Leukocyte histamine release in Hymenoptera-allergic patients. Correlation with skin test reactivity and changes following hyposensitization therapy

A mathematical model to quantitate histamine release from basophils challenged in vitro with insect venom

Using a two parameter mathematical model, it was possible to describe clinically obtained data from histamine release (HR) in vitro as a response to basophils challenged by insect venom. The Gompertz function used in this model not only reflects the observed HR data but can be used to predict maximal HR values from initial lower antigen concentrations HR determinations. The model was used to calculate the concentration of venom antigens releasing 25% of total intracellular histamine (HR25). This is clinically significant in that while knowledge of the HR25, or any other reference fraction, facilitates comparisons between allergic patients, it is impossible to empirically administer venom antigen concentrations that will produce exactly HR25 in a given clinical setting.

Anaphylactic reactions to Hymenoptera stings in asthmatic patients

We evaluated 587 cases with generalized reactions to stings of Hymenoptera. Eighty of these patients and twenty-eight normal controls had radioallergosorbent tests (RAST) to venoms of honey bee, yellow jacket, hornet, wasp and to phospholipase A. Those patients with systemic reactions had a significantly greater frequency of positive RAST than normal controls (51.3% vs. 7.1%, P < 0.001). The frequency of atopy (asthma/rhinitis) in case these 587 cases was only 22% and resembled the expected frequency in a general population. Asthmatic patients did not have an increased risk of developing systemic reactions to Hymenoptera stings. However, those asthmatic patients with systemic reactions to Hymenoptera stings had a significantly more severe anaphylactic reaction to a sting than non-asthmatics. These severe reactions were primarily manifested by acute dyspnoea, which appeared to represent a bronchospastic response to endogenous histamine release.

Immunologic and biochemical evaluation of the potency of whole insect body extracts

Recent studies have indicated that currently available whole body extracts have little potency and are ineffective for diagnosis and treatment of stinging insect allergy. Pure venom is a potent effective allergen but is difficult to obtain in sufficient quantities from all Hymenoptera species. In these studies, an attempt was made to prepare a potent whole body extract. Whole bee body extracts were prepared with different extraction periods and at cold and room temperatures. Potency was examined biochemically by measurements of phospholipase A (PLA) activity and immunologically by PLA and bee venom radioallergosorbent test (RAST) inhibition experiments and gel diffusion studies with the use of rabbit antisera. All extracts prepared in the laboratory had some potency, indicating that it is possible to make a whole body extract containing small quantities of PLA or bee venom. However, the potency of these extracts was minimal as compared with bee venom. Three commercial extracts were almost devoid of detectable immunologic activity. While further attempts may be made to prepare a potent whole body insect extract, these results suggest that it is necessary to obtain venom in relatively pure form for the diagnosis and treatment of stinging insect allergy.

A controlled trial of immunotherapy in insect hypersensitivity

Insect hypersensitivity is currently treated by immunization using whole-body extracts. We compared this regimen with immunotherapy using insect venoms or placebo in groups of 20 patients matched for history and sensitivity, as judged by venom skin test, histamine release and IgE antibody to venom. After six to 10 weeks of immunization, systemic reactions to stings occurred in seven of 12, seven of 11, and one of 18 patients treated with placebo, whole-body extract, and venom, respectively. Placebo and whole-body extract gave similar results and were significantly less effective than venom immunotherapy (P less than 0.01). The 14 patients with failure of treatment with whole-body extract and placebo were subsequently provided with venom immunotherapy; one reacted to a subsequent sting. We conclude that venom immunotherapy is clinically superior to therapy on whole-body extract or placebo.

Immunologic comparison of phospholipases A present in Hymenoptera insect venoms

A comparative study was made of the effect of anti-bee venom phospholipase A2 serum and anti-bald face hornet venom serum on the activity of phospholipase A2 present in yellow hornet, yellow jacket, bald face hornet, and honeybee venoms. Activity of phospholipase A2 present in the venoms was measured titrimetrically using egg yolk dispersion as the substrate. Antiserum against pure bee venom phospholipase A2 activity completely suppressed bee venom phospholipase A2 activity but failed to inhibit phospholipase A2 activity in yellow jacket, yellow hornet, and bald face hornet venoms. Anti-bald face hornet venom serum suppressed the activity of phospholipase A2 present in the four insect venoms with the inhibitory effect decreasing in the order: bald face hornet greater than yellow hornet greater than yellow jacket greater than honeybee. A combination of immunoelectrophoresis and immunodiffusion techniques gave indication of common antigenic sites in a component of yellow hornet venom and a component of bald face hornet venom. The results suggest that IgG antibodies against pure bee venom phospholipase A2 may not give any protection against the reaction(s) due to the phospholipase A2 in yellow hornet, yellow jacket, and bald face hornet venoms, while antibodies against bald face hornet venom phospholipase A2 may give some cross-protection.