Immuno-cross-reactivity between alpha-macroglobulins from pig, dog, rat and man including human pregnancy-associated alpha 2-glycoprotein.

The antigenic relationships between the alpha-macroglobulins in human blood plasma and in serum from pig, dog and rat were investigated using ordinary immunoelectrophoresis and line immunoelectrophoresis. The results imply that these alpha-macroglobulins are more or less antigenically related. This is true also for human pregnancy-associated alpha 2-glycoprotein which is the only alpha-macroglobulin without reported proteinase-inhibiting properties. Among the alpha-macroglobulins a reciprocal cross-reactivity was observed for eight pairs, indicating a close structural relationship.