Serum IL-2 inhibitor in mice. I. Increase during infection

Serum from normal mice contains an inhibitor of interleukin-2 (IL-2) which probably interacts directly with IL-2. Athymic mice and normal mice kept under specific pathogen-free conditions do not show this activity, whereas mice infected with malaria parasites have increased serum levels of inhibitor. This IL-2 inhibitor may play an important part in regulating T-cell function.