Effects of Radiation on Living Organisms Radiosensitivity of Immune Responses and Mechanisms of Project Title: Immune Reactions RX-03-O1-(b) Technical Progress in FY 1973: (Cont'd.) 16. inhibited primary tetanus antitoxin responses; after 30 days these animals gave good primary responses. Secondary antitoxin responses were largely unaltered by treatment with either CAP or TAP before the injection of booster doses of tetanus toxoid. During the past year resistance to CAP has been reported for Salmonella typhosa. The analog of CAP--TAP--has similar antimicrobial characteristics. Thus it seems desirable to explore the side effects of this chemical in more depth. Although TAP induces an immediate toxic effect to the bone marrow, it appears to be temporary and normal hematologic findings are seen again within 4-5 weeks. The study of the genetic control of antibody responses in genetically defined strains of JAX mice has continued throughout the year. The relative capacity of more than 60 strains and inbred lines of mice to produce primary and secondary tetanus antitoxin responses was evaluated. Preliminary results indicate that the various strains may be grouped into three categories: (1) early and high antibody responders, (2) intermediate, and (3) late and low responders. The HRS/J (hairless) strain produced very little antibody after primary immunization. The hairless mouse has a homozygous genotype (hr/hr); the normal mouse, with hair, may have the following genotypes (hr/+) or (+/+). The incidence of leukemia in (hr/hr) mice is 70-80 percent at 18 months, whereas the incidence of leukemia in (hr/+) mice at the same age is only 5-10 percent. It seems apparent that the mutant gerne (hr) enhances susceptibility to murine leukemia virus and the wild-type allele (+) induces resistance to leukemogenesis. (Stoner) * = ' The studies on the effect of radiation in tumor virus infection and tumorigenesis are being planned, and equipment assembled. Experiments will be initiated during the latter part of this fiscal year. (Pavlova) 17. Expected Results in FY 1974: Antibody responses in more than 80 strains of mice from The Jackson Laboratory will be determined. The various inbred strains and recombinant inbred lines will be selected on the basis of previous findings concerning the genetic control of antibody responses, The HRS/J hairless mouse strain will be used in a series of immunological experiments with BSA and HRP as test antigens, MM stological and histochemical studies need to be completed on the Locafazat ion of HRP, HRP antibody and complexed HRP in lymphoid tissues, The ant f@@@a will be tested here and the microscopic evaluation will be completed by Dr. Sordat, Cancer Institute, Lausanne, Switzerland. Enhanced antibody formation following the injection of antigen-antibody complexes formed in antigen excess will be studied in an inbred A/J mouse strain in collaboration with Dr. Habichce, State University cr New York at Stony Brook. (See Continuation Sheet) 1119213 RX- 180