Influence of antigenic stimulation on lymphoid cell traffic in the chicken. I. Increased homing of thymus-derived cells to the bone marrow after antigenic stimulation.

Six-week-old chickens were either immunized with a single intravenous injection of human serum albumin (HSA) or injected intravenously with physiological saline. 24 h after the HSA or saline administration the chickens were locally labelled in the thymus with 3H-thymidine in vivo. 48 h after the intrathymic labelling the chickens were sacrificed and the influence of the antigenic stimulation on the distribution of label between different lymphoid organs was studied with a radiochemical method based on measurements of tritiated DNA, and with autoradiography. A significantly increased proportion of thymus-derived label was demonstrated with the radiochemical method in the bone marrow of the immunized chickens, as compared to the saline-injected controls. With autoradiography, an increased number of heavily labelled thymus-derived cells were found in the bone marrow of the HSA-immunized chickens. The majority of these cells were small to medium-sized lymphoid cells, but a number of them were large lymphoid cells. None of these cells were plasma cells. There was no apparent increase of thymus-derived label or heavily labelled thymus-derived cells in the spleen or in the cecal tonsils of the immunized chickens. Heavily labelled thymus-derived cells could not be demonstrated in the bursa of Fabricius.