Biomedical subjects

M Schlaak

Publications and source records attributed to M Schlaak.

At least 19 recordsLinked to original sources

PubMed2001

Angiotensin-converting enzyme (ACE) gene polymorphisms and familial occurrence of sarcoidosis.

OBJECTIVES: The aim of this study was to test for genetic linkage and association between polymorphisms of the angiotensin-converting enzyme (ACE) gene and familial occurrence of sarcoidosis. DESIGN, SETTING AND SUBJECTS: German families with more than one member suffering from sarcoidosis were contacted and a DNA bank was established. Sixty-two families (140 patients, 77 females and 63 males, and 104 unaffected relatives) were genotyped for the ACE gene insertion/deletion (I/D) polymorphism and for two flanking variable sites (ACE A-5466C and ACE 4656(CT)2/3). As controls, 100 DNAs from unrelated resident Caucasians (50 females, 50 males) were analysed. ACE allele and genotype frequencies were determined, and parametric linkage and affected sib pair analyses and transmission disequilibrium tests were performed. RESULTS: There was a striking over-representation of the ACE I/D genotype DD in patients with sarcoidosis and their families as compared with controls of the study and well founded genotype frequencies from the literature. The same was evident for the accompanying genotypes CC and 2,2 of the flanking polymorphisms. Linkage between the segregation of ACE alleles and the disorder within families was clearly excluded for simple models of inheritance. However, there was a suggestive but not significant (P = 0.06) excess of allele sharing amongst affected siblings. There was no transmission disequilibrium for any ACE allele or haplotype. CONCLUSIONS: ACE is involved in the pathogenesis of sarcoidosis, but the ACE polymorphisms are not an inherited main cause of the disease. They are more likely to modify the development of the disorder, and the ACE I/D genotype DD might be a promoter to clinical manifestation.

Adult↗

PubMed2000

Analysis of differentially regulated mRNAs in peripheral blood monocytes of berylliosis patients after in vitro stimulation.

In berylliosis and other granulomatous diseases the macrophage is regarded as effector cell in granuloma formation. However, little is known about granuloma-associated regulation of genes in these cells. Differential display reverse transcription polymerase chain reaction (DDRT-PCR) is an attractive method for detection of differentially expressed genes. Since DDRT-PCR requires a comparably low quantity of RNA, its application to rare and limited amounts of clinical samples is convenient. In the present study we applied DDRT-PCR in a multiple and complex comparison of expressed sequence tags induced in response to various granuloma-associated and control stimuli. Since we are interested in granuloma-restricted changes, we tested peripheral blood monocytes from berylliosis patients by DDRT-PCR stimulated with up to nine different stimuli, including BeSO4, the causal agent of berylliosis. Comparison of a total of 1663 sequence tags in four berylliosis patients revealed a mean of 32.5-37.4% differentially regulated sequence tags in peripheral blood monocytes of berylliosis patients, caused by stimuli including beryllium or Mycobacterium tuberculosis and control stimuli such as Latex or Zymosan. In 7.7-28.0% of the analyzed sequence tags we detected a differential regulation restricted to the presence of granuloma-associated stimuli BeSO4, HgS, LiCO3, NiSO4, lipopolysaccharide, and/or heat killed M. tuberculosis; 1.4-12.3% were induced by more than one granuloma-associated stimulus. Alterations associated with BeSO4 and one of the named stimuli were detected in 1.4-4.5%. An exclusive association with BeSO4 was found in 2.6-5.7% of the analyzed sequence tags.

Adult↗

PubMed2000

Accessory function and costimulatory molecule expression of alveolar macrophages in patients with pulmonary tuberculosis.

An effective immune response against M. tuberculosis requires a coordinated interaction of alveolar macrophages (AM) and lymphocytes. Secondary signals, such as accessory function (AF) of antigen presenting cells and interaction of costimulatory molecules are also important for T cell activation. In the present study we determined the AF and the expression of CD11a, CD54, CD58, CD80, CD86 and HLA-DR costimulatory molecules by AMs lavaged from patients with pulmonary tuberculosis and controls. We hypothesized that alterations in AF and costimulatory molecule expression may influence the presentation of tuberculosis. Therefore these parameters were also correlated with the radiographic extension of the disease. AMs of patients with tuberculosis exhibited an increased AF and a significantly increased expression of co-stimulatory molecules compared with controls. Furthermore, we observed that the expression of CD54 (ICAM-1) decreased with the course of the disease. We conclude that the infection by M. tuberculosis results in an increased AF of AMs and the activity of AMs remains uninfluenced by the extension of the disease. Clear-cut changes of patterns of costimulatory molecule expression by AMs could not be observed with the progression of tuberculosis.

Antigens, CD↗

PubMed2000

Serum level of soluble tumour necrosis factor receptor II (75 kDa) indicates inflammatory activity of sarcoidosis.

OBJECTIVES: Tumour necrosis factor alpha (TNFalpha) is a key cytokine involved in granuloma formation of sarcoidosis. Since soluble TNF receptors (sTNF-R) are known to inhibit TNF effects, we were interested in whether they are elevated in the serum of sarcoidosis patients. METHODS: We determined serum levels of sTNF-R I (55 kDa) and sTNF-R II (75 kDa) in 49 patients with sarcoidosis and 22 controls. The clinical course of the disease was re-evaluated in a follow-up after (mean +/- SE) 6.8 +/- 6.6 months. RESULTS: sTNF-R I (3.1 +/- 1.1 ng mL-1, P < 0.05) and sTNF-R II (5.5 +/- 2.7 ng mL-1, P < 0.0005) were significantly elevated in sarcoidosis compared with controls (2.4 +/- 0.7 and 3.0 +/- 1.3 ng mL-1, respectively). Interestingly, both sTNF receptors were significantly higher in the serum of patients with active compared with inactive sarcoidosis (P < 0.005 and P < 0.0005, respectively). Furthermore, serum sTNF-R II levels were significantly higher in sarcoidosis patients with advanced radiological types II and III. In 10 patients, serum sTNF-R levels were obtained before and after systemic corticosteroid therapy and we observed a significant decrease of sTNF-R II (P < 0.02), whereas sTNF-R I levels were not reduced significantly. CONCLUSIONS: Both types of sTNF receptors are elevated in the serum of sarcoidosis patients with active disease, but only the sTNF-R II seems to be useful for monitoring the inflammatory activity of the disease.

Adrenal Cortex Hormones↗

PubMed2000

Familial sarcoidosis is linked to the major histocompatibility complex region.

Sarcoidosis is a systemic granulomatous disorder associated with high CD4+ cell activity, but no pathogen is detectable. Clustering in families occurs, and the existence of a genetic predisposition to sarcoidosis is widely accepted. The major histocompatibility complex (MHC) is believed to contribute to this susceptibility. Many studies testing this hypothesis have produced conflicting results. We have genotyped 122 affected siblings from 55 families for seven DNA polymorphisms that flank and cover the MHC region on chromosome 6, and for HLA-DPB1, a candidate gene for granulomatous disorders. Multipoint nonparametric linkage (NPL) analysis showed linkage (NPL score > 2.5; p < 0.006) for the entire MHC region with a maximum NPL score of 3.2 (p = 0.0008) at marker locus D6S1666 in the Class III gene cluster. There was a significant excess of marker haplotype sharing among affected siblings. However, the frequency of HLA-DPB1 alleles on 104 shared chromosomes did not differ from that of a control group of founders from the family panel. Transmission disequilibrium was found for allele DPB1*0201, but only nine families contributed to this result. We conclude that genes of the MHC are involved in the genetic predisposition to sarcoidosis, but HLA-DPB1 alone does not sufficiently explain this fact.

Alleles↗

PubMed2000

Trichostatin A modulates expression of p21waf1/cip1, Bcl-xL, ID1, ID2, ID3, CRAB2, GATA-2, hsp86 and TFIID/TAFII31 mRNA in human lung adenocarcinoma cells.

Lung adenocarcinoma cells treated for 16 h with trichostatin A (TSA), an inhibitor of histone deacetylases, and untreated cells were analyzed with respect to differential gene expression. Complex hybridization of cDNA arrays revealed repression of Bcl-xL, CRAB2 and TFIID/TAFII31 as well as induction of p21waf1/cip1, GATA-2, hsp86, ID1, ID2 and ID3 mRNA expression, which could be verified by Northern blotting. ID2 induction was further confirmed by Taqman realtime quantitative RT-PCR. The described alterations of gene expression due to TSA renders the lung adenocarcinoma cells susceptible to induction of apoptosis.

Adenocarcinoma↗

PubMed2000

Trichostatin A-mediated regulation of gene expression and protein kinase activities: reprogramming tumor cells for ribotoxic stress-induced apoptosis.

Recently we described a new signal transduction-based tumor therapeutic strategy involving first sensitization of tumor cells by trichostatin A (TSA), an inhibitor of histone deacetylation, and thereafter efficient apoptotic triggering by ribotoxic agents, which activate stress-activated protein kinases. In the present work we investigate the molecular basis of the sensitization step in this therapeutic model system and describe TSA-induced changes in mRNA and protein expression of several candidate genes identified previously by complex hybridization. Furthermore, activities of 15 different protein kinases were followed after TSA application, using a new filter-based technique (PhosphoSpots-Assay). The obtained data suggest that TSA induces pro-apoptotic genes like ID1, ID2, ID3, and down-regulates anti-apoptotic genes like Hsp27 and Bcl-xL, thereby shifting the cellular equilibrium from life to death. Furthermore, activities of calcium/calmodulin-dependent kinase II and protein kinase C, which have been assigned pro-apoptotic function in other systems, are induced.

Apoptosis↗

PubMed2000

Human alveolar epithelial cells type II are capable of regulating T-cell activity.

Alveolar epithelial cells type II (AEC-II) express MHC class II on their surface, an important prerequisite for antigen presentation. However, accessory signals are required for an efficient T-cell activation. We therefore isolated AEC-II from tumor-free sections of human lungs obtained by lobectomy/pneumectomy and purified the cells by magnetic-activated cell sorting. Furthermore, we tested the expression of CD54, CD58, CD80, and CD86 on AEC-II and evaluated their accessory function (AF) in cell culture using a coculture of interleukin-2 (IL-2), releasing Jurkat cells and AEC-II. An increased AF is documented by an elevated IL-2 release and expressed as accessory index (AI). In 33 experiments the AF of AEC-II proved to be highly variable. AI ranged between 0.3 and 17.1 with a median of 1.4 (0.3-17.1). Forty-four percent (4-77) of the AEC-II expressed HLA-DR, 44% (12-89%) of the cells expressed CD58, and CD54 was expressed by 55% (16-89%). AEC-II also expressed CD80 and CD86 (38% [0-77%] and 40% [4-68%], respectively). Interestingly, AEC-II released high levels of TGF beta (1730 pg/mL [771-5876]) and the accessory index could be increased (approximately 2-fold) by the addition of neutralizing anti-TGF beta antibodies or radiation. Thus, type II alveolar cells express costimulatory molecules and are able to deliver costimulatory signals for T cells, providing evidence that AEC-II are able to act as antigen-presenting and immunoregulatory cells of the lung. Additionally, the accessory function of AEC-II is under the control of endogenously released TGF beta.

Antigen-Presenting Cells↗

PubMed2000

In vitro release of interleukin-15 by broncho-alveolar lavage cells and peripheral blood mononuclear cells from patients with different lung diseases.

IL-15 shares several biological activities with IL-2 and uses the b and g chain of the IL-2 receptor. In addition to its T-cell stimulating capacity, IL-15 exhibits regulatory properties on macrophage proinflammatory cytokine release. IL-15 is released by non-lymphoid cells, e.g. muscle cells, fibroblasts and monocytes/macrophages. In many lung diseases alveolar macrophages (AM) are activated and release pro- inflammatory cytokines. We asked whether IL-15 is released ex vivo by AM and peripheral blood mononuclear cells (PBMC) from patients with inactive sarcoidosis (PSi), active sarcoidosis (PSa), tuberculosis (TB), hypersensitivity pneumonitis (HSP), cryptogenic fibrosing alveolitis (CFA) and pneumonia (PN). Additionally, we examined the kinetics of the IL-15 release of these cells. During 24 hours of culture, AM from controls (CO) released 3.8 +/- 1.9 pg/ml (mean +/- SD) of IL-15, which was significantly lower than in most of the patient groups (PSa: 8.7 +/- 3.9 pg/ml, TB: 8.4 +/- 1.9 pg/ml, CFA: 5.7 +/- 1.5 pg/ml, and PN: 7. 8 +/- 2.6 pg/ml) except PSi (4.0 +/- 2.6 pg/ml) and HSP (9.3 +/- 9.5 pg/ml). PBMC from patients with PSa released significantly more IL-15 than PBMC from CO (10.8 +/- 8.9 pg/ml versus 6.9 +/- 2.2 pg/ml) whereas PBMC IL-15 release of the other groups did not differ from CO (TB: 5.7 +/- 1.4 pg/ml; CFA: 4.6 +/- 1.6 pg/ml; HSP: 4.9 +/- 3.8 pg/ml). Kinetic studies revealed a minor peak after 5 hours and a major peak from 12 hours to 35 hours for AM and PBMC. In summary, AM from all patient groups but the PSi and the HSP group released increased levels of IL-15, although the total amount of this cytokine is very low.

Alveolitis, Extrinsic Allergic↗

PubMed2000

Effect of proinflammatory cytokines on interleukin-8 mRNA expression and protein production by isolated human alveolar epithelial cells type II in primary culture.

Alveolar epithelial cells type II (AEC-II) are ideally situated to regulate the recruitment and activation of different types of cells through the production of chemokines in response to inflammatory stimulation from the alveolar space. We hypothesized that these cells are important producers of interleukin-8 (IL-8) in the lung. This lead us to investigate the capacity of isolated human AEC-II cells to release IL-8 and whether this IL-8 release is regulated by proinflammatory cytokines, i.e. IL-1 beta, TNF-alpha and IFN-gamma. We isolated AEC-II from tumor-free sections of human lungs obtained by pneumectomy and purified the cells by magnetic activated cell sorting. For control experiments the AEC-II-like cell line A549 was used. IL-8 concentration was measured by ELISA in supernatants of unstimulated and LPS-, IL-1 beta-, TNF-alpha- and IFN-gamma- stimulated cells. IL-8 mRNA expression was evaluated by RT-PCR. Spontaneous IL-8 mRNA expression and protein secretion by AEC-II were significantly higher in comparison with A549 cells. TNF-alpha increased both IL-8 mRNA expression and protein production, whereas IL-1 beta slightly increased IL-8 release but did not change mRNA expression in AEC-II. LPS and IFN-gamma did not influence IL-8 expression in AEC-II and A549 cells. These results show considerable differences between A549 cell and AEC-II. The latter are capable of producing IL-8 under the control of proinflammatory cytokines. Our findings demonstrate that the modulation of IL-8 release in AEC-II may have an important impact on the immunoreactivity of these cells during pulmonary inflammation in vivo.

Cells, Cultured↗

PubMed1999

Purification of morphologically and functionally intact human basophils to near homogeneity.

Certain studies on basophils require highly purified functionally intact cell preparations. Here, a three-step procedure is described that meets these requirements. The procedure consists of a Ficoll density gradient step, counterflow elutriation and negative selection by magnetic cell sorting (MACS). The mean purity of basophils obtained from 30 donors was 97.6+/-3.96% with a viability of 99.6+/-0.83%. The recovery rate was 49.7+/-15.6%. The cells had a normal morphological appearance as assessed by May-Grünwald-stained cytospins and were functionally intact as shown by their unaltered capacity to release histamine and interleukin 4 (IL-4) following immunological activation. This procedure is a clear improvement over currently available techniques and should facilitate future investigations on basophils.

Basophils↗

PubMed1999

Lymphocyte transformation test for the evaluation of adverse effects of antituberculous drugs.

The usefulness of the lymphocyte transformation test (LTT) for the analysis of adverse reactions to antituberculous drugs was evaluated. - The LTT was performed with isoniazid and rifampicin in 15 tuberculosis and 2 MOTT (Mycobacteria other than tuberculosis)-infection patients who suffered drug reactions, in 23 patients without any adverse reactions, in 7 controls previously exposed to antituberculous drugs, and in 14 controls who had never been exposed. 4/15 of the hepatotoxic reactions only showed a positive LTT with rifampicin, 3/15 only with isoniazid, and in 8/15 the LTT was negative. In an anaphylactoid shock reaction the LTT was extremely exaggerated for both rifampicin and isoniazid. In patients without any side effects only one slightly increased LTT due to isoniazid was observed. Two healthy controls with previous contact to these drugs showed a positive LTT for isoniazid, one of those with both rifampicin and isoniazid. The LTT was negative in all control persons without any former contact to antituberculous medications. In most cases hepatotoxicity seems to be a pure toxic reaction without the participation of cellular immune mechanisms. LTT can be useful for identifying the drug responsible for immunological side effects.

Adult↗

PubMed1999

Dietary lectins can induce in vitro release of IL-4 and IL-13 from human basophils.

Dietary lectins, present in beans and other edible plant products, pose a potential threat to consumers due to their capacity to induce histamine release from basophils. In this study, we analyzed the capacity of 16 common, in particular dietary, lectins to induce human basophils to secrete IL-4 and IL-13, the key promoters of Th2 responses and IgE synthesis. Several of the lectins, especially concanavalin A, lentil lectin, phytohemagglutinin, Pisum sativum agglutinin and Sambucus nigra agglutinin, triggered basophils to release IL-4 at concentrations of up to 1 ng/10(6) basophils. Lectins with high IL-4-inducing capacity also stimulated the release of IL-13 and histamine. Lectin-induced IL-4 and IL-13 release reached a maximum after 4-6 h and more than 18 h, respectively. Affinoblotting revealed that lectins with the capacity to induce mediator release bind to IgE, suggesting IgE binding as initial step of signal generation. In conclusion, several dietary lectins can trigger human basophils to release IL-4 and IL-13. Since lectins can enter the circulation after oral uptake, they might play a role in inducing the so-called early IL-4 required to switch the immune response towards a Th2 response and type I allergy.

Basophils↗

PubMed1999

Expression of tumour necrosis factor receptors (CD120a and CD120b) on bronchoalveolar cells.

It is generally accepted that physiological modulators for tumour necrosis factor (TNF) are present in a variety of body fluids including serum. Among these modulators are soluble TNF receptors (TNF-R) that are cleaved from the extracellular domain of the TNF-Rs. Two receptors of different structures with molecular weights of 55 kDa (CD120a) and 75 kDa (CD120b) are known to be expressed on monocytes, lymphocytes, granulocytes and other cells of peripheral blood. The aim of our study was to determine the expression of CD120a and CD120b on bronchoalveolar lavage cells (BAL cells). BAL cells of 14 patients with different pulmonary disorders were stained with anti-CD120a and anti-CD120b monoclonal antibodies and were differentiated by FACS analysis. Both TNF-Rs are expressed on monocytes, macrophages, lymphocytes and granulocytes of the BAL. Although the relation of CD120a to CD120b is individual for a given cell type and an individual patient, strict correlations between both receptors were observed for BAL monocytes and alveolar macrophages. CD120a are expressed on 29.7% of alveolar macrophages; similar data were obtained for CD120b. 24.3% of the BAL monocytes were positive for CD120a and 25.5% for CD120b. 4.1% of the BAL lymphocytes were positive for CD120a whereas the percentage of CD120b positive BAL lymphocytes was approximately six times greater. Analysis of BAL granulocytes revealed 21.2% cells positive for CD120a and 11.6% for CD120b. In contrast to the BAL cells named above there was no positive correlation between CD120a and CD120b expression on BAL lymphocytes and granulocytes. We were able to show that TNF-Rs of BAL cells, like those of blood cells, are shedded in vitro after incubation with or without lipopolysaccharide (LPS), detected as TNFalpha-inhibitor activity in cell culture supernatant. In conclusion, BAL cells express and shed TNF-Rs, as is known for cells of other body compartments.

Antibodies, Monoclonal↗

PubMed1999

Polymorphisms at position -308 in the promoter region of the TNF-alpha and in the first intron of the TNF-beta genes and spontaneous and lipopolysaccharide-induced TNF-alpha release in sarcoidosis.

TNF-alpha is a potent pro-inflammatory cytokine. Previous studies have proved that biallelic polymorphisms in the TNF-alpha (-308, TNFA) and TNF-beta genes (intron 1, TNFB) influence TNF-alpha production. In sarcoidosis, a chronic granulomatous disease, as a result of an unknown in vivo activation bronchoalveolar lavage (BAL) cells release high amounts of TNF-alpha, spontaneously and after in vitro stimulation. Thus, sarcoidosis could serve as a model to test the in vivo effect of TNF gene polymorphisms. We determined the TNFA and TNFB polymorphisms of 44 patients with sarcoidosis and found the following allele frequencies: 0.80, 0.20, 0.38 and 0.62 for TNFA1, TNFA2, TNFB1 and TNFB2, respectively. To examine the in vivo effect of the named polymorphisms on the TNF-alpha production, the spontaneous and LPS-induced TNF-alpha release of BAL cells and peripheral blood mononuclear cells were also determined in patients with sarcoidosis. Statistical analysis did not reveal any significant difference between sarcoidosis patients with different genotypes. The results show that TNFA and TNFB polymorphisms do not determine the level of TNF-alpha release of mononuclear cells activated during the course of sarcoid inflammation.

Alleles↗

PubMed1999

Pharmacological modulation of the IFNgamma-induced accessory function of alveolar macrophages and peripheral blood monocytes.

OBJECTIVE AND DESIGN: Although alveolar macrophages (AM) are poor accessory cells, alveolar macrophages of patients with sarcoidosis or tuberculosis show an elevated accessory function indicating that the accessory function (AF) of AM can be upregulated. MATERIALS AND METHODS: We examined whether the AF of AM and peripheral blood monocytes (PBM) can be increased by interferon-gamma (IFNgamma) and whether immunomodulating drugs like cyclosporine A, cyclophosphamide, dexamethasone, and ambroxol are able to modulate the accessory function and the expression of accessory molecules. RESULTS: IFNgamma increased the AF of AM and PBM up to 309 +/- 122% and 152 +/- 25%, respectively (p < 0.02, unstimulated control = 100%, in all cases). In alveolar macrophages this increase is most efficiently prevented by cyclosporine A (31 +/- 13%), followed by cyclophosphamide (64 +/- 20%) and dexamethasone (66 +/- 20%). In monocytes the IFNgamma-induced increase in accessory function is prevented only by cyclosporine A (17 +/- 7%) and dexamethasone (59 +/- 9%). Cyclosporine A was also the most effective drug downregulating the expression of accessory molecules (CD54, CD58, CD80 and CD86). CONCLUSIONS: In summary, the accessory function of alveolar macrophages and monocytes is upregulated by IFNgamma and can be controled by immunomodulating drugs.

Aged↗

PubMed1999

Analysis of differentially regulated mRNAs in monocytic cells induced by in vitro stimulation.

Macrophages are known to be effector cells in several granulomatous disorders. However, little is known about granuloma-associated up- or downregulation of genes in these cells. Differential display reverse transcription polymerase chain reaction (DDRT-PCR) is an attractive method for the detection of differentially expressed genes. Although this method entails a number of drawbacks, its application to rare and limited amounts of clinical samples is still convenient. In this study, we introduce a screening procedure for detecting differentially regulated sequence tags in samples of patients suffering from granulomatous diseases. We applied DDRT-PCR in a multiple and complex comparison of expressed sequence tags in response to various granuloma-associated stimuli. The histiocytic cell line U937 was used as a model. The cells had been stimulated with granuloma-associated agents such as Mycobacterium tuberculosis, BeSO4, lipopolysaccharide, or HgS and unspecific stimuli such as phorbol myristate acetate, phytohemagglutinin, Zymosan, and Latex. Comparative analysis of 2237 sequence tags obtained from 55 primer combinations revealed 22.4% differentially amplified PCR products. Notably, only 8.0% of the differentially expressed sequence tags showed an association restricted to in vitro cultivation in the presence of M. tuberculosis, lipopolysaccharide, BeSO4, and/or HgS, while 1.0-1.9% of the tags were altered exclusively as a consequence of stimulation with one of the granuloma-associated agents. Our data provide evidence that this strategy may function as a preselection for appropriate primer combinations to discover sequence tags which could be specifically associated with granulomatous disorders. This approach could shorten laborious screening, save consumption of valuable and rare samples, and could reduce the number of false-positive results.

Cell Line↗

PubMed1999

Monitoring allergen immunotherapy of pollen-allergic patients: the ratio of allergen-specific IgG4 to IgG1 correlates with clinical outcome.

BACKGROUND: Although allergen immunotherapy has been established as a treatment of type I allergy back in 1911, until now the underlying mechanisms have not been fully understood, nor are there any parameters which would allow one to monitor an ongoing treatment or to assess therapeutic success in the meantime. OBJECTIVE: We wanted to define allergen-specific parameters that change due to treatment in correlation with the clinical outcome. METHODS: We conducted a controlled study with grass pollen-allergic children and compared allergen-specific antibody titres before and 1 year after the onset of immunotherapy in contrast with untreated allergic and healthy children. Two recombinant forms of the major allergen group V of Phleum pratense (Phl p 5) served as model allergens. RESULTS: No change in IgE levels and no significant reduction of skin prick test (SPT) reactivity were seen. On the other hand, a significant reduction of symptom scores in the treated group and a significant rise in allergen-specific IgG1, IgG2 and IgG4 due to the treatment could be observed, but in neither case could we establish a correlation between the increasing amounts of the single antibody classes and the reduction of symptom scores. But most interestingly, when comparing the ratio of IgG4 to IgG1 with the symptom scores, we found significant correlations. Nevertheless, treated allergic patients still differ considerably from healthy controls as nonatopics have hardly any measurable allergen-specific IgG antibodies and no IgE antibodies at all. CONCLUSION: The ratio of IgG4 to IgG1 can serve as a valuable parameter that allows us to assess the success of immunotherapy already 1 year after the onset. The increase of specific IgG1 in relation to IgG4 during treatment reflects a possible influence of this subclass on the induction of tolerance towards allergens.

Allergens↗