P38 mitogen-activated protein kinase signal transduction in the diagnosis and follow up of immunotherapy of wasp venom allergy

[Basophil activation test to follow-up of patients treated with hymenoptera venom immunotherapy: a review of current evidence]

Hymenoptera venom immunotherapy (HVI) is a long-term effective treatment to avoid new systemic reactions in patients with Hymenoptera allergy. The sting challenge test is considered the gold standard to confirm the tolerance. However, the use of this technique is not generalized in clinical practice, being the basophil activation test (BAT), which functionally explores allergen response, an alternative that does not entail any of the provocation risks associated with the sting challenge test. This study reviews the publications that used the BAT to follow up and evaluate the success of the HVI. Studies assessing the changes between a baseline BAT before the start and BATs performed between the starting and maintenance phases of the HVI were selected. Ten articles were found, comprising information from 167 patients, of which 29% used the sting challenge test. The studies concluded the importance of evaluating the responses with submaximal allergen concentrations, which reflect basophil sensitivity, to monitor the HVI using the BAT. It was also observed that changes in the maximum response (reactivity) could not reflect the clinical status of tolerance, particularly in the initial phases of HVI.

Intermittent Hypoxia on the Attenuation of Induced Nasal Allergy and Allergic Asthma by MAPK Signaling Pathway Downregulation in a Mice Animal Model

Intermittent hypoxia (IH) has been an issue of considerable research in recent years and triggers a bewildering array of both detrimental and beneficial effects in several physiological systems. However, the mechanisms leading to the effect are not yet clear. Consequently, we investigated the effects of IH on allergen-induced allergic asthma via the mitogen-activated protein kinase (MAPK) signaling pathway. Forty BALB/c mice were dived into four groups. We evaluated the influence of IH on the cell signaling system of the airway during the allergen-induced challenge in an animal model, especially through the MAPK (mitogen-activated protein kinase) pathway. The protein concentrations of p-ERK/ERK, p-JNK/JNK, p-p38/p38, and pMEK/MEK were significantly reduced in the allergen-induced+IH group, compared to the allergen-induced group (p-value < 0.05 as considered statistically significant). The number of eosinophils, neutrophils, macrophages, and lymphocytes in the bronchoalveolar lavage fluid and Dp (Dermatophagoides pteronyssinus)-specific IgG2a and interleukins 4, 5, 13, and 17 were significantly reduced in the Dp+IH group, compared to the Dp group. These findings suggest that the MAPK pathway might be associated with the beneficial effect of IH on the attenuation of allergic response in an allergen-induced mouse model.

Flow Cytometric Allergy Diagnosis: Basophil Activation Techniques

The basis of flow cytometric allergy diagnosis is the quantification of changes in the expression of basophilic surface membrane markers (Ebo et al., Clin Exp Allergy 34: 332-339, 2004). Upon encountering specific allergens recognized by surface receptor FcεRI-bound IgE, basophils not only secrete and generate quantifiable bioactive mediators but also upregulate the expression of different markers (e.g., CD63, CD203c) which can be detected by multicolor flow cytometry using specific monoclonal antibodies (Ebo et al., Cytometry B Clin Cytom 74: 201-210, 2008). Here, we describe two flow cytometry-based protocols which allow the detection of surface marker activation (Method 1) and changes in intragranular histamine (Method 2), both reflecting different facets of basophil activation.

Sequential allergen desensitization of basophils is non-specific and may involve p38 MAPK

BACKGROUND

Sequential allergen desensitization provides temporary tolerance for allergic patients. We adapted a clinical protocol to desensitize human blood basophils ex vivo and investigated the mechanism and allergen specificity.

METHODS

We included 28 adult, grass allergic subjects. The optimal, activating allergen concentration was determined by measuring activated CD63(+) CD193(+) SS(Low) basophils in a basophil activation test with 8 log-dilutions of grass allergen. Basophils in whole blood were desensitized by incubation with twofold to 2.5-fold increasing allergen doses in 10 steps starting at 1 : 1000 of the optimal dose. Involvement of p38 mitogen-activated protein kinase (MAPK) was assessed after 3 min of allergen stimulation (n = 7). Allergen specificity was investigated by desensitizing cells from multi-allergic subjects with grass allergen and challenging with optimal doses of grass, birch, recombinant house dust mite (rDer p2) allergen or anti-IgE (n = 10).

RESULTS

Desensitization reduced the fraction of blood basophils responding to challenge with an optimal allergen dose from a median (IQR) 81.0% (66.3-88.8) to 35.4% (19.8-47.1, P < 0.0001). CD63 MFI expression was reduced from 68 248 (29 336-92 001) to 30 496 (14 046-46 179, P < 0.0001). Basophils from multi-allergic subjects were desensitized with grass allergen. Challenge with grass allergen resulted in 39.6% activation (15.8-58.3). An unrelated challenge (birch, rDer p2 or anti-IgE) resulted in 53.4% activation (30.8-66.8, P = 0.16 compared with grass). Desensitization reduced p38 MAPK phosphorylation from a median 48.1% (15.6-92.8) to 26.1% (7.4-71.2, P = 0.047) and correlated with decrease in CD63 upregulation (n = 7, r > 0.79, P < 0.05).

CONCLUSION

Desensitization attenuated basophil response rapidly and non-specifically at a stage before p38 MAPK phosphorylation.

In vitro diagnosis of Hymenoptera venom allergy and further development of component resolved diagnostics

For most people Hymenoptera stings result in transient and bothersome local inflammatory responses characterized by pain, itching, redness and swelling. In contrast, for those presenting an IgE-mediated allergic reaction, a re-sting may cause life-threatening reactions. In such patients, correct diagnosis is an absolute prerequisite for effective management, i.e. venom-specific immunotherapy. Generally, identification of the offending insect involves a detailed history along with quantification of venom-specific IgE antibodies and venom skin tests. Unfortunately, due to uncertainties associated with both tests, correct diagnosis is not always straightforward. This review summarizes the potentials and limitations of the various in vitro tests that are currently being used in the diagnosis of Hymenoptera venom allergy. Particular attention is paid to the potential of novel cellular tests such as basophil activation tests and component-resolved diagnosis with recombinant venom allergens in the diagnostic approach of patients with difficult diagnosis, i.e. cases in whom traditional venom specific IgE and skin tests yield equivocal or negative results. Finally, this review also covers the recent discoveries in the field of proteome research of Hymenoptera venoms and the selection of cell types for recombinant allergens production.

Basophil activation test in the diagnosis and monitoring of mastocytosis patients with wasp venom allergy on immunotherapy

BACKGROUND

There is need for an accurate diagnostic test in mastocytosis patients with wasp venom allergy (WVA) and monitoring of these patients during immunotherapy (IT). In this study, we aimed to evaluate sensitivity and specificity of the Basophil Activation Test (BAT) as a diagnostic and monitoring test in patients with mastocytosis and WVA.

METHODS

Seventeen patients with mastocytosis and WVA and six mastocytosis patients without WVA were included. BAT was performed before the start of IT (first visit) and at 6 weeks (second visit) and 1 year (third visit), after reaching the maintenance dose. Of 17 patients included, 11 completed the third visit. In mastocytosis patients with WVA, dose-dependent wasp-venom induced upregulation of CD63 and CD203c expression on basophils was observed compared with mastocytosis patients without WVA. Serum specific IgE, IgG4, and tryptase levels were measured in all patients.

RESULTS

BAT had a sensitivity of 87% and specificity of 100% in diagnosing WVA in mastocytosis patients. Basophil allergen threshold sensitivity with respect to CD63 and CD203c was significantly decreased in the second visit compared with the first visit and increased significantly in the third visit compared with the second visit. Specific IgE levels increased significantly in the second visit compared with first and decreased significantly in the third visit compared with the second. Specific IgG4 levels rose significantly in the second visit compared with the first and on the third visit compared with the second. Tryptase levels did not change significantly during the study.

CONCLUSIONS

BAT represents a diagnostic test with 100% specificity in allergic patients with mastocytosis and these patients are better to be monitored for a longer period during IT.

Flow cytometric allergy diagnosis: basophil activation techniques

The basis of flow cytometric allergy diagnosis is quantification of changes in expression of basophilic surface membrane markers (Ebo et al., Clin Exp Allergy 34: 332-339, 2004). Upon encountering specific allergens recognized by surface receptor FcεRI-bound IgE, basophils not only secrete and generate quantifiable bioactive mediators but also up-regulate the expression of different markers (e.g., CD63, CD203c) which can be detected by multicolor flow cytometry using specific monoclonal antibodies (Ebo et al., Cytometry B Clin Cytom 74: 201-210, 2008). Here, we describe two flow cytometry-based protocols which allow detection of surface marker activation (Method 1) and changes in intragranular histamine (Method 2), both reflecting different facets of basophil activation.

Basophil response and the induction of a tolerance in venom immunotherapy: a long-term sting challenge study

BACKGROUND

There is no in vitro test to predict the induction of long-term tolerance in patients treated with venom immunotherapy (VIT). The aim of this study was to investigate whether immunotherapy-induced changes in basophil responsiveness reflect a state of protection and the induction of a tolerance.

METHODS

Twenty-three patients with allergic reaction after Hymenoptera sting (11 wasp and 12 honeybee) were treated with VIT. In all patients, a CD63 basophil activation test was performed before the beginning of immunotherapy, after 1 year and after completing 4-6.5 years of immunotherapy (approximately 1 year after stopping). The tolerance was then evaluated by a sting challenge test. The basophil activation test was repeated 3-6 months after the challenge.

RESULTS

Twenty-two subjects showed a negative sting challenge, and one subject, a positive sting challenge. Allergen-specific basophil response remained unchanged after 1 year of immunotherapy. However, after immunotherapy, a significant and approximately fourfold decrease was demonstrated in all tolerant subjects mainly in response to submaximal 0.1 μg/ml allergen concentration. This depression was sustained and did not change with the sting challenge test. In a nontolerant patient with a positive sting challenge, basophil response did not change.

CONCLUSIONS

Our results suggest that the depression of allergen-specific basophil response seems to be associated with the induction of a tolerance after completing a course of VIT.

In vitro Biphasic Effect of Honey Bee Venom on Basophils from Screened Healthy Blood Donors

Apis mellifera L. bee venom is the most studied hymenoptera allergen, but many aspects of its action on human basophils remain unclear. Allergologists seek evidence of the effectiveness of bee venom immunotherapy as this approach is the chosen treatment for systemic allergic reactions. The effect of bee venom on human basophils in vitro has not been studied in detail for many reasons, including the paucity of basophils in peripheral blood, inter-individual basophil response variability, and the reliability and predictability of basophil activation tests. We conducted a brief preliminary survey of the effect of Apis bee venom on healthy asymptomatic (non-allergic) subjects. A dose of an aqueous commercial extract of Apis bee venom as high as 10 µg/mL activated resting basophils (CD63=+80-90%, CD203c=+30%), while it inhibited the expression of CD63 (-50%) following basophil stimulation by the soluble agonists formyl-Met-Leu-Phe or anti-IgE. The activation of resting basophils appeared to be dose-related. Only when basophils were activated with an IgE-mediated agonist, did bee venom extract exhibit a possible priming mechanism at the lowest doses used only via CD63, while it was ineffective via CD203c. Autocrine interleukin-3 may play a role in the observed biphasic behavior.