Control of IgE synthesis in man

The relationship between IgE-mediated and cell-mediated hypersensitivities in an unselected Danish population: the Glostrup Allergy Study, Denmark

In this study, we have assessed the relationship between IgE-mediated and cell-mediated hypersensitivities in an unselected population living in western Copenhagen, Denmark. A total of 793 subjects, aged 15-69 years, were studied. Measurements of total serum IgE, prick tests with aero-allergens and patch tests with environmental haptens were performed in 561 (70.7% of 793) subjects. One or more positive prick tests were present in 28.4%, and contact sensitization occurred in 15.2%. When adjusted for the effects of sex and age, the probability of contact sensitization to one or more hapten was independent of serum IgE level (the odds ratio value (OR) = 1.0; 95% confidence interval (CI) = 0.7-1.4), and the probability of contact sensitization was independent of the number of positive prick tests (OR = 1.0; CI = 0.8-1.2). Contact sensitization appeared to be independent of enhanced IgE responsiveness in an unselected adult population.

Relative risks of bronchial hyper-responsiveness associated with skin-prick test responses to common antigens in young adults

We studied 143 young subjects by skin-prick testing to common allergens and by the measurement of non-specific bronchial responsiveness (NSBR). A logistic regression model showed a prevalence odds ratio (POR) for bronchial hyper-responsiveness (PD20 less than 10 mumol methacholine) in house dust positive subjects of 4.10 (95% CI 1.77-9.51, P less than 0.001), and in mould positive subjects 5.72 (95% CI 2.06-15.9, P less than 0.001): the PORs for epithelia (2.05, P = 0.12) and grasses (1.78, P = 0.19) were not significant. If bronchial reactivity was assessed as measurable (PD20 less than 102 mumol methacholine) or not, the POR for house-dust-positive subjects was 4.83 (95% CI 2.23-10.5, P less than 0.001), for moulds was 10.5 (95% CI 2.33-47.5, P less than 0.001), for epithelia was 4.79 (95% CI 1.91-12.0, P less than 0.001), and for grasses was 2.21 (95% CI 1.11-4.4, P = 0.022). The results show the risk of bronchial hyper-responsiveness is greater in subjects sensitive to house dust and mould than in those reactive to grasses, and suggests that the presence or absence of increased NSBR in atopic individuals may depend on the antigens to which they become sensitized.

Evidence suggesting involvement of interleukin-4 (IL-4) production in spontaneous in vitro IgE synthesis in patients with atopic dermatitis

To investigate the regulatory role of interleukin-4 (IL-4) and interferon-gamma (INF-gamma) and their involvement in the abnormality of IgE synthesis in patients with atopic dermatitis (AD), we studied the effect of recombinant human IL-4 and INF-gamma, as well as blocking antibodies (Abs) to these lymphokines on spontaneous IgE synthesis by peripheral blood lymphocytes (PBLs) from patients with AD and from healthy control subjects. PBLs from patients with AD demonstrated elevated spontaneous IgE production that was not stimulated further by the addition of recombinant IL-4, whereas for the healthy control subjects, recombinant IL-4 increased spontaneous IgE production by PBLs. INF-gamma that has been previously demonstrated to antagonize the effect of IL-4 on IgE synthesis, decreased IgE production of patients with AD. Addition of Abs to INF-gamma did not change spontaneous IgE production for patients with AD or for healthy control subjects. Together with our observation that IL-4 Abs lowered the high spontaneous IgE production by PBLs from patients with AD, these results suggest that in AD, IL-4 production by lymphocytes, together with a lack of INF-gamma production, is at least partially responsible for the increased spontaneous IgE production.

Human IgE mRNA expression by peripheral blood lymphocytes stimulated with interleukin 4 and pokeweed mitogen

Expression of human IgE mRNA by peripheral blood lymphocytes (PBL) and an IgE-producing myeloma cell line, U-266, was examined by Northern blot hybridization and compared with IgE levels in culture supernatants. A 2.35-kb IgE mRNA was detected in unstimulated atopic PBL and U-266 cells but not in normal PBL, and its levels correlated with IgE protein levels in the supernatant. Upon stimulation with interleukin 4, a new 1.75-kb transcript was revealed in both atopic and normal PBL but not in U-266 cells. Its expression did not correlate with IgE levels in the supernatant. Pokeweed mitogen also induced the expression of the 1.75-kb transcript without concomitant induction of IgE synthesis by normal PBL and even suppressed the spontaneous expression of the 2.35-kb transcript and IgE protein synthesis by atopic PBL. Interferon-gamma, which suppressed both the 2.35-kb transcript and IgE protein production, had no inhibitory effect on the 1.75-kb transcript. Expression of the 1.75-kb transcript was already high after 2 days of stimulation and peaked around day 4. The length of the transcript is smaller than that of mRNA coding for secreted human IgG and IgA and contains all four C epsilon exon sequences, suggesting it might be a truncated transcript without v region and might be a human counterpart of the murine germ-line C epsilon transcript.

IgE, IgA and IgG antibodies and delayed skin response towards Candida albicans antigens in atopics with and without saprophytic growth

Immunoblotting and RAST were used to analyse IgE, IgA and IgG responses to antigens of Candida albicans. These were compared with the delayed skin response and C. albicans carriage in 40 atopic subjects. The majority of the atopic patients showed a strong IgG and IgA antibody response towards mannan, a carbohydrate, but only occasionally to proteins. Altogether 22 of the 40 patients showed specific IgE towards C. albicans by immunoblotting. The IgE response was mainly towards proteins, particularly to ones with molecular weights of 29 kD and 46 kD, and only in eight out of 22 IgE-positive subjects towards mannan. The IgG and IgA responses to mannan and the total IgE response towards C. albicans assessed by RAST showed an association with C. albicans carriage, whereas the delayed skin response showed an inverse relationship. The immunological parameters characteristic of C. albicans carriage were found to be C. albicans-specific depressed delayed skin response and elevated IgE, IgA and IgG responses. This situation in the atopics presenting such parameters may favour simultaneous sensitization and exposure by colonization. The degree of sensitization may be sufficiently high to produce symptomatic allergy, such as asthma, in some individuals during occasional overgrowth of C. albicans, e.g. due to antibiotic therapy.

Enumeration of IgE secreting B cells. A filter spot-ELISA

To assess the frequency of IgE producing cells in humans a filter immunoplaque assay has been developed to detect IgE secretion from individual B lymphocytes in unfractionated peripheral blood mononuclear cells (PBMC). PBMC were incubated in microfilter plates containing nitrocellulose membranes coated with polyclonal anti-human IgE antibody, and the IgE production by a single cell was detected using a specific anti-human IgE monoclonal antibody followed by enzymatic development. The products of the enzymatic reaction were visualized as blue plaques on the membranes. The assay was both sensitive and specific as determined by: (1) a near 1:1 correlation between direct cell counts of an IgE producing myeloma cell line (U266) and the number of plaques in the filter immunoassay; and (2) the absence of detectable plaques generated by human B cells transformed by Epstein-Barr Virus (EBV) and producing only IgG or IgM. The presence of other cell types in PBMC did not affect the ability to detect IgE secreting cells. Replicate cultures of highly purified B lymphocytes, first transformed with EBV and then stimulated with recombinant human interleukin-4, produced IgE levels in culture supernatants that correlated closely with the number of IgE producing cells (r = 0.93; P less than 0.001). Furthermore, using the same transformed cells, the number of IgE secreting cells assessed by the immunoplaque assay was significantly correlated (r = 0.94; P = 0.002) with the number of IgE producing cells assessed by immunofluorescence staining of intracytoplasmic IgE. This assay provides a simple and direct method to assess the frequency of IgE producing lymphocytes in humans.

Regulation of immunoglobulin (Ig)E synthesis in the hyper-IgE syndrome

The hyper-IgE (HIE) syndrome is characterized by high IgE serum levels, chronic dermatitis, and recurrent infections. The mechanisms responsible for hyperproduction of IgE in HIE patients are presently unknown. We investigated whether spontaneous in vitro IgE synthesis by PBMC from seven HIE patients was sensitive to signals (cell adhesion, T/B cell cognate interaction and lymphokines: IL-4, IL-6, and IFN-gamma) known to regulate IgE induction in normals. Our results show that, unlike IL-4 dependent IgE synthesis induced in normals, spontaneous IgE production by PBMC from HIE patients was not blocked by monoclonal antibodies to CD2, CD4, CD3, and MHC class II antigens. Furthermore, antibodies to IL-4 and IL-6 did not significantly suppress IgE production. IFN-gamma had no significant effects on spontaneous in vitro IgE synthesis. To test whether an imbalance in lymphokine production might underlie hyperproduction of IgE in HIE patients, mitogen-induced secretion of IL-4 and IFN-gamma by PBMC was assessed. No significant difference was detected between HIE patients and normal controls. Thus, ongoing IgE synthesis in the HIE syndrome is largely independent of cell-cell interactions and endogenous lymphokines, and is due to a terminally differentiated B cell population, no longer sensitive to regulatory signals.

Linkage between immunoglobulin E responses underlying asthma and rhinitis and chromosome 11q

Family studies of IgE responses to common inhaled antigens have suggested dominant inheritance of atopy. Molecular genetic linkage analysis was used to confirm this proposal. In seven families the transmission of atopy was linked, with a maximum lod score of 5.58, to a DNA polymorphism defined by p lambda MS.51, which confirms dominant inheritance and assigns the gene locus to chromosome 11.

Basophil histamine release and lymphocyte proliferation tests in latex contact urticaria. In vitro tests in latex contact urticaria

Basophil histamine release and lymphocyte proliferation tests were examined with latex allergen prepared from surgical gloves in 15 patients with latex contact urticaria. The basophil histamine release test (BHRT) yielded positive results in 13/14 (93%) patients, whereas commercial latex RAST was positive in only 9/15 (60%) patients. Lymphocyte proliferation test (LPT) was positive in 3/15 (20%) patients, suggesting that cell-mediated immune reactions may also occur in latex allergy. However, patch tests to latex were negative and neither were epidermal Langerhans cells able to present latex antigen to T lymphocytes in vitro.

Transfer of allergen-specific IgE-mediated hypersensitivity with allogeneic bone marrow transplantation

We investigated whether allergen-specific IgE-mediated hypersensitivity is transferred by bone marrow transplantation. Twelve patients, 14 to 47 years of age, undergoing allogeneic bone marrow transplantation for the treatment of hematologic cancer were selected, along with their donors, by a screening questionnaire for a history of atopy in the donor. We evaluated these donor-recipient pairs before transplantation and at several points afterward for immediate skin-test reactivity to 17 allergens. For allergens for which pretransplantation skin tests had been positive in the donors and negative in the recipients, 20 of 46 post-transplantation skin tests were positive in 8 of the 11 recipients who survived for more than one year after transplantation. For allergens for which both donors and recipients had had negative skin tests before transplantation, only 6 of 256 tests (2.3 percent) were positive in the recipients after transplantation. Long-term transfer of donor-derived mite-specific IgE was demonstrated by radioallergosorbent testing in two recipients. Seven recipients either acquired or had an exacerbation of allergic rhinitis, and two recipients without a history of asthma had asthma one year after transplantation. We conclude that allergen-specific IgE-mediated hypersensitivity is adoptively transferred by bone marrow transplantation from donor to recipient by B cells with allergen-specific memory.

Allergy in asthma. II. The highly atopic infant and chronic asthma

The relationship between allergy and asthma in infants and preschool children was investigated. One hundred nine children, median age 2 1/2 years, were examined immunologically by quantitation of serum IgE, RAST testing to 13 allergens, and culture of peripheral blood lymphocytes for spontaneous IgE formation. We examined a cross-section of infants and toddlers to determine whether the severity of asthma is associated with allergy as has been reported in older children with asthma. We identified a group of highly atopic infants and preschool children who have serum IgE at least 10 times the mean + 1 SE for age, multiple positive RASTs with early formation of IgE to inhalant antigens, and circulating B cells that spontaneously form IgE when these are cultured in vitro. Such highly atopic infants and preschool children were statistically more likely to have chronic asthma requiring multiple continuous medication compared to the rest of the population (p less than 0.01).