Secondary Tetanus Antitoxin Responses in Mice Elicited Prior to Irradiation

Abstract

Secondary tetanus antitoxin responses were abolished in mice when sublethal radiation doses of 650 rads were delivered by short-term exposure 3 hr before the second injection of antigen. Nearly normal secondary responses were observed when the same radiation doses were delivered 4 days after antigenic stimulation, and sera were obtained 8 days later. Radiosensitivity of the seemingly radioresistart secondary antibody responses was demonstrated by ultimate repression of antitoxin titers when radiation was delivered 4 days after antigenic stimulation and sera were obtained 4 weeks after irradiation (32 days after the second injection of toxoid). It was possible to differentiate clearly between the capacity of these irradiated animals to produce nearly normal secondary responses and failure of the same animals to respond to a third antigenic stimulus when radiation was delivered 4 days after the second stimulus, and a third injection of antigen was given 30 min after the single exposure to 650 rads. A marked incorporation of tritium activity appeared in antitoxin produced during secondary responses of irradiated and nonirradiated mice when tritium-labeled /sub L/-histidine was injected on days 4 and 5 and on days 6 and 7 after the second stimulus of tetanus toxoid. The data indicate that themore » antibody produced during secondary responses in irradiated and nonirradiated mice was not performed during the induction phase and merely released on days 4 or 5, following the second stimulus of antigen. These findings indicate the presence of antibodyproducing cells or their precursors that have proliferated in response to the second antigenic stimulus and survived long enough after irradiation to produce nearly normal secondary tetanus antitoxin responses. (auth)« less