Persistence of immunological memory to soluble protein antigens

Abstract

The ability of rabbits to make a secondary response to certain protein antigens declines either not at all or very slowly with increase in time. The amount of precipitating antibody produced following a second injection of haemocyanin is the same whether the injection is given 2, 7 or 20 months after the primary injection. With BSA, the amount of precipitating antibody produced was the same when the second injection was given either 2 or 7 months after the primary injection, but rabbits given the second injection 20 months after the first produced 40 per cent less precipitating antibody. The level of binding anti-BSA (measured by ammonium sulphate precipitation) produced was not markedly different when the second injection was given, 2, 7 or 20 months after the first injection.

Synthesis of antibody persisted in many of the rabbits for as long as 20 months after a single intravenous injection of either haemocyanin or BSA. The antibody to haemocyanin could be detected by precipitation whereas the ammonium sulphate technique had to be used to detect the antibody to BSA.