Affinity-purified soluble Fc epsilon RII/CD23 derived from RPMI-8866 cells induces histamine release from human nasal polyp mast cells through a non-IgE-mediated mechanism

Critical role of CD23 in allergen-induced bronchoconstriction in a murine model of allergic asthma

CD23-deficient and anti-CD23 monoclonal antibody-treated mice were used to investigate the role of the low-affinity receptor for IgE (CD23) in allergic airway inflammation and airway hyperresponsiveness (AHR). While there were no significant differences in ovalbumin (OVA)-specific IgE titers and tissue eosinophilia, evaluation of lung function demonstrated that CD23-/- mice showed an increased AHR to methacholine (MCh) when compared to wild-type mice but were completely resistant to the OVA challenge. Anti-CD23 Fab fragment treatment of wild-type mice did not affect the MCh-induced AHR but significantly reduced the OVA-induced airway constriction. These results imply a novel role for CD23 in lung inflammation and suggest that anti-CD23 Fab fragment treatment may be of therapeutic use in allergic asthma.

Inhibition of sCD23 and immunoglobulin E release from human B cells by a metalloproteinase inhibitor, GI 129471

Soluble CD23 (sCD23) has been proposed to play an important role in the up-regulation of immunoglobulin E (IgE) synthesis. Production of sCD23 is dependent on the proteolytic cleavage of membrane CD23, but the protease(s) involved in this process remain unknown. Preliminary data, obtained by testing a panel of protease inhibitors, suggested that this enzyme may be a zinc-dependent metalloproteinase. Therefore, we investigated the effect of a standard hydroxamate-type Zn2+ metalloproteinase inhibitor (GI 129471) on both sCD23 and IgE release from human tonsillar B cells, stimulated with interleukin-4 (IL-4) and anti-CD40. Incubation of cells for 3 days with GI 129471 inhibited the production of sCD23 with an IC50 of 602 nm+/-3 nm (n=3), but by 14 days the activity of the compound against sCD23 had decreased by greater than threefold (IC50 2+/-0.26 microM; n=3). On the other hand, GI 129471 caused a potent inhibition of IgE production, with no apparent loss of activity over the culture period (14 days: IC50 250 nm+/-72 nm; n=3). Time-course studies showed that, despite loss of activity against sCD23, inhibition of sCD23 production early in the culture was able to cause a potent and long-lasting inhibitory effect on IgE. Furthermore, we also showed that the activity of GI 129471 is selective for IgE, as no effect was seen on immunoglobulin G1 (IgG1) or IgG4 production at test concentrations as high as 10 microM. These results support the hypothesis that metalloproteinases may be involved in the proteolytic cleavage of CD23 and subsequent regulation of IgE synthesis. Inhibition of the protease(s) responsible for such cleavage may be of value in the treatment of allergic disease.

Triggering through CD40 promotes interleukin-4-induced CD23 production and enhanced soluble CD23 release in atopic disease

The pathogenesis of atopic disease is closely linked to the overproduction of IgE. CD23 and CD40 are two cellular receptors involved in the regulation of IgE production and both receptors are elevated in atopic disease. We have examined the role of CD40 in the regulation of CD23 and soluble CD23 production in healthy and atopic donors. Triggering of the B cell CD40 receptor directly enhances interleukin (IL)-4-mediated up-regulation of CD23 at both the protein and the mRNA level. When atopic donors were studied, the synergistic effect of CD40 triggering on the IL-4-induced up-regulation of CD23 and soluble CD23 (sCD23) was enhanced and there was a relative skewing toward production of sCD23. These studies implicate the CD40 receptor in the hyperproduction of CD23 and sCD23 in atopic disease and suggest that abnormalities may exist in the cellular pathways leading to sCD23 production.

Arachidonic acid metabolites and sinonasal polyposis. I. Possible prognostic value

PURPOSE

The etiology of sinonasal polyps is sometimes obscure. This study was undertaken to evaluate the potential role of arachidonic acid metabolites (AAm) on recurrent polyposis.

MATERIALS AND METHODS

Tissue production of prostaglandin E2 (PGE2), 6-keto-prostaglandin F1-alpha (PGI2), thromboxane A2 (TxA2), and leukotriene C4 (LTC4) by nasal mucosa was determined by radioimmunoassay in 27 patients with sinonasal polyposis (SNp) and in 10 volunteers.

RESULTS

The group of patients with SNp with the evidence of recurrences in postoperative period (Group 1) showed significantly lower PGE2 concentrations than group of patients with SNp recurrences (Group 2). The differences in concentrations of PGI2 in mentioned groups were insignificant. In comparison with other groups, a group of patients who underwent surgery several times for SNp (Group 4) had a higher mean TxA2 concentration. The LTC4 concentrations were the highest in groups of patients where SNp recurrences were observed. When the incidence of polyposis recurrences (within 18 months after surgery) was correlated with the level of LTC4 production at the time of surgery, the rate of recurrence was significantly higher in patients with increased LTC4 level than in those with normal LTC4 levels.

CONCLUSIONS

LTC4 might have a prognostic value. The possible role of AAm in occurrence of SNp is apparent and suggests possible role for medical intervention.

Soluble CD23 in human immunodeficiency virus type 1 infected patients

The level of sCD23 produced in the course of human immunodeficiency virus (HIV) infection was measured in patients grouped according to the Centers for Disease Control by using an immunoradiometric assay. Soluble CD23 was evaluated in supernatants of peripheral blood mononuclear cell (PBMC) (10(6) cells/ml) stimulated by phytohemagglutinin (PHA). Compared with healthy controls (m +/- S.D. = 1.0 +/- 0.34 U/ml, n = 7), higher values were observed in some of the patients of group II (asymptomatic) (m +/- S.D. = 2 +/- 1.33, n = 9) and some of the patients of group IV (AIDS) (m +/- S.D. = 1.3 +/- 1.40, n = 8). Those results prompted us to compare the plasma levels of sCD23 in group II and group IV HIV-infected patients and in healthy individuals. Soluble CD23 plasma levels in healthy patients (n = 42) ranged from 0 to 1.5 U/ml (m +/- S.D. = 0.9 +/- 0.33), in group II patients (n = 17) from 0 to 3 U/ml (m +/- S.D. = 0.92 +/- 0.83) and in group IV patients (n = 73) from 0 to 2.9 U/ml (m +/- S.D. = 1.15 +/- 0.71). The differences between the patients and the healthy individuals were not statistically significant but individual sCD23 values higher than 2 U/ml were obtained in 6% of the group II patients and 16.7% of the group IV patients. Increased values of sCD23 were obtained in plasma from patients with secondary infectious diseases (groups IV-Cl and IV-C2) and from patients without secondary infectious diseases (group II, group IV-A and group IV-B).(ABSTRACT TRUNCATED AT 250 WORDS)

Levels of serum IgE, serum soluble-Fc epsilon RII, and Fc epsilon RII(+) peripheral blood lymphocytes in atopic dermatitis

Levels of serum IgE, serum soluble-Fc epsilon RII (S-Fc epsilon RII), and Fc epsilon RII(+) peripheral blood lymphocytes (PBL) were examined in 73 patients with atopic dermatitis (AD) and 17 control subjects with no atopic disease, in order to investigate the correlation of these parameters with AD. AD patients showed increases in IgE, S-Fc epsilon RII and Fc epsilon RII(+)PBL as compared with control subjects. In AD patients, levels of serum IgE and Fc epsilon RII(+)PBL increased as the extent of dermatitis became more severe, while levels of serum S-Fc epsilon RII showed no correlation with the extent of dermatitis. In 8 of the 73 AD patients who showed an improvement in their symptoms with treatment with topical corticosteroids or antihistamine, IgE, Fc epsilon RII(+)PBL, and S-Fc epsilon RII were measured before and after treatment. Fc epsilon RII(+)PBL correlated with disease activity; IgE and S-Fc epsilon RII did not show any such correlation. Patients with elevated IgE levels (IgE greater than 5,000 U/ml) showed low levels of S-Fc epsilon RII. Severely affected cases with a history of respiratory atopy also showed decreased S-Fc epsilon RII levels. It is believed that S-Fc epsilon RII binds to IgE in serum and may neutralize or down-regulate IgE mediated allergic reactions. A low level of S-Fc epsilon RII may cause an elevation of IgE and an exacerbation of the disease.