CIP2A Promotes T-Cell Activation and Immune Response to Listeria monocytogenes Infection.

The oncoprotein Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A) is overexpressed in most malignancies and is an obvious candidate target protein for future cancer therapies. However, the physiological importance of CIP2A-mediated PP2A inhibition is largely unknown. As PP2A regulates immune responses, we investigated the role of CIP2A in normal immune system development and during immune response in vivo. We show that CIP2A-deficient mice (CIP2AHOZ) present a normal immune system development and function in unchallenged conditions. However when challenged with Listeria monocytogenes, CIP2AHOZ mice display an impaired adaptive immune response that is combined with decreased frequency of both CD4+ T-cells and CD8+ effector T-cells. Importantly, the cell autonomous effect of CIP2A deficiency for T-cell activation was confirmed. Induction of CIP2A expression during T-cell activation was dependent on Zap70 activity. Thus, we reveal CIP2A as a hitherto unrecognized mediator of T-cell activation during adaptive immune response. These results also reveal CIP2AHOZ as a possible novel mouse model for studying the role of PP2A activity in immune regulation. On the other hand, the results also indicate that CIP2A targeting cancer therapies would not cause serious immunological side-effects.

Basophil activation test using recombinant allergens: highly specific diagnostic method complementing routine tests in wasp venom allergy.

BACKGROUND: Skin testing can expose allergic subjects to potential systemic reactions, sensitization against unrelated proteins, and increased risk of future sting reactions. Therefore the continuous improvement of in vitro diagnostic methods is desirable. Recombinant allergens have been shown to improve the sensitivity of specific IgE (sIgE) detection in vitro whilst no data is available regarding their application and reliability in basophil activation test (BAT). Here we aimed to compare the specificity and sensitivity of recombinant allergens Ves v 1, Ves v 2, Ves v 3 and Ves v 5 in both specific IgE (sIgE) detection in vitro and basophil activation test. METHODS: sIgE detection by ELISA or ImmunoCAP and BAT towards the panel of recombinant allergens Ves v 1, Ves v 2, Ves v 3 and Ves v 5 were performed in 43 wasp venom allergic patients with a history of anaphylactic reaction and sIgE seropositivity, as well as 17 controls defined as subjects with a history of repetitive wasp stings but absence of any allergic symptom. RESULTS: The BAT performed with the recombinant allergens Ves v 1, Ves v 2, Ves v 3 and Ves v 5 markedly improved the specificity of diagnosis in wasp venom allergic subjects when compared to the respective sIgE detection in serum. CONCLUSIONS: BAT performed with the recombinant allergens Ves v 5, Ves v 3 and Ves v 1 provides an emerging highly specific in vitro method for the detection of wasp venom allergy, compared to the sIgE detection. Recombinant allergens applied to BAT represent a step forward in developing reliable in vitro tests for specific diagnosis of allergy.

Identification, recombinant expression, and characterization of the 100 kDa high molecular weight Hymenoptera venom allergens Api m 5 and Ves v 3.

Insect stings can cause life-threatening IgE-mediated anaphylactic reactions in venom-allergic patients. Although several compounds have already been described as venom allergens, prominent allergen candidates especially in the higher m.w. range have still remained elusive. Tandem mass spectrometry-based sequencing assigned a candidate gene to the most prominent putative high m.w. allergen Api m 5 (allergen C) in honeybee (Apis mellifera) venom and also allowed identification of its homologue Ves v 3 in yellow jacket (Vespula vulgaris) venom. Both proteins exhibit a pronounced sequence identity to human dipeptidyl peptidase IV or CD26. Reactivity of a human IgE mAb verified the presence of these proteins in the venoms. Both proteins were produced in insect cells and characterized for their enzymatic activity as well as their allergenic potential using sera and basophils from insect venom-allergic patients. Both Api m 5 and Ves v 3 were recognized by specific IgE of the majority of patients even in the absence of cross-reactive carbohydrate determinants. Serologic IgE reactivity closely matched activation of human basophils by Api m 5 or Ves v 3, thus underlining their relevance in functional assays. With Api m 5 and Ves v 3, a new pair of homologous allergens becomes available for future clinical applications in diagnosis and therapy that may also contribute to the understanding of molecular mechanisms of insect venoms. Moreover, the patient IgE reactivity together with the cellular activation demonstrates for the first time the relevance of high m.w. allergens in the context of hymenoptera venom allergy.

Molecular cloning and expression in insect cells of honeybee venom allergen acid phosphatase (Api m 3).

BACKGROUND: Acid phosphatase (Api m 3) is a major allergen in honeybee (Apis mellifera) venom, and its availability as a recombinant protein may facilitate the development of improved diagnostic tests and immunotherapies. OBJECTIVE: One objective is the determination of the complete primary structure of Api m 3 and to obtain recombinant Api m 3 on the basis of expression in insect cells. Another objective is the quantitative analysis of patient serum IgE antibody reactive to recombinant Api m 3. METHODS: The cloning of Api m 3 from venom gland cDNA and its expression as a full-length protein in eukaryotic insect cells is described. The immunoreactivity of serum IgE antibodies of honeybee venom-sensitized patients to recombinant Api m 3 was determined in an enzyme immunoassay. RESULTS: PCR amplification generated a 1122-bp DNA fragment whose identity as the coding sequence of Api m 3 was verified by several means. Recombinant Api m 3, expressed in Trichoplusia ni cells, showed an expected molecular weight and enzymatic activity at pH 4.5. Analysis of tryptic fragments of purified recombinant Api m 3 by mass spectrometry confirmed its identity. In immunoassays, recombinant Api m 3 is specifically recognized by IgE antibodies of pooled serum in Western blots and by 37% of the individual sera of honeybee venom-sensitized patients in ELISA analysis. CONCLUSION: The availability of recombinant Api m 3 provides a tool for both the development of improved diagnostic tests and the design of safer and more effective immunotherapeutic approaches for honeybee venom allergy. CLINICAL IMPLICATIONS: The recombinant venom allergen Api m 3 is a key element in the search for an optimized component-resolved approach to honeybee venom allergy with regard to both the development of superior diagnostic tests and the improvement of allergen immunotherapy.