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Local respiratory allergy (LRA) is defined by the negativity of atopy tests, a clinical history suggestive of airway allergy and a positive response to the nasal and/or bronchial allergen challenge. The clinical spectrum of LRA is comprised of three conditions: local allergic rhinitis (LAR) and local allergic asthma in non-atopic patients, and dual allergic rhinitis (coexistence of allergic rhinitis and LAR) in atopic individuals. LRA is an independent disease phenotype not progressing to atopy over time, but naturally evolving to the clinical worsening and the onset of comorbidities. Published data suggests that LRA is mediated through the mucosal synthesis of allergen-specific (s)IgE, which binds to FcϵRI on resident mast cells, and in >50% of cases traffics to the blood stream to sensitize circulating basophils. To date, 4 clinical trials have demonstrated the capacity of allergen immunotherapy (AIT) to decrease nasal, conjunctival and bronchial symptoms, to improve quality of life, to increase the threshold dose of allergen eliciting respiratory symptoms, and to induce serum sIgG4 in LRA individuals. Collectively, these data indicate that local allergy is a relevant disease mechanisms in both atopic and non-atopic patients with airway diseases.

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SUMMARY Neonatal B cells have been considered immature because of their impaired capacity to produce immunoglobulins in response to polyclonal activators in vitro. Here we demonstrate that cord blood mononuclear cells (MNC) produce normal levels of IgE in vitro when cultured in the presence of interleukin-4 (IL-4), indicating that the B cells are mature in their capacity to switch to IgE-producing cells. However, in contrast to adult peripheral blood T cells, cord blood T cells failed to produce detectable levels of IL-4 upon activation by phytohaemagglutinin (PHA) concanavalin A (Con A) or combinations of PHA and the phorbol ester TPA. Interferon-gamma (IFN-γ) production by cord blood T cells following activation by Con A or PHA was also strongly reduced. However, high levels of IFN-γ, significantly higher than those produced by adult T cells, were synthesized in response to combinations of PHA and TPA, indicating that IFN-γ production by cord blood T cells is not intrinsically defective. In contrast, cord blood T cells produced levels of IL-2 that were significantly higher than those obtained by adult T cells tested in parallel. Collectively, our data indicate that the minimal levels of IgE production measured in cord blood (< 1 U/ml) are not due to immaturity of the cord blood B cells, but may be associated with the failure of cord blood T cells to produce detectable levels of IL-4, which has been shown to be responsible for induction of IgE synthesis both in vitro and in vivo.

SUMMARYInterleukin-4 (IL-4) has been shown to induce IgE synthesis by peripheral blood mononuclear cells (PBMC) of normal donors in vitro. However, induction of PBMC of patients with common variable immunodeficiency (CVI) with IL-4 resulted in IgE production in only two out of eight cases tested. PBMC of the first patient that produced IgE in response to IL-4 also secreted normal levels of IL-4 upon activation. PBMC of the second patient secreted very low levels of IL-4 in vitro which may account for the very low serum IgE levels in this patient. Of the other six patients who had very low serum IgE levels and whose PBMC failed to produce IgE in response to IL-4 in vitro, five did not secrete IL-4 upon in vitro activation. The capacity of the T cells to produce IL-4 was intact in the sixth patient. Collectively our data indicate the PBMC of the majority of patients with CVI are defective since they failed to respond appropriately to IL-4 and they failed to produce IL-4, contributing to the view that CVI is a heterogeneous disorder in which a variety of T and B cell defects occur.