The IgE receptor of eosinophils

Moniezia benedeni infection increases IgE+ cells in sheep (Ovis aries) small intestine

The concentration of immunoglobulin (Ig) E is the lowest among serum Igs, but it can induces type I hypersensitivity and plays an important role in anti-parasitic infection. The present study aimed to explore the residence characteristics of IgE+ cells in the sheep small intestine and the impact of Moniezia benedeni infection on them. The recombinant plasmids pET-28a-IgE were constructed and induced and expressed in Escherichia coli. BL21 (DE3). The rabbit anti-sheep IgE polyclonal antibody was prepared using the obtained recombinant protein as antigen. Finally, the levels of IgE+ cells in the small intestine of healthy (Control group) and naturally M. benedeni-infected (Infected group) sheep were detected analyzed. The results showed that the rabbit anti-sheep IgE polyclonal antibody with good immunogenicity (titer = 1: 128000) could specifically bind to the heavy chain of natural sheep IgE. In the Control group, the IgE+ cells were mainly distributed in lamina propria of the small intestine, and the densities were significantly decreased from duodenum to ileum (P<0.05), with respective values of (4.28 cells / 104 μm2, 1.80 cells / 104 μm2, and 1.44 cells / 104 μm2 in duodenum, jejunum, and ileum. In the Infected group, IgE+ cells density were 6.26 cells / 104 μm2, 3.01 cells / 104 μm2, and 2.09 cells / 104 μm2 in duodenum, jejunum and ileum respectively, which were significantly higher in all segments compared to the Control group (P<0.05), increasing by 46.26%, 67.22% and 45.14%, respectively. In addition, compared with the Control group, the IgE protein levels were significantly increased in all intestinal segments of the Infected group (P<0.01), however, there was no significant differences among the different intestinal segments within the same group (P>0.05). The results demonstrated that M. benedeni infection could significantly increase the content of IgE and the distribution density of its secreting cells in sheep small intestine. The intestinal mucosal immune system of sheep presented obvious specificity against M. benedeni infection. This lays a good foundation for further exploring molecular mechanisms of the intestinal mucosal immune system monitoring and responding to M. benedeni infection.

Allergic airway sensitization induces T cell activation but not airway hyperresponsiveness in B cell-deficient mice

B cells play an important role in the allergic response by producing allergen-specific Igs as well as by serving as antigen-presenting cells. We studied the involvement of B cells in the development of responses in a murine model of allergic airway sensitization. Normal and B cell-deficient (muMt-/-) B10.BR mice were sensitized via the airways to ovalbumin; Ig production, cytokine elaboration from local lymph node cells, development of airway hyperresponsiveness, and histological changes in the airways were evaluated. Both strains of mice had increased production of T helper 2-like cytokines and developed an accumulation of eosinophils in the bronchial tissue after airway sensitization. However, only wild-type mice produced allergen-specific antibodies and exhibited altered airway function. B cell-deficient mice reconstituted with anti-ovalbumin IgE during the course of sensitization developed increases in airway responsiveness. These results indicated that neither B cells nor IgE were necessary for the induction of a T helper 2-type cytokine response or eosinophil infiltration of the airways after allergic sensitization but that IgE was required as a second signal for the development of airway hyperresponsiveness in this model of airway sensitization.

Allergen-induced CD23 on CD4+ T lymphocytes and CD21 on B lymphocytes in patients with allergic asthma: evidence and regulation

Interaction of CD4+ T cells and B cells is necessary for IgE production. It has been recently demonstrated that cell surface antigen CD21 is a ligand for CD23 (Fc epsilon RII) and that the pairing of these molecules may participate in the control of IgE production. In this study we investigated the effect of the Dermatophagoides pteronyssinus (Dpt) allergen and recombinant interleukin(rIL)-4 on the expression of CD21 and CD23 on T and B cells of asthmatic patients allergic to Dpt and of healthy controls. Peripheral blood mononuclear cells (PBMC) were incubated alone or with Dpt allergen (100 biological units/ml) and/or rIL-4 (100 U/ml) for up to 7 days. The flow-cytometric analysis of double-fluorescence staining revealed that Dpt allergen and/or rIL-4 induced CD23 on CD4+ T lymphocytes only in allergic patients. The allergen-induced CD23 on T cells is de novo synthesized antigen since no induction of CD23 on T cells was observed in cultures with 0.4 microgram/ml actinomycin D. Moreover, 100 U/ml of interferon-gamma inhibited the induction of CD23 on CD4+ T cells. T cells obtained from healthy donors did not express CD23 or CD21 antigen upon incubation with allergen and/or rIL-4. Although rIL-4 also induced CD23 in controls, the expression was only observed on CD20+ cells. The allergen alone induced a significant elevation of the mean fluorescence intensity of both CD21 and CD23 only in allergic individuals. When the cell proliferation was analyzed, a slightly increased stimulation index upon cultivation of PBMC was obtained from non-allergic donors as well, but less than in allergic patients. The co-expression of major histocompatibility complex class II molecules and CD23 on CD4+ T lymphocytes in allergic patients, as assessed by the three-color immunofluorescence analysis, indicates that these cells were activated. We conclude that CD4+ T lymphocytes possess a unique capability to express CD23 upon exposure to allergen. Moreover, the allergen-mediated induction of CD23 on T cells observed only in allergic patients may be the reason for the increase of IgE production. This would not occur in non-allergic individuals as there is no CD23 expression on T cells.

IgE, Reed-Sternberg cells, and eosinophilia in Hodgkin's disease

Tissues containing Hodgkin's disease tumors of the nodular sclerosis and mixed cellularity subtypes are frequently infiltrated by numerous degranulating eosinophils that release granule proteins such as eosinophil peroxidase and major basic protein. Until recently, the causes of the eosinophil infiltration and degranulation in Hodgkin's disease tumors were unknown. Analysis of Hodgkin's disease tissues by a sensitive and specific immunoperoxidase technique has now demonstrated the extensive presence of IgE in the Reed-Sternberg cells and adjacent cells of Hodgkin's disease tumors. Because eosinophils express a cell-surface receptor (CD23) for IgE and degranulate in the presence of IgE deposits, the extensive eosinophilia that is frequently present in Hodgkin's disease tumors is, at least in part, attributable to the IgE deposits within the tumor. In this review, we discuss the possible mechanisms and biological significance of IgE-related eosinophilia in Hodgkin's disease.