Antigenic competition: cellular or humoral.

The injection of one antigen into mice inhibited the response to a second when 1 to 10 days separated the two injections. When the same type of inhibition was attempted in gamma-irradiated mice reconstituted with normal spleen cells, the inhibition was greater in mice receiving 50 million spleen cells than in those receiving 10 million. The results are interpreted as favoring a humoral mechanism of inhibition.