Culture conditions for the detection of allergen-specific T-cell reactivity in cord blood: influence of cell number

Cytokine levels in supernatants of whole blood and mononuclear cell cultures in adults and neonates reveal significant differences with respect to interleukin-13 and interferon-gamma

Findings regarding cytokine levels in neonates and their impact on the development of allergic diseases are controversial. This might be attributed to different laboratory approaches. To compare cytokine levels in supernatants of whole blood (WB) and mononuclear cell (MC) cultures in response to unspecific and allergen specific stimuli. A total population of n = 25 healthy full-term neonates and n = 25 adults was recruited. WB was diluted 1 in 5 and incubated with phytohaemagglutinine (PHA; 20 mug/ml) and the cows' milk protein betalactoglobulin (BLG) for 24 and 120 h. In parallel, cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) were isolated, and cells were cultured with PHA and BLG in the same concentrations in a medium supplemented with fetal calf serum (FCS) and in a serum- free medium (only PBMC from adults). The cytokines interferon-gamma (IFN-gamma), interleukin-10 (IL-10), and IL-13 in the cell culture supernatants were measured using the ELISA technique. IFN-gamma and IL-10 levels in response to PHA in supernatants of MC of neonates were significantly lower compared to that in adults (p < 0.05, Wilcoxon two-sample test). IL-13 levels were significantly higher in response to PHA in neonates. In adults, only levels of IL-10 were significantly correlated in WB and PBMC cultures (PHA: r(S) 0.6; p = 0.002; BLG: r(S) 0.54; p = 0.005). In neonates, IL-10 (PHA: r(S) 0.77; p < 0.001; BLG: r(S) 0.63; p < 0.001) and IFN-gamma (PHA: r(S) 0.48; p = 0.02; BLG: r(S) 0.4; p < 0.047) were significantly correlated. Supernatants of PBMC cultured with an FCS-supplemented medium showed a significant lower IFN-gamma release (PHA 1297 pg/ml; BLG 2762 pg/ml) compared to serum-free cell cultures (PHA 6592.5 pg/ml, p < 0.0001; BLG 14228 pg/ml, p = 0.04). IFN-gamma and IL-13 levels in WB and MC supernatants revealed significant differences. Our data indicate the need for thoroughly defined and standardized culture conditions for the detection of in vitro cytokine levels.

Sulphidoleukotriene release of cord blood basophils in response to allergen stimulation correlates with neither a family history of atopy nor a subsequent development of atopic eczema

OBJECTIVE

We tested a possible relationship between sulphidoleukotriene (SLT) release of cord blood (CB) basophils, a family history of atopy (HA) and subsequent development of atopic eczema. Population and methods A cohort of 86 neonates were involved (48.8% males; 46.5% with a positive HA(+)). CB samples were analysed for in vitro SLT release quantified by ELISA, and in a subgroup for basophilic activation (CD 63 expression) by flow cytometry in response to a positive control (anti-IgE-receptor antibody), an allergen-mix (TOP and PTOP), egg white (EW), egg yolk (EY), and the purified allergens beta-lactoglobulin (BLG) and alpha-lactalbumin (ALA).

RESULTS

Median concentrations of SLT were 124.2 (negative), 3871.5 (positive), 123.9 (TOP), 128.5 (PTOP), 113.1 (EW), 108.4 (EY), 125.2 (BLG) and 122.3 (ALA) pg/mL. Groups of HA(+) and HA(-) show no difference in all analysed allergens. An allergen-specific SLT release (defined as SLT>125 pg/mL above individual baseline and a stimulation index >2) was detected in 98% (positive control), 5% (TOP), 7% (BLG), 3% (ALA) and 2% (EW and EY), respectively. After a median observation period of 18 months, n=7 out of 70 children developed an atopic eczema, but we observed no association between CB SLT release (positive response to at least one tested allergen).

CONCLUSION

Allergen-specific SLT release is detectable in 15.5% of healthy neonates, irrespective of their family history of atopy. However, early allergen-specific SLT release is not predictive for the development of atopy.

Lactobacillus GG has in vitro effects on enhanced interleukin-10 and interferon-gamma release of mononuclear cells but no in vivo effects in supplemented mothers and their neonates

BACKGROUND

The value of probiotics for primary prevention is controversial. Moreover, only little is known about the underlying immunological mechanisms of action. Therefore, we assessed the proliferative response and cytokine release in cultures of isolated mononuclear cells from pregnant women and their neonates supplemented with Lactobacillus GG (LGG) or placebo.

METHODS

In a double-blind, placebo-controlled prospective trial, pregnant women with at least one first-degree relative or a partner with an atopic disease were randomly assigned to receive either the probiotic LGG (ATCC 53103; 5 x 10(9) colony-forming units LGG twice daily) or placebo 4-6 weeks before expected delivery, followed by a post-natal period of 6 months. Cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) of the corresponding mother were isolated from cord blood and peripheral blood (n=68). The proliferative response of CBMC and PBMC was expressed as the stimulation index (SI), which was calculated according to the ratio between the mean counts per minute (c.p.m.) values measured in the wells with stimulated cells and the mean c.p.m. values measured in the wells with unstimulated cells. Additionally, the cytokines IFN-gamma, IL-10 and IL-13 in the cell culture supernatants were measured using the ELISA technique.

RESULTS

No difference was observed between the LGG-supplemented group and the placebo group in terms of the proliferative capacity of maternal or neonatal cord blood cells in response to IL-2, beta-lactoglobulin or LGG. In vitro stimulation with LGG resulted in significantly enhanced release of IL-10 and IFN-gamma, compared with cytokine release in unstimulated controls. However, this phenomenon was observed in supernatants of maternal and neonatal MC in both groups, independent of prior supplementation with LGG.

CONCLUSION

LGG has in vitro effects on enhanced IL-10 and IFN-gamma release of mononuclear cells. However, supplementation with LGG during pregnancy did not alter the proliferative capacity or cytokine pattern in their recipients.

Most of diaplacentally transferred allergen is retained in the placenta

BACKGROUND

Transplacental transfer of nutritive and inhalant allergens has been described being potentially responsible for a series of events leading to antigen-specific immune responses in the fetus. As such, cord blood T cell responses appear ubiquitously. However, studies failed to reveal a consistent dose-response relationship between antenatal allergen exposure and allergen-specific cellular reactivity in cord blood.

OBJECTIVE

To examine the transfer process of allergens (ovalbumin (OVA), beta-lactoglobulin (BLG), birch pollen allergen Bet v1) in placental tissue (BeWo cell line, ex vivo placenta model).

METHODS

The choriocarcinoma cell line BeWo was used to study the allergen uptake and transfer experiments in vitro. In the ex vivo placenta model the contribution of different placental compartments was evaluated. For this, immuno-histochemistry, immuno-electronmicroscopy and ELISA techniques were applied using monoclonal antibodies to Bet v1, OVA and -BLG.

RESULTS

In vitro transfer studies on a BeWo cell-layer revealed an intracellular allergen uptake and a trans-trophoblastic allergen transfer, which was temperature- and concentration dependent, pH sensitive and asymmetric. Allergen-specific staining of placental tissue after allergen perfusion (BLG) demonstrated bulk of the allergen in the syncytio-trophoblastic cell layer and minor staining in the villous stroma and in the endothelium of fetal vessels. Immunogold staining revealed an accumulation of the perfused allergen in the trophoblastic basement membrane.

CONCLUSION

In vitro/ex vivo trans-trophoblastic and trans-placental allergen transfer is shown with an accumulation of most of the allergen in placental tissues, potentially explaining the missing direct dose-response relationship between prenatal (maternal) allergen exposure and allergen-specific cellular reactivity in cord blood.

Absence of systemic immunologic changes during dose build-up phase and early maintenance period in effective specific sublingual immunotherapy in children

BACKGROUND

Sublingual immunotherapy (SLIT) has been reported to be a safe treatment for inhalant allergies in children. Yet the immunologic mechanisms resulting in clinical improvement are poorly understood.

OBJECTIVE

To identify early systemic immunologic changes during the first 8 weeks of clinically effective SLIT to grass pollen, tree pollen or house dust mite in paediatric patients with allergic rhinoconjunctivitis and/or asthma.

METHODS

Peripheral blood mononuclear cells and plasma samples of 13 children with reduced symptoms after 1 year of SLIT were obtained before therapy and at 2 and 8 weeks after the initiation of SLIT. Allergen-specific lymphocyte proliferation assays were performed, and allergen-induced cytokine production (IL-2, IL-4, IL-10, IFN-gamma, and TGF-beta(1)) was measured by ELISA and flow cytometry. Allergen-specific IgE, IgG1, IgG4, and IgA levels in plasma samples were determined in ELISA.

RESULTS

During the first 8 weeks of successful SLIT, allergen-specific lymphoproliferation (n=13) as well as levels of allergen-specific intracellular (n=8) and secreted cytokines (n=9) did not change significantly. In addition, no alterations in levels of allergen-specific Igs (n=7) were observed.

CONCLUSION

We could not find any early systemic immunologic changes during the first 8 weeks of clinically effective SLIT to inhalant allergens in paediatric patients with allergic rhinoconjunctivitis and/or asthma.

Human milk--derived oligosaccharides and plant-derived oligosaccharides stimulate cytokine production of cord blood T-cells in vitro

Human milk contains large amounts of free oligosaccharides (HMOs). HMOs have been shown to exert antiinflammatory properties, and evidence for their immunomodulatory effects is increasing. The purpose of this study was to evaluate influences of two human breast milk-derived oligosaccharide samples (neutral and acidic oligosaccharides), and of a low-molecular-weight fucoidan on cytokine production and activation of cord blood mononuclear cells. Cord blood mononuclear cells from randomly chosen healthy newborns were co-cultured with the oligosaccharide samples. By means of flow cytometry, intracellular cytokine production (d 20) and surface marker expression of T cells (d 5) were measured. In vitro-induced Ig levels were quantified nephelometrically (total IgG1) and by ELISA (total IgE) in the supernatant of cell cultures. The acidic oligosaccharide fraction increased the percentage of interferon-gamma producing CD3+CD4+ and CD3+CD8+ cells (p < 0.05) and the IL-13 production in CD3+CD8+ cells (p < 0.05). In acidic oligosaccharide cultures, CD25+ expression on CD3+CD4+ cells was significantly elevated (p < 0.05). Low-molecular-weight fucoidan induced IL-4 production in CD3+CD4+ T cells (p < 0.05) and IL-13 production in CD3+CD8+ T cells (p < 0.05), whereas interferon-gamma production remained unaffected in both T-cell populations. Ig production (total IgE and total IgG1) remained unaffected. Human milk-derived oligosaccharides and plant-derived oligosaccharides affect the cytokine production and activation of cord blood derived T cells in vitro. Therefore, oligosaccharides and, in particular, acidic oligosaccharides may influence lymphocyte maturation in breast-fed newborns.

Immunostimulatory potential of beta-lactoglobulin preparations: effects caused by endotoxin contamination

BACKGROUND

The immunomodulating potential residing in cow's milk proteins is currently receiving increasing attention because of growing interest in functional foods and the complex problem of cow's milk allergy. One of the major cow's milk allergens, whey protein beta-lactoglobulin, has previously been shown to mediate cellular activation in both human and murine immune cells.

OBJECTIVE

We examined the response to different beta-lactoglobulin preparations in naive immune cells.

METHODS

Splenocytes and cells from mesenteric lymph nodes derived from BALB/c mice bred and maintained on a milk-free diet were cultured in vitro with different beta-lactoglobulin preparations. Cell proliferation, cytokine production, and increases in intracellular glutathione were used as cellular activation markers. Moreover, the effect of beta-lactoglobulin on cytokine production in murine bone-marrow-derived dendritic cells was examined.

RESULTS

We observed that some commercial beta-lactoglobulin preparations induced pronounced proliferation of both spleen cells and cells from mesenteric lymph nodes; production of TNF-alpha, IL-6, IL-1beta, and IL-10; and an increased level of intracellular glutathione in spleen cell cultures. Furthermore, TNF-alpha, IL-6, IL-1beta, and IL-10 production was induced in murine bone-marrow-derived dendritic cells. Purification of beta-lactoglobulin from raw milk using nondenaturating conditions, however, revealed that the beta-lactoglobulin per se did not possess the immunomodulatory activity. Eventually, the immunostimulatory effect was found to be caused by endotoxin contamination.

CONCLUSION

These results identify endotoxin as the main immunostimulatory component present in some commercial beta-lactoglobulin preparations. Moreover, the present study makes it evident that immunomodulatory effects attributed to beta-lactoglobulin need to be reassessed.

Allergen-specific T cell reactivity in cord blood: the influence of maternal cytokine production

BACKGROUND

Successful pregnancy is dependent upon T helper (Th)2-type-dominated immunological responsiveness in gestation-associated compartments.

OBJECTIVE

In our study we observed the influence of the maternal Th2-associated cytokine pattern on the naive fetal T cell phenotype and asked if circulating Th2 cytokines of atopic mothers affects the Th1/Th2 differentiation of the fetus.

METHODS

Cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) of the corresponding mothers were isolated. The proliferative response of CBMC and PBMC to Betalactoglobulin (BLG) was assessed by liquid scintillation counting. The cytokines interferon (IFN)-gamma, and interleukin (IL)-5, IL-10 and IL-13 in the cell culture supernatants were measured using the ELISA technique. We then defined two subgroups based on maternal levels of specific IgE against aeroallergens: sensitized mothers (MA(+)) and their neonates (NMA(+)) (n = 18) and non-sensitized mothers (MA(-)) and their neonates (NMA(-)) (n = 29).

RESULTS

Nearly all mothers (98%) and neonates (92%) had a positive proliferation response after stimulation with BLG (mean stimulation index (10-90 percentile): neonates: 7 (2-15); mothers 14 (5-29)). In supernatants of BLG-stimulated cell cultures, sensitized mothers showed a significantly lower IFN-gamma concentration in comparison to non-sensitized mothers (MA(+) = 25; MA(-) = 123 IU/L; P < 0,05), whereas the neonates did not differ significantly (NMA(+) = 306; NMA(-) = 224 IU/L; n. s.). Nor was any difference found in the IL-13 concentration between the two groups of sensitized and non-sensitized mothers (MA(+) = 48; MA(-) = 125 pg/mL; n. s.). CBMC of neonates with a sensitized mother showed significantly higher IL-13 concentrations in response to BLG than neonates of non-sensitized mothers (NMA(+) = 1442, NMA(-) 738 pg/mL; P < 0.05). The IL-5 and IL-10 concentrations did not differ significantly within the neonatal and the maternal subgroups.

CONCLUSIONS

Our data suggests that maternal sensitization to allergens is associated with the reduced maternal production of the Th2 antagonist IFN-gamma and elevated production of the Th2 cytokine IL-13 in the offspring.

Transplacental priming of the human immune system with environmental allergens can occur early in gestation

BACKGROUND

Allergen-specific T cells play an important role in the allergic immune response to various environmental allergens. In vitro studies have shown that T-cell responses to these allergens do occur prenatally. Some allergens (milk proteins) appear to lead more often to fetal T-cell priming than others (house dust mite allergen, ovalbumin, and birch and grass pollen allergens).

OBJECTIVE

We sought to determine the window of opportunity for prenatal T-cell priming with inhalant and nutritive allergens.

METHODS

The T-cell reactivity of cord blood cells derived through cordocentesis from unborn (n = 62) and term babies (n = 114) in response to inhalant allergens (birch pollen major allergen, recombinant Bet v 1, and timothy grass major allergen, recombinant Phl p 1) was investigated.

RESULTS

The results demonstrate that allergen-specific T-cell reactivity is as common in preterm as in term infants (Bet v 1, 8% and 5%, respectively; Phl p 1, 20% and 25%, respectively).

CONCLUSIONS

Our data support the hypothesis that differential handling of the allergenic proteins by the feto-placental barrier and possibly by antigen-presenting cells may directly modulate the ensuing T-cell immune response.