THE ANTIGENICITY OF AGGREGATED AND AGGREGATE-FREE HUMAN GAMMA-GLOBULIN FOR RABBITS

Abstract

Rabbits were injected with either aggregated or aggregate-free HGG. It was found that rabbits injected with aggregated HGG produced large amounts of precipitating anti-HGG antibodies, whereas those injected with aggregate-free HGG produced no detectable antibodies, and became immunologically unresponsive to HGG.

Some rabbits were injected with ¹³¹I-labelled HGG. In these animals it was observed that aggregated HGG disappeared from the blood much faster than aggregate-free HGG. A considerable amount of the label was found in the spleen of the rabbits given aggregated HGG, but none in that of the ones given aggregate-free HGG. In the spleen the radioactivity was bound to protein. No significant protein-bound radioactivity was detected in other organs. An important amount of free ¹³¹I was found in the thyroid gland of these rabbits as early as 4 hours after the injection.

Severely hypocomplementaemic rabbits have been found sporadically. Nine such animals were included in these experiments. It was observed that their immune response to aggregated HGG was entirely normal. They also cleared the labelled protein from the blood in a normal fashion, but they retained significantly larger amounts of it in the spleen, while only small amounts of free label appeared in their thyroid glands.

The possible implications of these findings are discussed.