Th2 Cytokine Levels

Recently, an increasing number of studies have focused on the effects of CD4+ T cell on cognitive function. However, the changes of Th2 cytokines in restricted CD4+ T cell receptor (TCR) repertoire model and their effects on the adult hippocampal neurogenesis and memory are not fully understood. Here, we investigated whether and how the mice with restricted CD4+ repertoire TCR exhibit learning and memory impairment by using OT-II mice. OT-II mice showed decreased adult neurogenesis in hippocampus and short- and long- term memory impairment. Moreover, Th2 cytokines in OT-II mice are significantly increased in peripheral organs and IL-4 is significantly increased in brain. Finally, IL-4 treatment significantly inhibited the proliferation of cultured adult rat hippocampal neural stem cells. Taken together, abnormal level of Th2 cytokines can lead memory dysfunction via impaired adult neurogenesis in OT-II transgenic.

Low cord blood Foxp3/CD3γ mRNA ratios: a marker of increased risk for allergy development

BACKGROUND

Data from birth cohort studies suggest that increased cord blood total IgE and reduced cord blood regulatory T cells increase the risk of developing allergic sensitization and atopic dermatitis.

OBJECTIVE

We here addressed whether serum total IgE and hen's egg-specific IgE levels at birth and at age 1 year differed between healthy and allergic children in a Belgian birth cohort (FONIA). We furthermore studied whether these parameters as well as cord blood Foxp3/CD3γ mRNA levels might predict the allergic outcome.

METHODS AND RESULTS

Children (n = 84) were clinically assessed at the ages of 6, 12, 18, and 24 months and at 6 years. Cord blood total IgE levels above 0.35 kU/L predicted early (i.e. before or at the age of 2 years) allergy development. Presence of serum IgE antibodies to hen's egg (cut-off 0.05 Ua/mL) at the age of 1 year was associated with early as well as late (i.e. between the age of 2 and 6 years) allergy development. Cord blood Foxp3/CD3γ mRNA ratios were significantly lower in early allergic children and levels below 0.32 predicted the allergic outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

Low cord blood Foxp3/CD3γ mRNA ratios are highly predictive for early allergy development, whereas specific IgE levels to hen's egg white above 0.05 Ua/mL at age 1 year predict allergy development in general.

T-box 21 transcription factor is responsible for distorted T(H)2 differentiation in human peripheral CD4+ T cells

BACKGROUND

Regardless of T(H)1/T(H)2 theory, CD4(+) T cells of patients with allergic asthma, a typical T(H)2 disease, and those of healthy subjects expressed equivalent levels of IFN-gamma, even though T(H)2 cytokines were significantly upregulated in asthmatic patients.

OBJECTIVE

The mechanisms underlying distorted T(H)2 cell polarization in human T cells were elucidated.

METHODS

Cytokine-producing activity and the expression of T(H)1/T(H)2-specific transcription factors in naïve, T(H)1/T(H)2, or both CD4(+) T cells derived from human peripheral and cord blood were comparatively analyzed. The mechanisms of the differential expression of T-box 21 transcription factor (T-bet) in the cells were assessed by determining the chromatin accessibility at the TBX21 gene. The functional roles of T-bet and other transcription factors in human T(H)1/T(H)2 differentiation were further investigated.

RESULTS

T(H)2 cells derived from naive CD4(+) T cells in peripheral blood but not in cord blood produced IFN-gamma. T-bet was expressed in peripheral, but not cord blood, resting naive T cells. Consistently, the accessibility at the proximal TBX21 gene promoter in peripheral naive T cells was higher than that in cord blood naive T cells. IFN-gamma-producing activity was induced in T(H)2-differentiated cord blood T cells by means of ectopic expression of T-bet. In addition, a reduction of T-bet in peripheral T cells suppressed IFN-gamma production. T-bet not only upregulated IFN-gamma but also downregulated IL-4 and IL-13 gene transcription, independently of the modification of T(H)1/T(H)2 balance.

CONCLUSION

The expression of T-bet at a naive stage is crucial for the development of IFN-gamma-producing T cells in human peripheral blood, even in T(H)2-related diseases.

Effect of HLA genotype or CTLA-4 polymorphism on cytokine response in healthy children

Type 1 diabetes (T1D) is considered to be a T-cell-mediated autoimmune disease in which genetic predisposition is affected by HLA class II alleles and polymorphisms in cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene. We tested the hypothesis whether these T1D-related gene polymorphisms modulate cytokine response and thus contribute to the development of autoimmunity. The study includes 67 non-diabetic children, typed for HLA class II alleles and CTLA-4 polymorphisms (+49A/G, CT60A/G, CTBC217_1C/T). We measured cytokine secretion of peripheral blood mononuclear cells after stimulation with tetanus toxoid (TT), polio virus, coxsackie virus B4, pertussis toxin (PT) and phytohemagglutinin (PHA). We saw higher IL-13 response to TT in individuals with DR3-DQ2 haplotype (P = 0.002). HLA class II protective haplotype, DR2-DQ6, showed association with increased production of IFN-gamma (P < 0.001) and IL-2 (P = 0.005) in response to polio virus. In children with the autoimmunity-related homozygous genotypes CTLA-4 +49G/G, CT60G/G and CTBC217_1T/T, we found enhanced PT- and PHA-induced IFN-gamma production (P < 0.05). The cytokine responses to studied antigens were weakly modified by HLA class II risk haplotypes, and children with T1D-associated HLA risk haplotypes are not specifically inclined to develop an immune response in general. Higher IFN-gamma and IL-2 response to enterovirus in children with HLA class II protective haplotype DR2-DQ6 could be of importance in the protection from T1D-associated enterovirus infections. All autoimmunity related CTLA-4 polymorphisms were associated with enhanced IFN-gamma. This suggests impaired downregulation of cellular immunity by these CTLA-4 polymorphisms.

Mast cells in diffuse large B-cell lymphoma; their role in fibrosis

AIMS

Mast cells (MCs) are associated with fibrosis in various diseases. MCs comprise two phenotypes: the MC(TC) phenotype contains tryptase and chymase, whereas the MC(T) phenotype contains tryptase. Interleukin (IL)-4 promotes the development of MC(TC) from the MC(T) phenotype. The aim of this study was to determine the relationship between MC phenotypes and fibrosis in diffuse large B-cell lymphoma (DLBCL).

METHODS AND RESULTS

We examined the distribution and density of MCs in 50 DLBCL and 20 reactive lymph nodes, and evaluated MC phenotypes and IL-4-expressing cells. To detect MCs, immunohistochemistry for tryptase and chymase was performed. The 50 DLBCLs were histologically divided into three groups: no fibrosis (32 cases), reticular type (eight cases) showing reticular fibrosis, and bundle type (10 cases) showing collagenous bundles. The density of tryptase-positive MCs was higher than that of chymase-positive MCs. The densities of tryptase-positive and chymase-positive MCs in fibrotic areas were significantly higher than those in the cellular areas in the reticular and bundle groups. Double immunostaining revealed that MCs in DLBCL comprised MC(T) and MC(TC) phenotypes. Chymase-positive MCs and T lymphocytes expressed IL-4. Although there were few chymase-positive MCs in reactive lymph nodes, the density of tryptase-positive MCs was not different from that in the 'no fibrosis' group.

CONCLUSIONS

Tryptase-positive and chymase-positive MCs are associated with fibrosis in DLBCL.

Mast cell chymase expression inHelicobacter pylori-associated gastritis

AIMS

To study the role of mast cell chymase in the inflammatory processes of human chronic gastritis. Experimental studies have shown that mast cell chymase stimulates inflammatory cell accumulation, and contributes to angiotensin II formation.

METHODS AND RESULTS

Tissue sections from human stomachs with Helicobacter pylori-associated gastritis (surgery/autopsy n = 20; biopsy n = 16) and normal stomachs (n = 10) were studied using immunohistochemical single and double labelling techniques. Monoclonal antibodies used were directed against mast cell chymase, tryptase, neutrophils (CD66b, elastase, and myeloperoxidase), macrophages, T-lymphocytes, and interleukin (IL)-4. The expression of angiotensin-converting enzyme and angiotensin II type 1 receptor was investigated using immunohistochemical analysis and the reverse transcription-polymerase chain reaction. The number of chymase-positive mast cells was significantly higher (P < 0.0001) in H. pylori-associated gastritis than in normal stomachs. Increased expression of chymase in inflamed mucosa was closely related to an increase in the accumulation of neutrophils, macrophages, T-lymphocytes, and IL-4-positive cells. The expression of angiotensin-converting enzyme and angiotensin II type 1 receptor was not altered in gastritis specimens.

CONCLUSIONS

These observations suggest that mast cell chymase may be an important mediator in the inflammatory processes of human H. pylori-associated gastritis.

Different antigens trigger different Th1/Th2 reactions in neonatal mononuclear cells (MNCs) relating to T-bet/GATA-3 expression

Neonates are known to have poor cellular immunity, especially poor Th1 response. We investigated how neonatal mononuclear cells raised different Th1/Th2 reactions in response to different antigens. Employing Dermatophagoides pteronyssinus (Der p) extract and varicella zoster virus (VZV) as antigens, we assessed Th1/Th2 reactions as demonstrated by IL-4/IFNgamma production and mRNA expression, and transcriptional factors T-bet/GATA-3 mRNA expression in mononuclear cells from human umbilical cord blood (CBMC). Results showed that VZV induced a dramatic increase of IFNgamma production by adult peripheral blood mononuclear cells (PBMC), whereas VZV did not drive CBMC to release significant IFNgamma production (1614.7+/-362.0 vs. 49.0+/-29.3,p<0.005). However, Der p induced higher IFNgamma production by CBMC than VZV (298.1+/-171.8 vs. 49.0+/-29.3, P=0.047). In contrast, VZV did not induce significant IL-4 production either by CBMC or by PBMC. Der p induced a comparative IL-4 production by CBMC and PBMC (2.58+/-0.84 vs. 2.04+/-0.37, p>0.05). A real-time RT-PCR analysis of IL-4 and IFNgamma mRNA expression showed that VZV induced a significantly higher IFNgamma, but not IL-4, mRNA expression in PBMC than CBMC. Der p did not induce significant difference of IFNgamma or IL-4 mRNA expression in PBMC and CBMC. VZV enhanced Th1-related transcription factor T-bet mRNA expression, in association with later down-regulation of Th2-related GATA-3 mRNA expression in PBMC. However, VZV did not up-regulate T-bet or down-regulate GATA-3 expression significantly in CBMC. In contrast, Der p induced an early GATA-3 expression and later T-bet expression in CBMC. These results suggest that different antigens trigger various Th1/Th2 reactions in PBMC and CBMC resulting from kinetic changes of T-bet/GATA-3 expression.

Allergen-induced cytokine secretion in atopic and non-atopic asthmatic children

Atopic asthma is characterized by excessive T helper 2 (Th2)-like immunity to allergens in the bronchial mucosa. The Th2-cytokine interleukin (IL)-4 induces IgE production, while the Th2-cytokine IL-5 promotes eosinophilic inflammation in the airways of asthmatics. Most asthmatics are atopic, but a subgroup is non-atopic. We hypothesize that allergen-induced Th2, particularly IL-5, responses can be observed in peripheral blood in both atopic and non-atopic asthmatic children but not in healthy control children. The aim of the present study was to determine IL-4, IL-5, IL-9, IL-10, IL-13 and IFN-gamma secretion induced from peripheral blood mononuclear cells (PBMC) by a broad panel of inhalant allergens (timothy, cat, birch, dog and house dust mite) in asthmatic children with and without sensitization. The study included 13 atopic asthmatic, 5 non-atopic asthmatic, and 12 non-atopic non-asthmatic children. PBMC were stimulated with allergens and cytokine production was measured with enzyme-linked immunosorbent assay (ELISA). Higher levels of cat and dog antigen-induced IL-5 release were more commonly observed in both atopic and non-atopic asthmatics than in controls. Children with atopic, but not non-atopic, asthma produced higher levels of allergen-induced IL-4 and IL-9 than controls. Non-atopic asthmatics produced more IL-10 than atopic asthmatics after cat stimulation. High levels of eosinophilia-associated IL-5 responses are induced by cat and dog allergen in both atopic and non-atopic asthmatic children. The Th2 cytokines IL-4 and IL-9 were associated only with atopic asthma, probably due to their IgE-inducing properties.

Naïve CD4+ T cells from patients with atopic dermatitis show an aberrant maturation towards IL-4-producing skin-homing CLA+ cells

Overproduction of interleukin-4 (IL-4) has been reported in lesional and in peripheral T cells from patients with atopic dermatitis (AD). It is not clear whether the development of IL-4-producing T helper type 2 (Th2) cells from naïve precursors is an intrinsic phenomenon of T cells or whether other, extrinsic factors play a significant role. To analyze these alternatives, we investigated the IL-4 production of effector T cells generated in vitro from highly purified CD4+ CD45RA+ naïve T cells in the absence of signals derived from antigen-presenting cells. Effector T cells generated from naïve precursors from both AD and healthy donors produced comparable amounts of IL-4 after restimulation. Priming in the presence of exogenous IL-4 enhanced the production of IL-4 while neutralizing endogenously produced IL-4 abolished IL-4 production similarly in atopic and healthy T cells. A subset of effector T cells acquired the expression of the cutaneous lymphocyte antigen (CLA). The frequency of CLA+ T cells was not different between atopic and healthy donors. CLA+ T cells, differentiated from naïve atopic, but not healthy T cells, showed a preferential Th2 cytokine profile as assessed by intracellular cytokine staining. Also effector T cells derived from atopic patients without dermatitis tended to show this imbalance, although it was not significantly different to healthy controls. This Th2 cytokine profile did not develop when naïve T cells were cultured in the presence of IL-12. In conclusion, high IL-4 production in developing T cells from AD patients was associated with CLA expression, the net IL-4 production of all effector CD4+ T cells, however, was similar to IL-4 production by T cells from healthy donors.

Allergen-induced Th1 and Th2 cytokine secretion in relation to specific allergen sensitization and atopic symptoms in children

BACKGROUND

Allergic diseases are believed to be due to T helper (Th)2-like immunity to allergens in affected tissues, and immune responses to allergens are characterized by a cross-regulation between Th1 and Th2 cells. Atopic individuals may develop IgE antibodies to only one or more allergens. However, the mechanisms behind sensitization to a specific allergen, e.g. why an individual develops IgE to cat but not birch, are not known. Our aim was to study birch- and cat-induced Th1 and Th2 cytokine secretion in children who were sensitized to birch but not to cat, and vice versa.

MATERIALS AND METHODS

The subjects in the study were 60 12-year-old children. Seventeen of the children were sensitized (skin prick test and circulating IgE positive) to birch but not cat, 13 were sensitized to cat but not birch, 11 were sensitized both to birch and cat, and 19 children were skin prick test and circulating IgE negative. Forty-six children had a history of atopic symptoms, and 42 of them had current symptoms. Peripheral blood mononuclear cells were separated from venous blood and stimulated with cat or birch allergen. The levels of IL-4, IL-5, IL-9, IL-10, IL-13 and IFN-gamma in the cell supernatants were analysed by ELISA.

RESULTS

Sensitized children produced more of the Th2 cytokines IL-4, IL-5, IL-9 and IL-13 than non-sensitized atopic and non-atopic children in response to stimulation with the allergen they were sensitized to. High levels of the Th2 cytokines IL-4 and IL-5 and low levels of the anti-inflammatory cytokine IL-10 were associated with atopic symptoms, and high cat-induced IL-9 levels with asthma.

CONCLUSIONS

The Th2 cytokines IL-4, IL-5, IL-9 and IL-13 were all commonly detected in sensitized children after stimulation with the specific, in contrast to an unrelated, allergen. Atopic symptoms were associated with increased levels of IL-4 and IL-5 and tended to be associated with low levels of IL-10, and asthma with high cat-induced IL-9 levels.

CD40L-induced IL-12 production is further enhanced by the Th2 cytokines IL-4 and IL-13

Interaction of the CD40L (CD154) molecule on activated T cells with its receptor, CD40, on macrophages and dendritic cells (DC) provides a strong signal for interleukin (IL)-12 production. As IL-12 is the most important factor in driving Th precursor (Thp) cells into T(h)elper 1 cells, CD40-CD40L interactions strongly promote Th1 differentiation. Th2 cytokines (IL-4, IL-13, IL-10) on the other hand, are known to inhibit Th1 differentiation, and to promote either directly or indirectly, Th2 differentiation. Inhibition of lipopolysaccharide (LPS)-induced IL-12 production by IL-4, IL-13 and IL-10 is supposed to be one such mechanism. However, we here report that IL-4 and IL-13 enhance p70 IL-12 production and p40 mRNA transcription by human monocytes when the latter are stimulated trough triggering of CD40. This effect on IL-12 induction is most clear in the presence of interferon (IFN)-gamma, which upregulates CD40 expression. IL-10 potently inhibits IL-12 production. The increased IL-12 production in the presence of IL-4 and IL-13 is however, not the indirect result of a reduction in IL-10 production, but is most likely owing to a direct effect of IL-4 and IL-13. We conclude that IL-4 and IL-13 enhance rather than decrease the IL-12 production by human monocytes during interaction with T cells. This effect can potentially contribute in vivo to switching of an ongoing Th2 response towards a Th1 response and the findings also support the dominant effect of CD40/CD40L interaction on Th1 development, even in the presence of Th2 cytokines.

Effects of co-stimulation by CD58 on human T cell cytokine production: a selective cytokine pattern with induction of high IL-10 production

CD58 is the ligand for the CD2 molecule on human T cells and has been shown to provide a co-stimulatory signal for T cell activation. However, its physiological role is still unclear. We studied the effects of co-stimulation by CD58 on the production of T(h)1-type (IL-2- and IFN-gamma) or T(h)2 type (IL-4, IL-5 and IL-10) cytokines in an in vitro culture system of purified human T cells with CD58-transfected P815 cells and with anti-CD3 as the primary stimulus. Co-stimulation of T cells by CD58 potently induced IL-10 and IFN-gamma production (at the protein and at the mRNA level), and transforming growth factor-ss production (at the mRNA level), comparable to what can be found in CD80 co-stimulated T cell cultures. In contrast, we found low to absent IL-2, IL-4, IL-5, IL-13 and tumor necrosis factor-alpha production after CD58 co-stimulation, and this was not due to suppressive effects of endogenously produced IL-10. CD80 co-stimulation strongly induced all these cytokines. Intracellular staining for cytokine expression revealed the existence of a T cell subpopulation induced by CD58 co-stimulation to produce both IFN-gamma and IL-10. We furthermore found that the selective cytokine profile induced by CD58 co-stimulation is further accentuated by rIL-12 and by rIFN-alpha. Using cyclosporin A as an inhibitor of the calcineurin enzyme, we could show that production of all cytokines in this system is calcium dependent. CD58 co-stimulation thus induces a cytokine pattern corresponding to that described for T regulatory (T(r)) 1 cells and to the pattern reported to be induced by the newly identified B7 family member, B7-H1.

Chromosomally clonal T cells in the skin, blood, or lymph nodes of two Sezary syndrome patients express CD45RA, CD45RO, CDw150, and interleukin-4, but no interleukin-2 or interferon-gamma

Cutaneous T cell lymphomas are considered to represent a clonal malignancy of mature T lymphocytes of the T helper memory subtype. A method enabling the direct identification of clonal malignant cells in tissue and, at the same time, identification of the surface molecules they express has not been available, however. We have developed an application of the FICTION technique (simultaneous fluorescence immunophenotyping and interphase cytogenetics) to be used on fresh blood, skin, and lymph node samples. A prerequisite for this method is the characterization of a moleculocytogenetic clone in order to select the proper probes. With this method, we demonstrate that the true malignant cells express CD3, CD4, and CD45RO in the blood, skin, and lymph nodes of two Sezary syndrome patients. The majority of these cells express also CD45RA (albeit of varying intensity) and CDw150. The cytokine expression pattern of the clonal cells in skin and lymph nodes was interleukin-2 and interferon-gamma negative and interleukin-4 positive. Interleukin-10 expression varied. The malignant cells did not express granzyme B, thus indicating that they do not have cytotoxic properties. Clonal cells with the same constant phenotype could be found even in lymph nodes with not yet morphologically identifiable malignant cells. This is the first report of the FICTION method applied directly on skin tissue. With this method we demonstrated that the chromosomally clonal cells in these two cases of Sezary syndrome could be intermediate forms between naïve CD45RA+ and CD45RO+ Th2 cells.