Immune reactivities to peanut proteins, agglutinins, and oleosins.

CONTEXT

Certain individuals are sensitive enough to react to peanuts and peanut oil, sometimes with deadly effect. It is thus crucial to have an accurate testing methodology for the assessment of allergies and immune reactivities to peanuts and their components, such as agglutinins and oleosins. Currently, skin-prick testing is performed only with the water-soluble components of peanut proteins and can produce false negatives. Testing with all possible food antigens and with both immunoglobulin G (IgG) and immunoglobulin E (IgE) antibodies may offer a more accurate alternative.

OBJECTIVE

The research team intended to measure IgG and IgE antibodies against peanut proteins, agglutinins, and oleosins to identify variations in IgG and IgE immune reactivities to these antigens among the general population.

DESIGN

Sera from 288 healthy individuals-144 males of different ethnicities, aged 18-65 y with a median age of 35.5 y, and 144 females of different ethnicities, aged 18-65 y with a median age of 36.2 y-were obtained from Innovative Research, Inc. Four sera from patients with a known allergy to peanuts and 4 sera from individuals with no known allergy to peanuts were used as positive and negative controls. Several wells in the microtiter plate were coated with unrelated proteins, such as human serum albumin, rabbit serum albumin, and bovine serum albumin and used only for the determination of any background in the enzyme-linked immunosorbent assay (ELISA).

SETTING

Immunosciences Lab, Inc, Los Angeles, CA, USA.

OUTCOME MEASURES

The sera were screened for peanut-specific IgG and IgE antibodies against water-soluble proteins of peanut, peanut agglutinins, and peanut oleosins, using the ELISA. Color development was measured at 405 nM. For demonstration of the specificity of the antibodies, inhibition ELISA was performed with 4 sera that had very high levels of IgG and IgE antibodies.

RESULTS

Using mean values as the cutoff, 19%, 17%, and 22% of the specimens tested for IgG antibodies and 14%, 11%, and 14% of the specimens tested for IgE antibodies produced high levels of antibodies against peanut proteins, agglutinins, and oleosins, respectively.

CONCLUSIONS

The study's findings support the proposition that IgE sensitization to foods may not necessarily coincide with positive prick tests to commercial extracts. Falsely negative skin testing or IgG, IgA, or IgE antibody testing is often linked to the nature of the preparation of the food antigens and their use in in-vivo and in-vitro testing. The study's results support the need to improve the quality of food extracts used in the diagnosis of allergies and immune reactivity to nuts and seeds. Testing should use all possible food antigens and measure both IgG and IgE antibodies.