Total body irradiation followed by bone marrow transplantation was found to be an effective treatment for adjuvant arthritis induced in rats. This treatment is most effective when applied shortly after the clinical manifestation of arthritis--i.e., 4-7 weeks after administration of Mycobacterium tuberculosis. Transplantation of bone marrow at a later stage results in a limited recovery, in that the inflammatory reaction regresses but the newly formed excessive bone is not eliminated. Local irradiation of the affected joints had no effect on the disease. It could also be excluded that the recovery of arthritis following marrow transplantation is due to lack of available antigen. Transplantation of syngeneic bone marrow is as effective as that of allogeneic bone marrow from a rat strain that is not susceptible to induction of adjuvant arthritis. The beneficial effect of this treatment cannot be ascribed to the immunosuppressive effect of total body irradiation, since treatment with the highly immunosuppressive drug Cyclosporin A resulted in a regression of the joint swelling but relapse occurred shortly after discontinuation of the treatment.

SummaryAmphotropic recombinant retroviruses were generated carrying sequences encoding human adenosine deaminase (ADA) . Transcription of the human ADA gene was under control of a hybrid long terminal repeat in which the enhancer from the Molony murine leukemia virus was replaced by an enhancer from the 17101 host-range mutant of polyoma virus. Hemopoietic stem cells in murine bone marrow were infected with this virus under defined culture conditions. As a result, 59% ofday-12 colony forming unit spleen (CFU-S) stem cells became infected without any in vitro selection. Infected CFU-S were shown to express human ADA before transplantation and this expression sustained upon in vivo maturation. Mice transplanted with infected bone marrow exhibited human ADA expression in lymphoid, myeloid, and erythroid cell types. Moreover, human ADA expression persisted in secondary and tertiary transplanted recipients showing that human ADAexpressing cells were derived from pluripotent stem cells. These characteristics of our amphotropic viruses make them promising tools in gene therapy protocols for the treatment of severe combined immunodeficiency caused by ADA deficiency. In this respect it is also relevant that the viral vector that served as backbone for the ADA vector was previously shown to be nonleukemogenic .

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The safety and efficacy of the administration of stable iodide to protect the fetal thyroid from exposure to radioactive iodide were investigated in chimpanzees in weeks 19 to 21 of pregnancy. The mean 24-h uptake of iodide in the fetal thyroid, determined with 123I-, was 1.8%. Administration of stable potassium iodide (KI), 0.65, 1.95 or 6.5 mg per kg body weight, 1 h before tracer injection reduced the fetal uptake satisfactorily. Only the higher doses were effective after 20 h. Excess iodide may impair a child's thyroid status. However, adverse effects were not found during the 11 days the animals ingested these doses. Tracer concentrations in the amniotic fluid were 30- to 130-fold lower than in the urine. The dose to the fetus from radioactivity in the maternal bladder was estimated by computer simulation. The potential increment of the risk from this dose during the ingestion of stable iodide is smaller than the reduction of risk achieved by inhibiting the uptake of radioactive iodide by the fetal thyroid. The conclusion of the experiments is that stable iodide can be used safely and effectively to protect the fetal thyroid against contamination with radioactive iodine.