Human Polymeric IgA Research Articles

Improved procedure for the isolation of J-chain from human polymeric immunoglobulins

Highly purified J-chain was isolated from S-sulfonated human polymeric myeloma IgA by gel filtration and DEAE-cellulose chromatography, without using any dissociating agents. The purified J-chain was homogeneous upon immunoelectrophoresis and electrophoresis in agarose gel, alkaline-urea polyacrylamide gel, and sodium dodecyl sulfate polyacrylamide gel. The molecular weight of the J-chain, estimated by electrophoresis in sodium dodecyl sulfate polyacrylamide gel, was found to be 24 000 ± 1200 (S.D.). The J-chain dimerized in non-dissociating solvents, even in the presence of weak dissociating agents, such as 1 M propionic acid. During the isolation of the J-chain, two minor protein components which upon electrophoresis migrated, respectively, faster and slower than the J-chain itself were identified. These two components were antigenically unrelated to each other but both were clearly precipitated with anti-J-chain antisera, giving a reaction of partial identity to the J-chain. They were considered as two different fragments of J-chain, produced by some unknown protease(s).

In vitro combination of human and bovine free secretory component with IgA of various species.

The free form of the secretory component usually associated with secretory IgA can be isolated from human and bovine milk. These free secretory components of different origin combine in vitro with human polymeric myeloma IgA, with mouse myeloma IgA, and with the serum IgA of nine different mammalian species.