Cross-reactivity among edible nuts: double immunodiffusion, crossed immunoelectrophoresis, and human specific IgE serologic surveys

Abstract

As many as one third of all food allergen anaphylactic events are related to tree nut ingestion. Although concurrent allergen sensitivity to tree nuts is common, cross-reactivity among nut antigens is less well defined. To survey serologic cross-reactivities among 7 tree nuts (walnut, pecan, hazelnut, cashew, Brazil nut, pistachio, and almond) and peanut. Human specific IgE enzyme-linked immunosorbent assay inhibition was used to identify nut allergen cross-reactivities. Single-nut rabbit antisera were used in double immunodiffusion, crossed-line immunoelectrophoresis, and crossed immunoelectrophoresis with intermediate gel studies of nut antigen cross-reactivity. Nut specific IgE enzyme-linked immunosorbent assay inhibition demonstrated no cross-reactivities between peanut and tree nuts. Among tree nuts, 2 groups with allergen cross-reactivity were defined: (1) walnut, pecan, and hazelnut and (2) hazelnut, cashew, Brazil nut, pistachio, and almond. Double immunodiffusion, crossed-line immunoelectrophoresis, and crossed immunoelectrophoresis with intermediate gel results supported the same groupings of cross-reactive tree nuts and identified several less prominent nut-nut antigen cross-reactivities between groups and with peanut. With few exceptions (notably limited peanut cross-reactivity with pistachio and walnut), peanut antigens did not serologically cross-react with tree nuts. Walnut, pecan, and hazelnut form a group of strongly cross-reactive tree nuts. Hazelnut, cashew, Brazil nut, pistachio, and almond form a group of moderately cross-reactive tree nuts. Cross-reactivities between these groups are less pronounced (notably limited cross-reactivity of walnut and pecan with Brazil nut). The strongest cross-reactivities among tree nuts follow botanical family associations: (1) walnut and pecan in the family Juglandaceae and (2) cashew and pistachio in the family Anacardiaceae.