Polymeric Plasma IgA Recovered from Cohn Fraction III Precipitate Binds Recombinant Human Secretory Component

Cohn fraction III precipitate (CFxIII-ppt) is a discarded byproduct of the recovery of IgG from pooled donor plasma using cold ethanol fractionation. Tons are discarded annually. We propose that recovered IgA has the potential to be a new orally administered immunoglobulin therapy. Water content of CFxIII-ppt was determined by weighing wet and then dried material. IgA was recovered from rehydrated CFxIII-ppt by jacalin affinity chromatography. Concentration of IgA was measured using a spectrophotometer. Proportions of monomer, dimer and polymer in IgA were determined by analyzing size exclusion chromatograms. ELISA demonstrated the association of J chain with IgA dimer and polymer. Immunoblotting showed dimer and polymer binding to recombinant human secretory component (rhSC). Antigenic specificity was determined by ELISA. CFxIII-ppt is ∼65% water. Up to ∼15 mg of IgA is obtained per g of CFxIII-ppt. Recovered plasma IgA is 50.2 (+/-5.36 SD]% monomer, 49.8 (+/-5.3SD)% dimer and higher polymers (n=7). The IgA dimer and higher polymer fractions contain J chain and readily combine with rhSC to form dimeric and polymeric semisynthetic secretory IgA. We previously reported that IgA recovered from CFxIII-ppt binds to Clostridium difficile toxins A and B as well as peanut extract. We now extend the known antigenic specificity of recovered IgA to include Campylobacter Plasma IgA from CFxIII-ppt is slightly less than 50% polymeric IgA (dimer plus larger polymers). Higher IgA polymer as well as dimer can be converted into secretory IgA. Pooled plasma contains IgA with reactivity to Campylobactor.