Species Specificity in the Immunologic Reactions and Biological Functions of Transcobalamin II 1

Summary

The reactivity between antihuman transcobalamin II (TC II) and the TC II from eight species of animals was evaluated by a radioimmunoassay for human TC II. None of the animal TC IIs reacted to the same degree as an equal amount of human TC II, although the TC II of the baboon expressed partial reactivity. The function of each TC II in promoting the uptake of Cb 1 was evaluated by exposure to cultured human HeLa cells and human lymphocytes. There was considerable variation in potency with some TC IIs having no effect, while others, such as that of the baboon, were almost as active as human TC II. The same species of TC II expressed varied potency for promoting uptake by murine fibroblasts as well. We have concluded that antibody against human TC II and the TC II mediated complete uptake of Cb1 by human cells exhibit species specificity.

The TC II-Cb1 from some species was less effective than murine TC II-Cb1 or the murine L-929 system, but some forms of TC II-Cb1 were more effective.