[Mechanisms of the effect of exogenous thyroxine on the regulation of the immune response in mice].

The influence of repeated administration of thyroxin (T4) in doses of 4 or 4000 micrograms/100 g body weight daily upon T-B co-operation and specific T-suppressor formation was studied on CBA male rats. A stimulating effect of T4 low doses on the lymph node T-cell ability was demonstrated to co-operate with the normal marrow B-cells over a process of generation of the humoral response to the sheep red blood cells within the system of singeneic transfer. The injection of various T4 doses to donors of the marrow B-lymphocytes or recipients of T- and B-cells from control animals did not alter the immune response in recipients. The inhibiting T4 effect on the formation of cell-suppressors of the antibody response to the sheep red blood cells, depending on the dose of hormone injected, was established. It is suggested that thyroid hormones are capable of regulating the immune response to thymus-dependent antigens through a selective action on regulatory T-lymphocytes.