Ragweed IgE and IgG4 antibody in nasal secretions during immunotherapy

Immunotherapy in food allergy

Food allergies are caused by immune responses to food proteins and represent a breakdown of oral tolerance. They can range from mild pruritus to life-threatening anaphylaxis. The only current consensus for treatment is food avoidance, which is fraught with compliance issues. For this reason, there has been recent interest in immunotherapy, which may induce desensitization and possibly even tolerance. Through these effects, immunotherapy may decrease the potential for adverse serious reactions with accidental ingestions while potentially leading to an overall health benefit. In this review, we discuss the mechanisms of food allergy and give an overview of the various immunotherapeutic options and current supporting evidence, as well as look towards the future of potential novel therapeutic modalities.

Undetectable IgE responses after respiratory syncytial virus infection

Sequential nasopharyngeal secretions were collected from 81 infants from one day to three months after admission to hospital with respiratory syncytial virus (RSV) infection. Samples from 21 infants were assayed for anti-RSV IgE in an antigen capture ELISA assay. No IgE antibodies were detected although an assay of IgA antibodies carried out in parallel by a similar technique detected IgA antibodies in the secretions of all patients tested. Neither prior absorption of IgA or IgG, concentration of the secretions by freeze drying, nor enzyme amplification of the assay revealed any virus specific IgE. Using an antibody capture ELISA with a sensitivity of 0.85 IU/ml, IgE could be detected in sequential secretions of only one of the 81 RSV infected infants studied. Further testing of the secretions from 12 of these patients and those of a further 15 using an enzyme amplified assay with a sensitivity of 0.1 IU/ml revealed no further positives. Low concentrations of IgE were found in the sera of the majority of infants with RSV infection but they did not differ from those of virus negative children of a similar age collected between RSV epidemics. No rise in mean serum IgE concentrations between acute and convalescent samples was observed. No virus specific IgE was detected in the sera of any infant using the enzyme amplified antigen capture ELISA.

Tryptase and histamine release due to a sting challenge in bee venom allergic patients treated successfully or unsuccessfully with hyposensitization

BACKGROUND

Hyposensitization with been venom leads to full protection in most, but not all patients with IgE-mediated systemic reactions to bee stings.

OBJECTIVE

To determine the relationship of clinical reactivity to the release of mediators and to changes of antibody concentrations in the peripheral circulation at a bee sting challenge test.

METHODS

Blood was sampled before (1 min) and at 15, 60 and 180 min after a sting challenge from 19 patients on hyposensitization. Of these six still reacted and 13 were protected. Histamine, mast cell tryptase, bee venom-specific IgE and IgG in the serum, and histamine release from peripheral blood leucocytes (PBL) upon exposure to bee venom were determined.

RESULTS

Tryptase above the detection level was found only at 15 (60) min in 4/6 (1/6) patients who reacted. After the sting challenge there was a significant increase of the histamine levels in patients who reacted at 15 min (P < 0.05) and in patients who did react at 60 and 180 min (P < 0.01). The total histamine content of PBL was significantly decreased after 15 and 60 min in patients who reacted (P < 0.01) and in those that did not (P < 0.05). Bee venom-induced histamine release was significantly reduced in patients reacting and those that did not at 15 min (P < 0.05), and was significantly decreased in reactors also at 60 and 180 min (P < 0.05/0.01). Specific IgG antibodies showed a minor decrease (P < 0.05) after the sting challenge in both groups, whereas specific IgE did not change significantly.

CONCLUSION

These results indicate that bee venom anaphylaxis is associated with the release of mediators from both mast cells as well as basophils. Successful hyposensitization does not induce a state of immunological non-reactivity, but rather alters the magnitude and the pattern of mediator release.

Changes in nasal specific IgE to mites after periods of allergen exposure-avoidance: a comparison with serum levels

Variations of serum and nasal specific IgE to Dermatophagoides pteronyssinus (Der p) during alternate periods of antigen avoidance-exposure have been evaluated with an open design in a group of allergic children with asthma and rhinitis at the residential house Istituto Pio XII (Misurina, BL, Italy), at 1756 m, in the Italian Dolomites. A method based on direct incubation of allergen coupled substrate on the nasal mucosa has been employed to evaluate the levels of nasal IgE. Serum specific IgE decreased respectively from (median) 117-89.3 kU/l (P < 0.001) during an initial period of 3 months of allergen avoidance and from 88.2 to 78.4 kU/l (P < 0.0002) during a subsequent period of allergen avoidance. No significant increase in serum specific IgE was, in contrast, observed during two periods, 22 and 9 days, of antigen exposure, changing respectively from 89.3 to 88.2 and from 78.4 to 89.1 kU/l. In contrast, nasal IgE has been significantly influenced by the alternate periods of antigen exposure-avoidance, showing a decrease from 19.75 to 4.01 kU/l (P < 0.0001) after the initial period of avoidance, followed by an increase to 9.95 kU/l (P < 0.0001) after 22 days of exposure. A significant decrease to a value of 2.37 kU/l (P < 0.0001) was also observed during the subsequent period of avoidance, followed again by an increase to 7.87 kU/l (P < 0.002) after 9 days of exposure. The evaluation of the kinetics of changes in nasal specific IgE revealed a significant decrease (P < 0.01) as soon as antigen avoidance was implemented for 3 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Christmas candy maker's asthma. IgG4-mediated pectin allergy

We evaluated a 29-year-old candy maker with no history of asthma who developed asthma after exposure to pectin, a compound manufactured from fruits and fruit rinds. Following eight years of employment during which he added pectin to a recipe for Christmas candies, the candymaker developed acute respiratory symptoms. Challenge testing with the pectin mixture caused a 40 percent decrease in FEV1. Skin prick testing was positive to the pectin extract. Total IgE was normal and pectin-specific IgE antibodies were not detected. A strongly positive pectin-specific IgG4 antibody response was present that was not detected in a control serum and could be inhibited by the addition of pectin. Antigen-specific IgG4 should be sought in IgE negative cases of occupational asthma.