Plasma Derived IgA from Healthy Donors Binds to Peanut Extract and Inhibits Peanut-Induced Rat Basophil Activation
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Michael R. Simon, MD FAAAAI, George N. Konstantinou, MD PhD MSc
Rationale: IgA and IgE are both mucosal immunoglobulins.  We hypothesize that food specific IgA is capable of interfering with IgE mediated allergy effector cell activation.  Oral administration of food specific secretory IgA prepared from plasma IgA may ameliorate food allergy symptoms.

Methods: IgA from more than 3000 healthy plasma donors was purified from a by-product of intravenous immunoglobulin manufacture.  The ability of this pooled IgA to bind to crude peanut antigen was determined using an ELISA.  Specificity of binding was confirmed using an ELISA inhibition assay.  Monomeric and dimeric IgA were separated by size exclusion chromatography.  Binding of IgA monomers and IgA dimers to peanut were each determined independently using an ELISA.  Leuciferase transfected rat basophil leukemia cells were sensitized with peanut specific IgE using serum from a peanut allergic subject.  Inhibition of peanut-induced rat basophil leukemia activation by plasma derived IgA was determined using luciferase-produced light emission.  

Results: Pooled plasma IgA from healthy plasma donors binds to crude peanut extract.  The binding is inhibited in a concentration dependent manner by soluble peanut antigen.  Both IgA monomers and IgA dimers bind to peanut extract.  Peanut extract pre-incubated with plasma derived IgA partially inhibits the ability of peanut to activate IgE sensitized rat basophil leukemia cells in culture.  

Conclusions: Both IgA monomers and IgA dimers derived from pooled healthy donor plasma bind to crude peanut extract.  Plasma derived anti-peanut IgA partially inhibits peanut-induced rat basophil leukemia cell activation demonstrating that it is physiologically active.