Tree-pollen allergy is efficiently treated by short-term immunotherapy (STI) with seven preseasonal injections of molecular standardized allergens

The efficacy and tolerance of short-term immunotherapy (STI) by seven preseasonal injections of tree-pollen allergens (ALK7 Frühblühermischung) was investigated in a double-blind, placebo-controlled, multicenter study with 111 rhinoconjunctivitis patients. Nasal and bronchial symptoms simultaneously analyzed, and nasal symptoms as a single end point, but not the overall score of nasal, bronchial, and conjunctival symptoms, showed a significantly lower increase with STI during birch-pollen exposure (both P=0.033, n=105, Mann-Whitney U-test). However, a selective analysis with patients from centers with high recruitment figures (n> or =10 patients, n=29 STI, n=32 placebo) showed a significantly lower increase of nasal, bronchial, and overall symptom score (STI 11.0 vs placebo 18.0, P=0.001, U-test). STI had equidirected effects on conjunctival, nasal, and bronchial symptoms analyzed as multiple end points, although conjunctival symptoms were not significantly different as a single end point. The seasonal increase in drug use was reduced by 62% in the STI group compared with placebo (P=0.032, t-test). Specific IgG4 increased only after STI (P<0.001); IgE was not significantly different. Eosinophil cationic protein remained unchanged with STI, but significantly increased with placebo in the pollen season (P=0.003). STI was well tolerated. In conclusion, STI was shown to be efficacious and safe for the treatment of patients with tree-pollen rhinoconjunctivitis.

Inhibition of interleukin-4 and interleukin-13 release from immunologically activated human basophils due to the actions of anti-allergic drugs

Human basophils have recently been shown to rapidly produce and release interleukin (IL-)4 and IL-13 as well as histamine and eicosanoids. Since both IL-4 and IL-13 can initiate and maintain late phase allergic reactions we addressed whether some widely used anti-allergic drugs can inhibit the anti-IgE induced release of these cytokines from enriched human basophils. Basophils were enriched (47-92% purity) by Ficoll density centrifugation followed by elutriation and negative selection of contaminating cells using immunomagnetic beads. Basophils were stimulated with sub-optimal dilutions of anti-IgE in the presence or absence of various drugs and the release of histamine and cytokines were measured after 30 min and 4 h, respectively. The beta-2 agonist salmeterol, the H1-receptor antagonist terfenadine and the phosphodiesterase inhibitor theophylline inhibited the release of IL-4 and IL-13 by more than 50% following 4 h of basophil stimulation with anti-IgE. These drugs also inhibited the release of histamine following 30 min stimulation, although with less efficacy than for IL-4 and IL-13. Short preincubation of basophils with salmeterol or terfenadine before stimulation gave rise to significantly greater inhibition of histamine release but had less effect on the inhibition of cytokine release. The effects of theophylline, however, were not significantly affected by preincubation of the cells with the drug. In contrast to the aforementioned drugs, salbutamol and cetirizine were ineffective at inhibiting both histamine and cytokine release from basophils. These results suggest that a number of anti-allergic drugs may mediate their effects, in part, in reducing late phase allergic responses due to their actions on IL-4 and IL-13 secretion from basophils.

[Pathophysiologic and immunologic mechanisms of contrast medium-induced anaphylactoid immediate hypersensitivity--an overview]

Since non-ionic radiocontrast media (RCM) have been introduced, the incidence of unwanted reactions has been significantly reduced in comparison to ionic compounds. However, acute anaphylactoid reactions with heterogenous symptoms within minutes after intravasal application are still a life-threatening risk of investigations with RCM. The present article summarizes the current view of the underlying pathomechanisms of such reactions.

A three-step procedure for the purification of human basophils from buffy coat blood

OBJECTIVE AND DESIGN

We report a method for basophil purification from buffy coats, which avoids positive selection of the cells and gives rise to good purity, yield and functional integrity of the cells.

SUBJECTS

Buffy coat blood (concentrated leukocyte fraction derived from 450 ml venipuncture donations) obtained from healthy blood donors (n = 51).

METHODS

Basophils were enriched by a three-step process starting with Ficoll density centrifugation (1.6 +/- 0.1% basophil purity) followed by counter current centrifugal elutriation (17.7 +/- 1.4% basophil purity). The final stage involved negative selection using Dynal immunomagnetic beads directed against CD2, CD14, CD16 and CD19 positive cell contaminants. Functional integrity of which was assessed by comparing the anti-IgE or calcium ionophore A23187 induced histamine release from basophils obtained from each enrichment step. Furthermore, basophil morphology was investigated using light and electron microscopy.

RESULTS

The final mean basophil purity of 67.3 +/- 1.4% with a yield of 3.5 +/- 0.5 x 10(6) basophils and a recovery of 21.8 +/- 2.4% was achieved. Net histamine release from basophils stimulated with optimal concentrations of anti-human IgE was 39.1 +/- 6.5% after Ficoll centrifugation, 41.6 +/- 7.7% following elutriation and 35.7 +/- 6.8% from the final purified fraction. Additionally, basophils enriched with our method showed intact morphology by electron microscopy and were functionally active to non-immunological stimulation.

CONCLUSIONS

These results compare favourably with previous studies, which have often required the use of positive selection via the Fc epsilon RI receptor, which may result in cell degranulation, or cell sorting, which cannot be applied to large cell numbers. Our method provides a reproducible technique for basophil enrichment when large numbers of functionally intact basophils are required.

Heterogeneity of signal transduction mechanisms in human basophils and human skin mast cells. II. Effects of 7-O-methyl-UCN-01, NPC 15437 and bryostatin 1 and 2, four protein kinase C-modulatory agents, on mediator release

Basophils and mast cells play a crucial role in immunological and allergic processes due to the release of inflammatory mediators such as histamine. It has been suggested for a long time that the histamine release (HR) from these cells is closely related to protein kinase (PKC) activity. However, the distinct role of PKC with its large variety of isozymes in different cell types and the actions of these isozymes in HR still remain unclear. Therefore, in the present study, we compared the effects of the two PKC inhibitors 7-O-methyl-UCN-01 (UCN-01-Me) and NPC 15437 as well as two PKC activators, bryostatin 1 and 2, on anti-IgE and Ca(2+)-ionophore-induced HR from human basophils and isolated human skin mast cells (HSMC). In both HSMC and basophils, anti-IgE-induced HR was inhibited by PKC inhibitor UCN-01-Me pre-incubation dose-dependently. In stark contrast, A23187-induced HR was unaffected by UCN-01-Me in both cell types. In our experiments, the inhibitory efficacy of the compound NPC 15437 on HR was much lower than that of UCN-01-Me and showed no statistical significance. Both bryostatins 1 and 2 produced good dose-dependent inhibition of HR from HSMC stimulated with anti-IgE, whereas HR from basophils was potentiated with these compounds. The same effects were observed with basophils stimulated with A23187, where potentiation of HR was up to fourfold of the control at the highest concentrations of bryostatins, while HSMC showed a slight decrease in HR compared to non-bryostatin-treated controls. Basophils and HSMC showed very clear differences in HR when directly stimulated with the bryostatins, since no HR was observed from HSMC while in basophils the HR increased up to 47% of total histamine at the highest concentrations of bryostatins (1 mumol/l). HR from basophils was observed to be strictly dose-dependent. The differences in the cell reactions of the two cell types incubated with these four compounds indicate distinct biochemical roles of PKC in the cascades leading to degranulation of the cells. Furthermore, the experiments with UCN-01-Me support the hypothesis of PKC-beta to play a substantial positive modulatory role for the degranulation of immunologically stimulated basophils.

Purified human peripheral blood basophils release interleukin-13 and preformed interleukin-4 following immunological activation

Recent studies have shown that human basophils, like mast cells, generate interleukin (IL)-4 following immunological activation and may thus participate in late-phase allergic and inflammatory processes. Here, we report the capacity of human basophils to release IL-13 within 24 h following stimulation with anti-IgE. Additionally, in 14 out of 31 experiments, we observed that basophils rapidly release performed IL-4 within 5-10 min, as well as newly generated IL-4, which was released 4 h following stimulation of the cells with anti-IgE. In contrast to the biphasic release of IL-4 from the cells, no preformed IL-13 was detected at earlier times (5-30 min). Preformed IL-4 and IL-4 and IL-13 generated de novo were also released after stimulation of the cells with IL-3; an enhanced production of these cytokines was observed using a combination of IL-3 and anti-IgE. We conclude from these data that, by releasing performed IL-4 and IL-4 and IL-13 generated de novo, human basophils may be centrally involved in the orchestration of allergic inflammation by providing a trigger to IL-4-mediated T helper 2 lymphocyte activation, B cell IgE switching, and increased vascular adhesion molecule expression.

Effects of basophil-priming and stimulating cytokines on histamine release from isolated human skin mast cells

Cell priming and stimulation of different cytokines (which include chemokines and growth factors) are typical features of human basophils. Recently, it has been shown that the macrophage chemotactic protein-1 (MCP-1), RANTES and macrophage inflammatory protein-1 alpha (MIP-1 alpha) are potent direct secretagogues for human basophils and that interleukin-3 (IL-3), IL-5 and granulocyte/macrophage colony-stimulating factor (GM-CSF) are priming factors for subsequent potentiation of mediator release from basophils induced by different stimuli. This observation may be clinically important for the activation and recruitment of inflammatory cells in different immune responses of the skin (e.g. late-phase reactions). The aim of the present study was to investigate whether cytokines and chemokines are also capable of priming or stimulating isolated human skin mast cells (SMC). SMC were either stimulated directly with the cytokines alone or preincubated with these factors for 10 min before being activated with suboptimal concentrations of anti-IgE, A23187 or substance P. IL-3, IL-5, GM-CSF, platelet factor-4 (PF-4), IL-8, MCP-1 and MIP-1 alpha (each at concentrations of 1 ng/ml to 1 microgram/ml, log steps) did not significantly modulate histamine release from SMC induced by the three different secretagogues. RANTES exhibited a weak but significant potentiating effect on IgE-mediated activation. Stem cell factor (SCF) as a positive control was able to prime mast cell histamine release strongly. In addition, PF-4, MCP-1, RANTES and MIP-1 alpha were incapable of inducing direct histamine release from SMC. In experiments with isolated human peripheral basophils, however, we observed potent Fc epsilon RI-mediated priming effects evoked through IL-3, IL-5 and GM-CSF. We conclude that SMC derived from healthy donors are not targets of (immuno)modulatory factors that prime or stimulate basophils.

Human basophils release interleukin-4 after stimulation with Schistosoma mansoni egg antigen

The elevated interleukin (IL)-4 and IgE production in Schistosoma mansoni infection seems to be induced essentially by the egg stage of the parasite. The underlying mechanism, however, is not known. Since basophils from human peripheral blood can produce IL-4, we asked, whether soluble S. mansoni egg antigens (SEA) would trigger basophils to release IL-4. Basophils from healthy human donors (n = 32) without prior history of schistosomiasis were incubated with SEA in the presence of IL-3. In all donors, IL-4 was produced at different concentrations. The IL-4 production was dependent on the dose of SEA, was correlated with the purity of the basophil preparation, and the IL-4 concentration in the culture supernatant was maximal 5 h after stimulation with SEA. In addition to its IL-4-stimulatory effect, SEA triggered basophils to degranulate, thereby releasing histamine and sulfidoleukotrienes. Stripping of receptor-bound IgE from basophils inhibited both SEA- and anti-IgE-induced, but not ionomycin-induced IL-4 production. Moreover, resensitization of stripped basophils with stripping supernatants or human serum restored SEA-induced IL-4 production. This suggests that IgE is involved in the mechanism of IL-4 induction by SEA. Since IL-4 is induced in basophils from nonexposed donors, basophils may play a role as an early source of IL-4 in S. mansoni infection.

Heterogeneity of human skin mast cells and human basophils. I. Pharmacological experiments with activators and inhibitors of protein kinase C

Skin mast cells and basophilic leukocytes are known as key elements of acute and subacute IgE-mediated immune responses of the skin. The present paper investigated pharmacological aspects of signal transduction pathways of both cell types using activators and inhibitors of protein kinase C (PKC). The nonselective inhibitor K252a suppressed Fc epsilon RI-mediated histamine release from basophils and skin mast cells dose-dependently with IC50 values of 0.01 and 0.28 mumol/l. However, preincubation of both cell populations with kinase inhibitors showing in vitro selectivity for PKC (Ro 31-7549, calphostin C, GF 109203X) revealed a distinct modulation of cell response: IgE-mediated mediator release was inhibited only in skin mast cells, whereas in experiments with basophils a concentration-dependent potentiation of exocytosis was observed. Further evidence for heterogenous biochemical signals following activation of both cell types derived from studies with the phorbol ester TPA. With respect to acute and late-phase IgE-mediated skin reactions, we suggest that distinct signal transduction mechanisms at the level of PKC (isozymes) in basophils and skin mast cells might reflect their functional heterogeneity.

[Abdominal variant of benign symmetrical Launois-Bensaude lipomatosis]

We report on a patient with an abdominal type of benign symmetrical Launois-Bensaude lipomatosis. New aspects of the pathogenesis of abnormal distribution of the fatty tissue are also discussed.

[The role of basophilic leukocytes in inflammatory skin diseases]

Basophilic leukocytes are effector cells of the peripheral blood. They have several morphological and functional characteristics in common with tissue mast cells, such as expression of the high-affinity IgE receptor (Fc epsilon RI) and a high content of histamine within their granules. Functional comparison of human basophils and human mast cells isolated from different tissues revealed marked heterogeneity of mediator release after incubation with different secretagogues. Owing to their wide range of surface receptors, their (pro)inflammatory mediators released after activation, their mobility, and their rapid turnover, basophils appear basically to be potent effector cells, which migrate transiently into the skin during IgE-mediated (and/or IgE-independent) inflammatory reactions. The present paper reviews recent findings on the possible role of basophils for different immune reactions of the skin. Inhibition of basophil (and/or mast cell) activity seems to be necessary for both effective prophylaxis and therapy of allergic and inflammatory skin diseases. To date, however, the pharmacological modulation of mediator release from basophils lacks potent clinically useful compounds that can suppress the cellular response, since mast cell stabilizers such as cromoglycate and nedocromil are not effective. With a view to the development of active compounds, further in vitro studies should focus on the mechanisms of cell activation.

Healing of chronic atopic dermatitis lesions in skin areas of paraplegia after trauma

A case of atopic dermatitis in a 12-year-old boy with spontaneous clearing of skin lesions in areas of paraplegia after trauma is reported. This observation might confirm the important pathogenetic role of neuropeptides in the development of atopic dermatitis.

Functional comparison of different histamine-containing IgE-receptor positive cells

The present study was performed to investigate the histamine-releasing activity of non-immunological stimuli on cultured mast cell lines in comparison to isolated skin mast cells and basophils as human therapeutic target cells. The ionophore A23187 induced a dose dependent histamine release from all cell populations (enzymatically isolated human skin mast cells, human peripheral basophils and rat basophilic leukemia cells, RBL-1 and RBL-2H3). The lectin concanavalin A and the tripeptide formyl-methionyl-leucyl-phenylalanine activated only basophils, while the neural mediator substance P and compound 48/80 were active only in experiments with skin mast cells. Activators of protein kinase C (different phorbol esters and the non-phorbol mezerein) induced direct histamine release only from basophils. The data provide further evidence for heterogeneity of mast cells and indicate different signal transduction mechanisms following non-immunological activation.

Direct effects of second-generation H1-receptor antagonists on the activation of human basophils

The present study was performed to investigate the putative suppressive effects of H1-receptor antagonists (HRA) of the second generation (astemizole (AS), cetirizine (CT), loratadine (LO), oxatomide (OX) and terfenadine (TF)) on the mediator release from human basophils activated by two classical stimuli. Anti-IgE-mediated histamine release was inhibited in a dose-dependent fashion by TF (maximum inhibitory value: 33.8 +/- 7.6%, 100 microM, n = 7), whereas the other HRA exhibited weaker activity. The anti-IgE-induced LTC4 production was strongly suppressed by TF, LO and OX (92.4 +/- 6.3%, 90.8 +/- 6.0% and 88.5 +/- 5.6%, 100 microM, n = 4-5), while AS was less active (56.4 +/- 4.1%, 100 microM, n = 5). Histamine release induced by incubation with grass pollen antigen (0.01%) was inhibited by TF (40.7 +/- 4.1%, 50 microM, n = 4), but the other HRA showed only low activity. The present findings suggest that some HRA might exhibit direct inhibitory effects on activation of IgE-receptor bearing cells.

Immunohistochemical studies with skin mast cells

Using different histochemical and immunohistochemical methods we demonstrate that isolated skin mast cells used for different pharmacological and biochemical studies exhibit the same staining pattern compared to skin mast cells in situ. Surface structures and enzyme content of the cells appear not to be influenced by the isolation technique. We also observed no differences in the staining pattern of mast cells in neurofibroma, a cutaneous disorder characterized by an increase of mast cell numbers.

Investigations with the selective PKC inhibitor chelerythrine on human basophils

Modulation of protein kinase C (PKC) activity in basophils (B) can influence IgE-mediated histamine release (HR). The present study investigated the effects of chelerythrine, which inhibits isolated PKC (IC50 0.7 microM), on different activation pathways in B. Fc epsilon RI-mediated HR was strongly inhibited by chelerythrine (86.5 +/- 5.4%, 5 microM, n = 11). TPA-induced mediator release was also suppressed: 77.1 +/- 8.5% inhibition (7.5 microM). HR due to non-immunological stimuli (A23187, FMLP) was strongly inhibited by chelerythrine. Previously, other selective PKC-inhibitors have been shown to potentiate IgE-mediated HR from B suggesting a negative modulatory role of PKC, whereas non-specific inhibitors such as staurosporine inhibited HR. Chelerythrine might therefore be less selective for PKC. This may be indicated by the fact that chelerythrine inhibits PKC at its catalytic domain, which is homologous with other protein kinases.

Control function of protein kinase C isozymes on leukotriene generation from human basophils?

Arachidonic acid metabolites generated from activated basophils and/or mast cells mediate different types of cutaneous inflammatory reactions. To clarify the mechanisms of leukotriene C4 (LTC4) production from human basophils, cells were purified from the peripheral blood by negative selection with immunobeads. The protein kinase C (PKC) activators 12-O-tetradecanoyl-phorbol-13-acetate, phorbol-12,13-dibutyrate and phorbol-12,13-didecanoate did not induce a significant LTC4 generation from human basophils in vitro, indicating that phorbol-ester-sensitive PKC isozymes are not involved in the mechanisms of arachidonic acid metabolism in these cells. However, selective PKC inhibitors (Ro 31-7549, ilmofosine, GF109203X, and calphostin C) potentiated the IgE-mediated LTC4 production in a dose-dependent fashion. We therefore suggest that PKC isozymes which are influenced by these inhibitors modulate the degree of LTC4 release after stimulation with anti-IgE antibodies.

Investigations on plasma levels of mast cell mediators in acute atopic dermatitis

Skin mast cells have been proposed to be involved in the pathogenesis of acute and chronic phases of atopic dermatitis (AD). The aim of the present study was to investigate the significance of different mast cell mediators during acute exacerbation of this frequent skin disease. Plasma levels from 19 patients with AD were screened for elevation of the mast cell-specific protease tryptase, the biogene amine histamine, and the arachidonic acid metabolite prostaglandin D2. None of the patients showed elevated plasma levels of these three mediators, whereas the mean serum IgE level was strongly elevated. We conclude that the investigated mediators are either only active on the cutaneous level or that other mediators are responsible for the development of the acute eczematous and pruritic skin reactions. Alternatively, the assays could have been insufficiently sensitive since some studies have demonstrated increased plasma histamine levels, e.g. after food challenge of such patients.

CGP 41251, a novel protein kinase inhibitor with in vitro selectivity for protein kinase C, strongly inhibits immunological activation of human skin mast cells and human basophils

The process of high-affinity IgE receptor (Fc epsilon RI)-mediated signal transduction in human basophils and mast cells is accompanied by activation of protein kinase C (PKC). The present study investigated the effects of a novel protein kinase inhibitor with in vitro selectivity for PKC (CGP 41251) in comparison with the potent but non-selective PKC inhibitor staurosporine on the activation of human peripheral basophilic leukocytes and enzymatically isolated human skin mast cells. CGP 41251 exerted strong concentration-dependent inhibitory effects on Fc epsilon RI-mediated histamine release from both cell populations. In addition, the IgE-mediated generation of arachidonic acid metabolites (leukotriene C4/D4 and prostaglandin E2) from human basophils was also significantly inhibited by this compound. Its action was not significantly different from the action of staurosporine. Direct activation of cellular PKC by the phorbol ester 12-o-tetradecanoyl-phorbol-13-acetate and subsequent histamine release from basophils was also inhibited by both compounds. CGP 41251 did not suppress N-formyl-met-leu-phe- or A23187-induced activation of basophils, whereas A23187-induced mediator release from human skin mast cells was inhibited in a concentration-dependent fashion. We conclude that an increase of in vitro selectivity for PKC does not significantly enhance inhibitory effects on immunological activation of histamine-containing cells. Moreover, nonimmunological pathways of signal transduction in basophils and mast cells appear to be mediated by distinct biochemical events.

Pharmacological investigations with different protein kinase C inhibitors on IgE-dependent and IgE-independent activation of human basophils

In the present study different selective inhibitors of the multifunctional serine/threonine kinase protein kinase C (PKC) were investigated on classical activation pathways of basophils in comparison to the nonselective protein kinase inhibitor staurosporine. The potent inhibitors Ro 31-7549, Ro 31-8220, calphostin C and ilmofosine (BM 41.440), which show selectivity for PKC in vitro, significantly potentiated Fc epsilon RI-mediated histamine release up to 50% vs. controls at concentrations > 10(-7) mumol/l but were without any intrinsic histamine releasing activity. Direct activation of cellular PKC by phorbol ester was suppressed by all compounds apart from ilmofosine at the same concentrations. We did not observe statistically significant effects of selective PKC inhibitors on exocytosis induced by the peptide formylmeth-leu-phe (FMLP) or the ionophore A23187, whereas staurosporine potentiated the FMLP-induced histamine release in a dose-dependent fashion: maximum potentiation was 63.5 +/- 8.9% vs. control at 1 mumol/l (n = 4). The findings suggest that PKC exhibits differential functions during biochemical events of stimulus-secretion coupling in human basophils supposedly by its distinct subtypes. With respect to the present data, TPA-induced and IgE-mediated signals are not closely correlated.

Influence of protein kinase C activation on basophils from patients with atopic dermatitis in comparison with nonatopic controls

Protein kinase C (PKC) is suggested to be important for signal transduction of histamine-containing cells. The present study investigated the putative role of PKC in enhanced mediator release of basophils in atopic dermatitis (AD). Basophils were isolated from patients with severe AD (mean serum IgE level of 5,165 U/ml) and from healthy controls, and the effects of potent activators of PKC on histamine release were studied. The phorbol esters 12-o-tetradecanoyl-phorbol-13-acetate and phorbol-12,13-dibutyrate and the nonphorbol mezerein induced a dose-dependent mediator release, which was significantly lower in 'atopic' basophils at concentrations > or = 1 microM. Recently, PKC levels have been shown to be lowered in atopic leukocytes compared to cells from healthy controls. The lowered response of PKC towards direct activation and lowered PKC levels may be due to high serum IgE levels and allergen exposure in vivo with subsequent down-regulation of different key elements of signal transduction.